Transmission Fluid Change vs Flush

When a vehicle owner drives into any car maintenance facility, they may or may not know what services they really need to keep their car running smooth and efficiently.  It’s easy to be taken advantage of.  They may need the technician to explain a little bit more about the ins and outs of maintaining their vehicle. Particularly, when they are not familiar with the differences between a transmission flush vs a transmission (fluid) change.


The transmission is just not a part of the vehicle which is serviced often, and as such people often don’t have a very good idea of what service it needs.  It’s a great idea to know as much about a transmission flush vs change as possible before you roll into the shop.


Knowledge is power.  You don’t want to get a flush if it is not something that the manufacturer calls for in the routine maintenance schedule.  That is unless the transmission has been under heavy stress, such as towing, hauling, or racing.  With that said, here is a brief overview of each.


 Transmission Fluid Change vs Fluid Flush

transmission flush vs change

Although these services use different names, a fluid flush and a fluid change are 2 completely different services. Particularly, because when the vehicle owner asks for a transmission fluid change, the maintenance technician will concentrate their efforts on draining out all of the dirty fluid from the transmission, while a transmission flush is meant to get rid of all the fluid inside of the pan, the torque converter and its cooler lines. So, there is a significant difference in which one the vehicle owner chooses.


Above, we listed the physical differences.  But, just as important, there are heavy cost differences.  A transmission flush is significantly more expensive than a fluid change.  Is it even necessary to pay the extra money for the flush?  They need to give you good reason that justifies the flush, such as:


  • Metal shavings in the pan.  This may mean that your transmission is doomed anyway, but shavings will finish it off quick.
  • The factory maintenance schedule calls for it.  It is not often that they do call for a flush anymore, but as vehicles creep into extremely high mileage situations, the manufacturer may call for it.
  • There’s burnt transmission fluid.  If the technician can show you that your transmission fluid is burnt, a flush may be warranted.  You should still check the fluid yourself for a burnt condition.  Pull the dipstick and make sure that the fluid is actually a dark color.  Make sure to deposit that transmission fluid onto a white paper towel or piece of paper.  If you are shown your clean fluid on a shop towel, it is certainly going to look darker than it really is.  Here is a fantastic guide that covers what does the color of your transmission fluid mean.
  • Your car has been used in a heavy-duty fashion.   Heavy duty If your car has been used for something like driving for über causes the same wear and tear on the vehicle that a taxi does.  Therefore, the transmission should be treated just like a taxi’s.  This means a frequent maintenance schedule that involves flushes when they normally wouldn’t be done.


Here are some reasons not to get a flush:

  • Your manufacturer may not want you to.  The company that made your vehicle is definitely going to want what’s best for your vehicle.  Vehicle longevity is big selling point.  One manufacturer that has a stellar reliability record is Honda.  They typically recommend that you drain out a portion of the fluid and replace that amount to not shock the system.  As your fluid circulates around the clutches and servos it gets (for lack of a better term) seasoned.  This seasoned oil can really develop a life of its own.  By replacing a small portion of it, you are insuring that there will be no shock.
  • It’s typically very costly, much more so than just getting the change done.  If there is no reason to get one done that you can justify to yourself, just get it changed.


Transmission Fluid Change


When the maintenance technician does a fluid change, their responsibility is to make sure the pan is completely drained and the transmission filter is replaced. In this process, all of the fluid will not be removed.   Especially because a huge chunk of this fluid will be left inside the torque converter as well as the cooler lines. It is also important to note that there are both pros and cons to this service and they are listed as follows:



  • It is significantly more affordable than getting it flushed.  Since most of us have to watch where are money is going, the change (or partial change) is the cost-effective option.
  • Vehicle owners can teach themselves to do the transmission fluid change themselves.  It’s not that difficult to do, especially if the transmission involved has a fluid drain plug.  Not all of them do.  If changing your own oil is a 3 out of 10 in the difficulty arena, than changing the transmission fluid is about a solid 5.  Still doable.  If you are going to give it a shot, practice a few times by getting comfortable with changing the oil yourself.



  • You won’t get all of the old fluid out.  If there has been an issue that leads you to believe that you may have harmed the transmission, such as low transmission fluid or drag racing, a flush may be more appropriate for your vehicle.




Some people may say that the transmission flush is superior to the fluid change. Specifically, because none of the old fluid is left behind. Therefore, any contaminates that could adversely affect the transmission are no longer a threat to its proper functioning.

All things being equal, many vehicle owners would prefer a flush and not a change. With a flush, all of the fluids are removed from the pan, cooler line and the torque converter. As a result, the new transmission fluid is not mixed with any of the old dirty fluids. Meaning the transmission will perform at its peak efficiency.

Before a vehicle owner takes their car in for transmission servicing, it is essential that they understand the differences between a transmission fluid change and a transmission fluid flush. Since both of which have pros and cons, people should make sure that they understand an overview of each so that they can make an informed decision.

Posted in Transmission repair cost, Uncategorized

4l60e rebuild cost

Before digging right into 4L60E rebuild cost, it’s important to weigh whether or not a rebuild is even the right thing to do.  There is certainly a threshold of spend where it begins to make more sense to go with a “new” transmission.  We will answer your question immediately below, and we’ll go over other options after that.


Cost of rebuilding the 4L60E Yourself

The cost of rebuilding the 4L60E yourself is only a couple hundred bucks.  You can find kits on Amazon or eBay that you can for well under $300.  Here’s one such kit from Amazon.  If you are going to rebuild your 4L60E yourself, you are going to want the rebuild kit to be for the proper year and car.  Different cars may use different depth pans, especially when comparing Corvette to other GM models.

Rebuilding an automatic transmission is much more difficult than rebuilding an engine.  It’s certainly more difficult than rebuilding a manual transmission.

Here is a video of a complete 4L60E rebuild.  If you’ve never done it, you’ll want to watch the whole thing.

Cost of Having a shop Rebuild the 4L60E

If you plan on having the shop rebuild it, and you pull and bring the transmission to them, it’s possible to have it done for $1000 or under.  Not much under, though.

If you have a shop pull, rebuild, and reinstall the transmission it can cost anywhere from $2000-$4000.


Rebuilt and Remanufactured 4L60E

Maybe the shop tells you that the transmission is shot, or you just want to drop a new one in instead of rebuilding the old one.  Remanufactured 4L60E’s will be more expensive than having it rebuilt.  Both are fine options when considering a 4L60E replacement.

This is due to the location of where the work is done.  A remanufactured transmission is typically rebuilt by the original manufacturer to ensure exact OEM specs.  Whereas the rebuilt unit may be rebuilt on site by the transmission shop that may use parts that are better or worse than the originals.

Don’t let the thought of going with a rebuilt unit scare you though.  As long as a shop is reputable, they’ll go through and replace all of the components that wear.  If you aren’t sure about the transmission shop in your area though, a remanufactured unit is a safe bet.


Used 4L60E

The 4L60E is one of the most popular transmissions made in the last century.  They are everywhere in salvage yards.  Finding one used can be the most economical options, especially if you are going to do all of the work yourself.  I like to look for a low mileage vehicle, that has been rear ended.  Even better, if you can find a Tahoe or Suburban.  It’s a pretty safe bet with them that they aren’t going to have done a lot of towing.

You should be looking for a 4L60E that is roughly the same year as yours.  As a general rule, you can’t swap a 4L60E made to operate with a V8 with one that was behind a V6, so be careful.  Even if the engine is missing, you can use the tag inside of the glove compartment to identify the transmission code.

You’ll also need the engine code to make sure it was a V8 car or truck.  The code are all alphanumeric with 3 digits.  For instance:


LS1, LR4, LM7, LQ4, LS2, etc….


These are all engine codes for GM LS V8’s

MD30 is often stamped on the case of the 4L60E.  The early ones look identical to the 700r4, which is stamped MD8.

There’s a whole article on this site dedicated to 4L60E identification, it also has a link to a great video that explains it all in detail.



Good luck whatever you decide to do.  If you do it yourself make sure you have parts for your particular transmission.

Posted in Uncategorized

LS1 Transmission

The LS1 engine first made its debut in the 1997 Chevrolet Corvette.  One year later, it made its way to the  Camaro Firebird twins.   All automatic transmissions that the LS1 came with are computer controlled.

The LS1 engines really used two different transmissions.  Those were:


  • T56– This transmission is the manual option on all of these cars.  It has six forward gears.  The fourth gear is a direct drive.  The fifth and sixth gears are both overdrive gears.  With this transmission the LS1 was quite capable of upper 20’s in mpg.  The T56 is nearly bulletproof and finding one with 100k should not be cause for concern.  The non Vette versions go for almost 2k on eBay.
  • 4L60E– The automatic version of the transmission that came with the LS1 is the 4L60E.   Some cars were equipped with the 4L65E.  For all intents and purposes.  This is the same transmission.  They look identical on the outside.  The 4L60E has four forward gears.  The third gear is the direct 1:1 drive.  Fourth gear is a .70:1 overdrive.  This transmission is quite reliable.  Shifts are controlled by the computer using telemetry from the engine.  That’s where the “e” comes from in 4L60E.


LS1 Transmission for the Corvette

LS1 Transmission

The Corvette transmissions are different than any of the other LS series transmissions.  That’s because the Vette went with transaxles for the C5 generation in order to get closer to the desired 50/50 weight ratio of a true sports car.  This means that the transmission is behind the driver, instead of in front of them.  It uses a torque tube to get the power to the transmission.


Since the engineers at General Motors used modified versions of the LS1 transmission for the Corvette.  They are not compatible with any other LS1 transmission.  You will often see these transmissions going for peanuts on EBay.  They are not compatible at all.  In fact, if you see a T56 going for less than $1,000, this should be a red flag.  They never have a traditional bellhousing noted to them.


  • T56– The Corvette used a custom spec T56 to fit in its transaxle.  The design only makes one suitable for transplant into another Corvette.
  • 4L60E– Just like the T56, it is only going to work for the Corvette.


The good news is that if you are looking to pick one of these transmissions up for the Corvette, they are considerably cheaper in used condition than the traditional transmission bolted straight to the engine version.


LS1 Camaro Transmission

Unlike the Corvette, which changed from the C4 generation when it got the LS1, the Camaro was in the middle of the 4’th generation.  While the Camaro and Firebird.


  • T56– This version of the T56 is the most desirable for people swapping one into an older car.  This is due to the excellent shifter location.  It’s right on top of the transmission.  The other ones use linkages to reach the shifter.  A low mileage version of this transmission is going to be the most expensive of all T56s in the used arena.  It is extra important to make sure that when you are looking at a potential T56 replacement for an LS1 Camaro or Firebird, that you don’t inadvertently end up purchasing one of the T56 transmissions that came with the LT1 engine.  They use a pull instead of push throw-out bearing.  They also need a different input shaft.  The geometry is all off.  With the right bellhousing and input shaft they will technically work though.  Here’s a good writeup of differences between LT1 and LS1 T56’s.
  • 4L60E– Same story as the T56.  The transmissions will not bolt to one another’s engines.  Unlike the T56, the 4L60E was also put behind the six-cylinder version of these cars.  These 4L60E’s will not bolt to the LS1.  Make sure that you know how to identify which is which.



GTO LS1 Transmission

The only other major muscle car that came with the LS1 was the Pontiac GTO.  These cars are based off of an Australian design, and had a very limited run in the United States.  There really isn’t much about them that you need to look out for.  They never had the old small block Chevy, so compatibility isn’t really an issue.   They also use the standard engine and transmission layout, so there’s nothing there either.


The only thing to really keep in mind is that if you are looking for a replacement T56, the shifter is in a different place, so they won’t easily swap out with the LS1 Camaro.


Other transmissions with the LS1

It is quite possible to use many other transmissions with the LS1.  There is a whole article on it here called LS swap transmission guide, so head on over there if you really need to research.  Here are some of the broad strokes though.


  • You can bolt almost any transmission up to the LS1, even the classic GM transmissions. All the way from the  Powerglide to the TH400.  This is thanks to GMs retaining of the same basic bolt pattern for the bellhousing.  There will be an unused bolt hole in some applications, but this does not compromise structural integrity.
  • The older gm automatic transmissions also need a spacer to get the flexplate and torque converter to hit at the right location.
  • Any transmission swap is going to require a re-flashing of the computer. The transmission shift codes will have to be removed so that the LS1 engine runs without considering the transmission.


Feel free to leave a comment if there is anything you’d like to add!

Posted in 4L60E, LS Swap, T56

How to Check Transmission Fluid

Automatic transmissions are complex and confusing.  But, checking the transmission fluid certainly isn’t.  We’ll cover the two most vehicle types and where to look for the dipstick.

Before you Begin

Most manufacturers recommend that you check the transmission fluid with the engine at operating temperature.  So make sure that you’ve done that.  If you’re not sure that your vehicle needs to be at operating temperature, go ahead and pull out that owners manual and check (or google it, that’s how you got here).  You’re also going to need a rag to wipe the fluid onto.

Also, a quick work of caution.  Whether the engine is on or not, an electric radiator fan can kick on and take a finger off.  I like to treat them like I would a weapon and assume it is always loaded (or ready to kick on).  You’ll also be near hot exhaust so make sure you know what the exhaust manifold is and make sure that you don’t go and get yourself burnt.


Tools Required

The only tools that you really need are towels and a funnel.  Both of these you can find around the house or apartment.  If you are looking at a tight engine compartment where you’ll have to be pouring from a distance, this funnel will work great for that. It’s like eight bucks on Amazon.


Locate the Dipstick

Safety is job one.  Job two is to find that dipstick.

Here are the different scenarios you may come across:

  • Front Wheel Drive-  It’ll more than likely be on the drivers side low and attached to the transmission.   Here is an example of what a typical front wheel drive dipstick looks like
  • Rear Wheel Drive-  The dipstick is usually located near the passenger side firewall on a rear wheel drive vehicle.

Check the Fluid Level

The next thing that you are going to need to do is check the level of the transmission fluid.  The first thing you’ll want to do is pull the dipstick out.  As the transmission spins it slings fluid up the dipstick.  This means that you need to wipe off this fluid and put the dipstick all the way back in.  Once you do this you will have a nice clean and crisp reading.  Now if the fluid level is fine skip down a couple sections to the checking of the color section.  Otherwise, directly below we’ll go over what to do if the level is too high or low.

What if the Fluid Level is Low?

If you are reading an article on this it’s probably not a stretch to assume that you may not know what to do about filling the transmission back up.  That’s ok.  Most people get tripped up because they don’t realize that the little dipstick tube is the point of entry for new fluid.  It seems a bit more obvious on front wheel drive cars than rear.  If you are checking your fluid because you have reason to believe that it may be really low, here are some common symptoms of low transmission fluid.

The next obvious step is to add fluid to the car, right.  Well how do you go about doing that?  You’ll need a funnel with a really narrow neck.  If you don’t have one you can ask for a paper funnel from the gas station next time you fill up.  Most good gas stations have one.  If the dipstick was ready

What if the Fluid Level is High?

The first thing you need to do is check it again.  While it’s not entirely impossible that the fluid is overfilled, it’s rare.  Now if it is overfilled it is very important to remove the fluid and syphon it to the correct level.  Here’s a good syphon on Amazon.

Check the Fluid Color

Fluid color?  Even if you don’t think that you are having transmission problems, you should still check the fluid color.  Transmission fluid coloration tells you so much about what is going on with the transmission.  It only takes a moment or two.  It does help if you dribble some fluid onto a piece of paper, or a paper towel.  The white color will let you see the true color of the fluid.  Here’s more on transmission fluid color.


Posted in DIY

Useful Links

Posted in Uncategorized

2003 Chevy Trailblazer Transmission

The 2003 Chevy Trailblazer was built on the same platform as the Colorado and GMC Canyon twins.  They were both rear wheel drive and used the same drivetrain components (for the most part).  Trailblazers used the 4L60e across the board regardless of which engine was in front of it.  But, these particular versions of the 4L60E use a different bell housing than the LS engines.  This means you need to be really careful when you’re looking for a replacement transmission, because they’re not easily swapped for one another.

The later 4L60E transmissions use a two piece bell housing, which means that you can swap the bell housings out.  The Trailblazer came from the factory with Dex III transmission fluid.  General Motors suggests that you replace it with Dex VI.  The “drain and refill” transmission fluid capacity is 5.0L.

2003 Trailblazer Transmission


Common Trailblazer Transmission Problems

By 2003 the 4L60e had a decade of refinement to it, which made the transmission one of the most reliable things on the vehicle.  In fact, there were so many issues with the L6 engines that were put in these vehicles that the engine would almost always give out before the transmission.  I don’t really have any statistics to back that one up, but I have seen plenty of real life examples of that exact scenario.  If you’re one of the few people lucky enough to have a v8 version of the Trailblazer you’re

If you’re reading this at the time it was written, the 2003 Chevy trailblazer is 15 years old. That means that there has been a lot of time for parts to degrade.  Fifteen years is a lot of time for a wiring to go bad, harnesses to come loose, or not have any maintenance done.

Here’s more on 4l60e problems.

Bad Fluid

When you’re looking for a transmission problem in an older vehicle a good place to start is to take a look at the transmission fluid.  Does it smell burnt? What color is it?  It can tell you a lot about the condition of the transmission.

If your Trailblazer has it’s original transmission it may have never been changed at all.  Transmission fluid is one of the most neglected pieces of automotive maintenance.


Limp Mode

When it comes to entering limp mode, these transmissions are notoriously fickle. The transmission enters limp mode because their is some sort of electronic sensor that is giving it a signal that is out of it’s normal operating range, usually one of the shift solenoids.

Here’s much more on limp mode.


Swap Compatibility

If you choose to replace the transmission yourself you need to be really sure that you are getting another 4L60E that is compatible with the one that you are pulling from your Trailblazer.  Certainly a 4L60E from the 90’s is not going to match up.

You’ll need to find a transmission from an L6 GMC Envoy or Trailblazer, if that is the engine you have.  If you have a V8, your options are wide open.  Just make sure that you are checking that they are compatible.  Here are a few good resources for that:


How much should a rebuild cost?

The 4L60e has been around for very long time, and is one of the most mass-produce transmissions ever made. That’s good news for you, because that means that there’s plenty of replacement parts available, and they’re relatively cheap.

Also, another thing that you have going for you is that The 03′ Trailblazer is rear wheel drive, which means that pulling the transmission is relatively easy to do.  This will keep your labor cost down quite a bit compared to working on a front wheel drive vehicle.

If you are looking to take an 03′ Trailblazer in to have the transmission rebuilt and replaced, $2000 is a pretty good price.



While the 4L60E that comes in the Chevy Trailblazer ( and GMC Envoy) is incredibly durable, they can go bad.  If they do go bad it’s important to replace it with a similar transmission.  There are many compatibility issues.  If you do your due diligence, you will have your 03′ Trailblazer back on the road in no time.

Posted in 4L60E

What Color is Transmission Fluid

What’s in a color?  The answer is a ton of information when it comes to transmission fluid color.  It is one of the best ways to tell the overall health of your transmission.

What does healthy transmission fluid look like?  The short answer is a nice amber color.  And, that is assuming that you even have a manufacturer that starts with amber transmission fluid. There are some vehicles that use other colors, but for the most part they all use a transmission fluid that starts with some sort of bright red clear color.

Transmission Color Chart

All bets are off once the transmission fluid leaves the bottle.  As soon as it enters the case it gets to work doing many jobs that are required of it.  The fluid will begin to darken in color right away. This changing of the color doesn’t necessarily mean that there’s anything wrong.

There is simply an amazing amount that you can learn about a vehicle by looking at the transmission fluid.  Just like motor oil, automatic transmission fluid gets darker with age.  This is itself does not necessarily indicate a problem.    Heat can cause ATF to darken over time.


Light Amber or Red Colored Fluid

Red Transmission Fluid Graphic

The red color that you see in transmission fluid is from a dye added to it.  Without it there would be almost no color to the fluid at all!  Don’t be deceived if your fluid looks great.  The color of the fluid is not an indication of transmission wear, or the last time that it was serviced.



Maroon Transmission Fluid

If yo check your transmission fluid and it appears as a nice maroon color, that is an indication of fluid that has been in the case for quite a few miles.  Heat causes the dye in the fluid to change color and get darker.  Fluid that is this color is usually just fine.  In fact, some ATF even comes that dark straight out of the bottle.



Brown Transmission Fluid Color

If you are having difficulty distinguishing from the color of your transmission fluid and motor oil, than you officially have dirty transmission fluid.  Dirty does not mean dangerous though, and is not cause for alarm by itself.  If the only  thing that appears to be wrong is that the transmission itself is in need of a proper a servicing.

You’ll see the situation a lot where someone is looking to but a car and they are really put off by the dirty fluid.  It is not an indication that anything is wrong with the car.  But, brown fluid should serve as a warning that the maintenance schedule has not been followed.

Extremely Light Pink Fluid

Pink Transmission Fluid Color

This color is an indication that antifreeze or water has corrupted the transmission.  Of all of the colors mentioned, this is the one that would give me the most concern.  Water is almost impossible to get out of the transmission.  It usually gets in there through a failing radiator.  It can also get in there if you drive through floodwater.

If you have fluid that is this color get your transmission looked at as soon as you possibly can.  Water is actively destroying your transmission.  Anti-Freeze is especially corrosive.

Water contaminated transmission fluid can also have a foamy look to it.  This will occur when the radiator or damaged line is allowing bother air and water in.


Black Transmission Fluid

Black Transmission Fluid Color

While amber, brown, and black are  usually harmless, that is not the case with black transmission fluid.  The reason that the fluid has gotten to be black is because of issues in the transmission.

To the untrained eye, brown and black transmission fluid have similar colors.  If you are unsure give it a sniff.  Black transmission fluid smells.  It smells bad because something has burned in order to get that smell.  It is usually caused by worn and slipping clutches, torque converter problems, or other transmission failure.  It is an indication of a serious problem and the transmission is going to require servicing.

Silver Tint or Silver Shavings

If you run into any of the colors above and find silver shavings in it, you have a major problem with the transmission.  I know most mechanically inclined people are thinking “well of course there’s a problem”, but you never know who is going to be looking to a page like this for help.

This indicates metal on metal friction.  Parts are actively grinding against each other.  Failure is imminent.  Get your transmission serviced as soon as possible.


What happens is you overfill the transmission fluid?

The transmission fluid may foam and ironically become starved for lubricant.  More on that here:


What does Automatic Transmission Fluid do?

ATF moves the heat generated by the engine to the radiator. It lubricates the transmission, and it moves the power through the torque converter. That’s a lot for one fluid to do.

Transmission fluid is a type of hydraulic oil.  It is highly flammable.  A motor uses oil for lubrication, water for cooling, and a crank and pistons to transfer energy to the rest of the vehicle.  Transmission fluid combines all three of these jobs into one fluid.  It needs changing way less often and is often one of the most neglected parts of the vehicle.


Looking at the coloration of the transmission fluid is a great way to determine what is going on inside your transmission..  Remember, a color other than red or amber does not necessarily indicate a problem.  Regardless of the color of the fluid, if the it gives off an odor and smells burnt, get the transmission looked at.



Posted in tech

Limp Mode Causes and Solutions

Any automatic transmission made within the last 15 or 20 years is going to be a computer controlled.  And, just like a modern engine, the computer now knows when there’s something wrong with the transmission.  If the computer thinks that there’s some sort of critical problem is going to destroy the transmission, it will put the transmission in something called limp mode.  Limp mode can also be referred to as fail safe mode.

What is Limp Mode?

Limp mode is a condition where the computer will make the transmission operate in a manner that will save it from its own destruction.  Limp mode’s job is to minimize the potential harm from a major mechanical failure.  As the name itself implies, it is designed to get you and your vehicle safely in for a repair without leaving you stranded on the side of the road.

What Causes a Vehicle to go into Limp Mode

The computer generally does this by reducing the number of gears the transmission can use.  Although which gears are eliminated generally changes depending on which transmission make and model it is.   It’s generally a rule that the overdrive gear will always be deactivated by this limp mode condition.  Typically, the torque converter will stop locking as well under limp mode conditions.

An automatic transmission has a range of signals readings from the sensors that the computer sees as normal.  When one of these sensors sends a signal outside of the normal operating parameters limp mode is triggered.  The transmission will often shift rougher, and the torque converter lock will stop engaging.  Most people realize this happened when they get on the highway and their vehicle screams down it at a high RPM.  Besides the limited and firm shifts coming from the transmission, many vehicles have a noticeable lack of power coming from the engine as the computer does everything that it can to save the transmission.

Common Causes

There are several different conditions that can cause limp mode. The common theme of the issues listed below are a faulty reading from a sensor that is critical to the operation of the vehicle.  Once you understand that, than the only question left to ask is it a false reading or is there something really wrong?

  • Computer Problems–  A problem with the vehicles ECM can cause limp mode, although this is definitely not where you should start looking, but
  • Damaged Electrical Connection–  Over the life of a vehicle the wiring harness that connects the transmission to the ECM can become damaged.  This can alter the signal that the computer receives, triggering limp mode.  This is much more likely than a computer problem.
  • Loose Connection–  Older vehicles have had over twenty years to get a loose connection on one of it’s wiring harness plugs.  All wiring harnesses utilize plastic keepers to secure them to the sensors.  Plastic melts and breaks just like everything else.  Has your vehicle been in the shop in the last few months?  Maybe the mechanic damaged a connection or didn’t quite get a harness snapped in all of the way.  You would be shocked just how much this can and does occur.
  • Water Damage–  The thing about modern vehicles is that they are virtually bulletproof compared to the old non computer controlled predecessors.  But, their Achilles heal is the complex wiring that they use to operate.  It can be confusing to deal with.  If you’ve gotten the harness wet or suspect your vehicle has been in a flood, this very well could be causing your limp mode situation.
  • Faulty Sensor–  Your vehicle relies on many sensors.  These include the MAP sensor, throttle position, crank position, and vehicle speed.

What Limp Mode Does to Protect Your Vehicle

If your vehicles ECM receives signal that there may be a potentially catastrophic issue, it’ll trigger the limp mode and trigger your check engine light.  It than switches all of the vehicles timing and shift tables over to a less aggressive (and therefore less damaging) performance table.  Think about it like starting your computer in safe mode.

Limp Mode Causes and Solutions

In a transmission the computer will increase the pressure in the lines in order to protect the clutches.  This makes shifts way more rough (if your vehicles limp mode gives you more than one gear)  Although it seems counterintuitive, a hard shifting transmission is better on the clutches and bands because it allows for less slipping.


All vehicles built after 1996 have OBD2 built into them.  Head to your nearest AutoZone and have it tested.  Make sure that you head the limp mode warning and actually take the vehicle in for repair and don’t drive it like that for long.  There is a good chance that you could be causing more damage to the vehicle every second that you continue to drive it.  Hopefully you won’t end up finding out that you are looking at a major repair.  Good luck!

Posted in tech

Signs of Torque Converter Problems

The torque converter is responsible for converting the energy generated by the engine at the flywheel and transferring it to an automatic transmission.  It functions in the same place in the driveline as a clutch would, creating a bridge between the engine and the transmission.  When they go bad, they have the potential to leave you stranded.   Understanding them certainly can keep you from being stranded on the side of the road.   So let’s go over common torque converter problems.

The biggest difference between a torque converter and a clutch is how they transfer the energy between the flywheel (what a clutch connects to) or the flex plate (what a automatic transmission connects to).  The clutch will slip using physical friction between the clutch disk and flywheel.  The torque converters hydraulic connection builds pressure as rpm increases.  This is worth noting because it’s important to understand how something works to properly diagnose and fix it.  Here is more on exactly how a torque converter works if you are so inclined:

Causes of Torque Converter Problems

There are many different things that can cause torque converter problems.

  • Low or Dirty fluid–  Transmission fluid is the lifeblood of the transmission and the torque converter bolted to it.  If there isn’t enough it can’t do its job.  This  will in turn cause the transmission to overheat.  This is one of the most common causes of torque converter problems.  If the transmission fluid is dirty and old it won’t be able to do its job as a hydraulic fluid as well.  This can lead to a feeling of extra slipping and chattering at speed.  Make sure you take a look at the fluid before you do anything with your transmission.  If you don’t know or can’t remember the last time it was changed or serviced this would be the place to start.
  • Worn Clutches–  The clutch that locks the transmission to the engine at highway speed can wear out just like a normal manual transmission clutch.
  • Bad Seals–  This is one of the most common issues that causes a torque converter to go bad.  It’s usually pretty detectable, as there will be a pool of fluid beneath the bellhousing.
  • Loose Torque Converter Bolts–  This will create the same symptoms as the bad seals in that the converter is going to puke a bunch of ATF all over your garage floor, but you should also be feeling quite the vibration at speed.  If you suspect this could be what is going on with your transmission, just know that if those bolts come all the way out the least that is going to happen is that it disengages from the input shaft.  Most likely it’s going to really do some real damage to the crank and input shaft.

Faulty Torque Converter Diagnosis

Above we laid out the issues that cause a torque converter to go bad. Here we are going to discuss what it actually feels like in your vehicle.  Before diagnosing any transmission issue, you’ll want to drive to let the engine warm up to its normal operating temperature.  This will ensure that the transmission is shifting as it would nearly all the time that it normally operates.

After you’ve let the transmission warm up turn the radio off and roll the windows up.  You’re going to want to pay maximum attention to what’s going on with both the engine and transmission.  Pay particular attention to any shuddering and vibration as you accelerate.  Shuddering and vibration are in no way a guarantee that something is wrong with the torque converter.  I’ve outlined a few examples of other things that could be wrong if there is a vibration below.

A common issue that happens with front wheel drive cars is that the axle shafts (or cv shafts) go bad.  This can create a similar vibration, but it will get worse or only exist when you go around corners.  Below are signs that will tell you if the torque converter is damaged or going out:

  • Slipping Transmission at low speed-  The torque converter “stall speed” is the speed that the engine needs to be turning before the torque converter will begin engaging the transmission.  When a torque converter is malfunctioning it can cause this stall speed to change and feel like the transmission is slipping.  If you suspect this is happening with your car, has your fuel mileage changed?  This iso fen a sign that the transmission isn’t operating efficiently.
  • Slipping at highway speed–  Nearly all modern automatic transmissions have what is called a locking converter.  This type of  torque converter has been the standard since the mid eighties, and is universally used today.  What it does is have  clutches in it that let the transmission make a physical connection with the engine.  This eliminates all operating inefficiency when it is at high speed (usually after about 45 miles an hour).  This increases the fuel mileage achieved and brings an automatic transmissions efficiency more in line with a standard transmission.
  • Chattering or vibration–  If you feel a vibration going down the road it could very well be the torque converter.  The fluid level may not be where it needs to be.  Have you ever had an uneven load in the washer?  It spins around and the washer sounds like it is beating itself to death.  The torque converter is the same way when it can’t spin the right amount of fluid through itself.  It is way less likely, but the bolts that hold the torque converter to the flex plate can come loose and cause a vibration at speed.

Repair the Converter ASAP

A torque converter has the potential to keep on going for months after it first starts to go out.  But, when it does, it’ll blow out and toast the transmission.  It’ll rain debris and metal destroying it almost instantly.  Don’t put it off.  If you aren’t sure, take it to a garage and have it looked after.  Putting it off is going to cost you big money and is dangerous.


Cost to Replace a Torque Converter


If you are positive that you have a bad torque converter, than replacing it is a must.  Torque converter replacement cost is going to depend a lot on what type of vehicle you are driving.  In general, a front wheel drive vehicle is going to be more expensive from a labor point of view and could cost anywhere between $300-$1000 depending on the vehicle.

Torque Converter Problems

If you are going to attempt to replace the problematic torque converter yourself, than you certainly are going to be saving yourself tons of money.  If the vehicle that you are attempting to fix is front wheel drive, than it’ll be more difficult to do than a rear wheel drive.  This is due to the transmission location.  99% of the battle is just getting to the converter.  After that it’s a pretty simple fix.  Just a few bolts, slide the converter off of the input shaft, and tighten it back down.  If you’ve never done this before try and start at the beginning of the weekend to give yourself plenty of time and you can save yourself a ton of money.


Posted in tech

4L60E Transmission Problems

The 4L60E transmission is the direct descendent of the 700R4, and as such already had over a decade of refinement put into it before it ever even made it into production.  This means that even the early ones were pretty good from day one of their production life.  While there have been many case changes and internal changes throughout the years.  Ok, time to stop rambling.  Lets get into 4L60E problems and how to troubleshoot them.


4L60E Troubleshooting

It is important to understand a few things about how an automatic transmission works.   There is fluid that goes through the 4L60E that has three jobs:

  1. Lubrication
  2. Cooling
  3. Energy movement

That’s a lot for one fluid to handle.  Motor oil is only responsible for lubrication and cooling and is changed way more than transmission fluid.  Tranny fluid is one of the most neglected items of vehicle maintenance.  So before you go crazy thinking about what part may be giving you a difficult time, try making sure that the fluid isn’t the culprit.  This is especially true if you’ve recently towed something or been racing.  So if your 4L60E is acting funny after you’ve done one of these things, why don’t you just go ahead and change the fluid just to be safe.

Here is a good write up on low transmission fluid signs.

This is a good writeup on taking care of a tow vehicle


If the 4L60E is not shifting through the gears like it should be and the service engine soon light comes on than you’ve probably entered limp mode, limp mode is gear 2, 3, and reverse.  It will have no overdrive and no first.  The first thing that I would check is whether or not is is getting power from the ECM, and whether it is sending a signal back to it.  It’s way more likely that this has happened than you have a major issue.

If it isn’t an electronic issue causing limp mode, it’ll be a mechanical one.

If you find that your vehicle is vibrating at highway speed, this is often caused by a loose torque converter.  You’ll probably find that you’ll get this feeling at particular rpm ranges.   For instance, maybe you’ll feel a shutter from 1800-2000 rpm, but the engine will be fine above or below this range.  That is either the torque converter or harmonic balancer.  Make sure you aren’t confusing the shutter of a poor running engine with the vibration of a transmission with a loose converter.


Common 4L60E Problems

4L60E goes into neutral when shifting into third gear

This is one of the most common problems with the 4L60E.  It is pretty easy to diagnose.  The vehicle will shift from 1’st gear to second gear with absolutely no issue whatsoever, but than it acts like it has shifted to neutral.  The engine is usually under a pretty heavy load at the time, so it’ll tend to redline before you realize what happened.  Good thing these engines have rev limiters!  It can be a pretty scary feeling.

This is caused by a burned out 3-4 clutch pack.  And, the 3-4 clutch pack is done in by the 3-4 piston.  There is a giant rubber O-ring around the piston that will shrink due to heat and age.   Nearly everyone is going to have to take it on in for a rebuild.   Replacing the clutches in an automatic transmission is not a job that is easily done whatsoever.  There is a lot that can get messed up in the 4L60E

4L60E has forward gears, but no reverse

This is also a pretty common issue with the 4L60E.  More than likely the reverse input snap ring has sheared or snapped off. It can also be caused by the sun shell breaking.  The most common problem is probably going to be the low reverse clutch pack.  The booster valve could also be an issue.

Below is a pretty good video on common causes of 4L60E reverse going out.


Harsh shifting

Many people will bring their vehicle in and complain that the transmission is shifting really hard between first and second gear.  This is another really common problem with the 4L60E.  It would probably be a good idea to check the throttle position sensor and see if it is within it’s normal operating parameters.

Here is a good article on TPS issues.

Below is a good video on TPS diagnosis.


If you’ve had problems with the 4L60E after a rebuild, check this article from

Whatever is going on with your transmission, I hope that you are successful in fixing it, and you don’t end up losing an arm and a leg on repairing your 4L60E.  Good Luck!

Posted in 4L60E