Timing Chain Jumped Symptoms and Diagnosis

Of the many things that can go wrong with and engine, the timing chain jumping can be one of the most frustrating problems to have.  Depending on the motor, it can cause all sorts of problems. They require a lot of mechanical skill to replace.

Signs a Timing Chain Has Jumped
A typical modern timing chain that you’d see in a dual overhead cam vehicle


How Your Timing Chain Works

The timing chain connects the crankshaft to the camshaft(s).  It keeps them running in sync.  It ensures that the piston is close to or at top dead center at the moment of combustion.  If a valve is open or the plugs don’t fire at the right time the air and fuel that have entered the combustion chamber are not going to ignite.

Most timing chains use a tensioner to keep them tight and to keep them from jumping. If something happens to the tensioner, it can cause the timing chain to jump prematurely.  It’s always a good idea to really listen to your engine every now and then, so you know what the signs of a timing chain getting ready to jump are.


Signs a Timing Chain is About to Jump

There’s not a whole lot that you can do for a motor once the timing chain jumps.  It’s very important to catch this before it happens.

The good news with chains is that with a good ear you should be able to detect this coming.  The timing chain will begin to make a clacking sound.  With the extra slack that develops in it, it’ll often clack against the timing chain cover.

It’ll sound a heck of a lot like a metal on metal washing machine.  That may be a strange analogy, but if you can imagine what that would sound like, you’re getting close to what a timing chain that is about to jump sounds like.

At normal cruising speeds you’re probably not going notice any sort of a sound at all.  Far and away the best time to identify the sound of a timing chain that is about to jump is going to be listing to it when you first start the vehicle.

If the timing chain is not metal, it’s really a timing belt, and they can be a lot more difficult to tell if they are going bad.  Timing belts are a normal maintenance item on a vehicle.  The best thing that you can do is have the vehicle timing belt service performed on schedule.


Timing Chain Jumped Symptoms

Here are the symptoms of a timing chain that’s jumped.

  • Noise–  A good indication that a timing chain has jumped is going be noise.  The engine is going to make a metallic sound as the timing chain beats the innards.  It’ll typically be a rough rattling sound.
  • Performance Decrease–  The engine timing is going to be affected when the timing  chain jumps.  As stated above, the timing chain is essential in making sure that the upper valve train is synced up with the crankshaft.  If it’s even a little off, you may experience a performance loss.
  • Service Engine Soon–  Your vehicles ECM may or may not have enough input from the engines sensors to detect that the timing chain has jumped.  But, it often does.

What You Should Do if the Timing Chain Jumps

If your timing chain has jumped, it needs to be fixed right away.  It’s only a short matter of time before it’s going to jump again or break all the way.  When that happens, it’s very likely that your engine will need a complete overhaul.

It’s a LOT of work replacing the timing chain yourself.  Depending on the vehicle, you may need special tools made just for the job.  Have the vehicle towed to a mechanic who can replace the timing chain for you.


Timing Chain Broken Symptoms

If your timing chain breaks the most immediate thing that you’d notice is that the engine doesn’t run anymore.  The camshaft(s) aren’t going to turn, which means that only the lower part of the engine is going to turn.  In most cars that would mean the crank and oil pump.  Everything above that typically relies on the timing chain to turn.

Now, if the timing chain is broken, the vehicle will not run.  The real question is whether or not any permanent damage has occurred.  The valves are going to get slapped by the pistons.  This will cause them to bend.