If your Mercury Grand Marquis is leaking water, it could mean a few different things are happening. Some water is completely acceptable. It depends on the situation. It really depends on where you’ve found it, and if it is really water.
Coolant or Water?
If you are trying to figure out if your Mercury Grand Marquis is leaking water, the first thing we need to do is determine if you have coolant or water underneath of the vehicle. Coolant is sweet smelling and is typically orange, green, or pink. It might not seem possible to determine the color of the liquid in question, but a paper towel allowed to soak up enough coolant definitely will begin to show pigment. Water is tasteless and odorless.
If it is engine coolant, it’ll be coming from different places than water typically will, and will need to be addressed separately. There is a section further down the page with common radiator leak causes, if it’s coolant that you found has leaked from your Grand Marquis.
Leaking Water Causes: Mercury Grand Marquis
Here are the most common reasons that water may leak from your vehicle (not coolant, that is covered below).
Air Conditioning System– Your Grand Marquis’s A/C system leaks water directly underneath the engine bay as a byproduct of its operation. If you there is a big puddle of water under the vehicle, it may be because it was left running in place for a while. Fifteen minutes on a hot day can be enough to get a trail to the rear wheels. This is completely normal and should not be cause for alarm.
Exhaust System– Your Grand Marquis’s engine creates steam as part of the combustion process. It is way more noticeable in the winter time when white smoke billows out of your exhaust pipes. Water can also leak out of the exhaust as this happens. A little water is completely normal. A lot of water leaking out of the tail pipe is certainly a cause for concern.
Some Water Under Your Grand Marquis Might be OK
Your Grand Marquis’s air conditioning system is going to produce water as a product of the cooling process. This is normal. It will usually produce moisture just behind the rear tires. This is harmless water, and is nothing to worry about.
Mercury Grand Marquis: Leaking Cooling System
If you’ve found coolant on the garage floor, and not leaking water, that’ll be an entirely different set of circumstances causing the leak.
It is possible that your coolant system could be leaking water. If you, or whoever had the vehicle before you filled the cooling system up with water instead of antifreeze coolant, it could be leaking water. The problem is that water will freeze in the winter time and cause the engine block, heads, freeze plugs, or some other part of the engine to freeze up.
Common Places Your Cooling System Leaks Water
If your Grand Marquis’s cooling system is leaking water or coolant, here are the most common places that it may be leaking from.
Thermostat Housing– The thermostat is a small device that acts as a barrier that lets coolant into the engine only when it reaches a certain temperature (usually a bit over 200 degrees). There is a housing that bolts to the block that holds the thermostat. It’ll have a radiator hose attached to it. It is very common to find that your Grand Marquis is leaking water or (hopefully) coolant from this location. It’ll be toward the front of the vehicle, further up than where the A/C condensation would be.
- Radiator– A bad radiator can will cause antifreeze to leak onto your garage floor or driveway. If you go looking for it, and your Grand Marquis is equipped with electric fans, treat them like they could run at any time just to be safe.
- Radiator Hose– There is a rubber hose that connects the radiator to the thermostat housing, and another one that connects the return from the engine block. These hoses can leak coolant from them as they dry out and crack.
- Head Gasket– Your Grand Marquis’s head gasket is designed to fail before permanent damage is done to the block or head when overheating. This does not mean that the head gasket will only fail if the engine has overheated. If the head gasket is blown, it could let coolant out of the engine onto the ground. It could also let coolant into the exhaust, which would manifest itself as white smoke.
- Cracked Head or Block– This would be the last thing that you’d want to look at on this list, as it’s far more likely that one of four issues listed above would be causing water to leak from your vehicle.
Conclusion: Grand Marquis Leaking Water
Water itself, is often not a problem at all. If you have a coolant leak, that’s another thing entirely. Good luck diagnosing your Mercury Grand Marquis’s water leak. If there is anything you would like to add, please leave a comment below.