Rob
I have a 2005 Dodge Durango Hemi with only 37,000 kilometres on it that makes a weird sound after I shut off the engine: it sounds like a flushing toilet.
I keep the truck in my garage to keep track of leaks from the engine, but nothing is showing up.
Last week I backed out and shut off the engine immediately only to hear that sound again. My Chrysler dealer looked at this problem last year, topped off the coolant and told me not to worry about it. After this last incident, I am worried. Back to dealer, service manager looked at it, mechanic and a third person checked it but none of them had any idea what was causing the problem. Can you help?
Dave
This is a tough one, Dave. You have described the classic symptoms of a leaking head gasket. Here's where the tough part comes in - Chrysler Hemis are not known for head gasket problems.
But you should never say never because as sure as Murphy was an optimist, anything can go wrong.
I cruised around a ton of web forums and there are many other vehicles out there that have leaking head gasket problems. So, for as much as Dave has asked the question, this article is for all those out there with engines that make sounds like the first stage of a toilet flush.
This sound is created by the huge pressure difference between the cooling system and the combustion process taking place inside the combustion chamber - literally the movement of the fluid and/or the movement of bubbles in the coolant. What makes matters worse is that the cooling system passages are adjacent to the cylinders and the combustion chambers.
Normally, a cooling system operates with a pressure of about 15 pounds per square inch (PSI). Combustion pressures run typically at 500 PSI. With these figures, it doesn't take much math to figure out that any sealing problems between the cooling system and the engine cylinder will result in combustion gases being forced into the coolant, and what makes this worse is that any residual pressure left in the cooling system, after engine shut-down, will force its way into the engine cylinder across the leaking head gasket. This is the toilet flush you hear Dave, the bubbling back and forth across the gasket leak.
However this is not to say that this is the only possibility. With "V" configured engines - V6's and V8's - a second ingredient can be thrown into the mix; that is, the intake manifold gaskets.
In addition to containing most of the major intake components, intake manifolds also direct coolant across the engine from one cylinder head to another. Leaks here can cause toilet flushing but often there is evidence lying on the garage floor, because this type of fault is external leakage. A head gasket problem is usually an internal leak - one that spits coolant out the exhaust in the form of white steam (often misinterpreted as smoke).
How do you tell this is going on? You need a cooling system diagnosis.
A device that looks like a giant test tube is filled with a liquid that is reactive to exhaust gases - usually carbon dioxide (CO2). Typically it's blue but in the presence of CO2, the fluid turns yellow. With the engine running, the cone-shaped end is placed in the radiator or coolant expansion tank filler neck and gases are pulled through the liquid. Any combustion gases present in the coolant will instantly turn the fluid a different colour.
Another neat trick will involve a shop that has an exhaust gas analyzer. With the engine running, and the radiator or expansion tank cap removed, the test probe is placed above the coolant. Any gasses will be picked up and displayed on the meters of the analyzer.
This is the easy part.
Dave, the hard part comes in two stages, if indeed there is exhaust gas in the coolant. First, the repair is very lengthy and second, get out a very thick wallet. There is good news however, because this repair will also cure hip dysplasia caused by a wallet that has too much money in it.
I'm afraid it's going to take more than a plunger to clear up this mess.