Contour Enthusiasts Group Archives Forums General Troubleshooting Complete loss of compression (2.5 V6)

I have a 1999 cougar with 115,000 miles (meticulously maintained since 35,000 when I bought it in '01).

Today I went to start it and it had compression for the first turn of the crank, then nothing. The starter spins the engine over easily with almost no resistance (from normal compression). Taking out the oil cap and cranking shows the exhaust cam on the front bank turning so I know at least the chain from the front side didn't break. My guess is that both of the chains simultaneously jumped and I've bent a lot of very expensive valves.

Has anyone ever heard of this failure?

More likely it's flooded. A faulty ECT can cause this during warm weather.

flooding doesn't usually cause COMPLETE loss of compression, if it's severe it usually hydrolocks the engine.

If you ever hydrolock a car (Can be caused by stuck open einjector) pull plugs and crank over BY HAND to expel the fuel (never crank over with the starter as it blasts the gas out and is a great way to start a massive fire.

I have seen flooding causing complete loss of compression on these engines several times. It was also common on Lincoln Continentals with the closely related 4.6 DOHC engine (although I have never seen it with the nearly identical engine in a Mark VIII).

Often you can get it running by cranking with the throttle held wide open (which shuts off the injectors).

Ocassionally, I have needed to pull the front spark plugs and squirt a little oil in the cylinders to restrore compression long enough to get the engine running again. It will be a little rough for a moment or two untill the other half of the engine restores compression and the oil burns off.

If flooding did cause this problem....then I would look for what caused the situation in the first place..defective irmc, etc.

If it sounds like it has no compression then the most common reason would be oil-wash caused by flooding. The extra gas washed the oil from your compression rings. The first thing to do is to check for gas in you lower intake. If you smell it or see it you have to find the source, here are some items to check,

Fuel pressure regulator vacuum line, sometimes the regulator leaks fuel from the vacuum port.

ECT sensor. A bad sensor will cause a warm engine to flood.

Leaky fuel injector (real bad leak).

Once you find the fuel source, correct the problem and dry up the gas in the manifold, then remove your plugs and squirt a small amount of clean oil into each cylinder. (Don�t go crazy here; just a few drops will do ya).

Crank the engine for a few seconds to distribute the fuel. Dry and install the plugs and crank her up. It will smoke until the extra oil burns off.

I have never seen or had a reliable report on any timing chain jumping a tooth. Look at a chain, it just can�t happen. I have seen chains break, sprockets strip and cams break, but never seen a chain that skipped.

jeff

why not just hold your foot down on the gas(clear flood) and crank for awhile. that usually clears the cylinder of gas, then release the pedal and sometimes slightly depress it(added air) it will usually start.

Check spark, check injecter o rings, check to see if the injectors are leaking fuel...pretty much everything every one reconmended......


If flooding casued it thoes would be your logical choices to start with.

Good Luck.

Lupe

Well, it was the oil wahdown caused by a fuel leak (evidently it was slow enough that it took two days to cause the issue) I haven't found the leak YET though as I have to rip apart a lot of things first..

Pulled the front three plugs, oiled the cyls put the plugs back in cranked (foot to the floor actually worked better as with the throttle open it'll bring in a lot more air to help blow out any fuel residue) and she eventually fired, smoked for quite a while, took it for a quick ride to make sure it was fully warmed, then let it cool down and changed the oil/filter. Now it runs just as good as she did before the incident with no smoking at all..


Did price out a set of injectors (about $396.00 from the dealer (OUCH! ) Anyone know of a place that sell the right injectors for a better price?