I have a 2003 Cobra. It has an aftermarket throttle body and exhaust. It has 49k miles I have not raced it. Over the last few years the car is seldom driven or started. It passed smog in September 09. I had it sold. I pulled it out of the garage and noticed that it cranked longer than it usally did and when the cooling fan comes on sometimes the idle dips like it wants to stall. It goes back to normal idle right away. The car still pulls hard and I see no smoke nor can I feel it dropping a cylinder. The check engine light has not come on . The buyer wanted to do a compression test. We took it to a shop of his choice. The passerger side had between 145-150 psi in the cylinders. The drivers side first two cylinders were 130 -135 the rear two were 95 and 65. The plugs look the same. They all look rich to me. the rear cylinder was hooked up to air. I don't believe that top dead center was found as air could be heard in the exhaust tail pipe and the spark plug hole next to it. Any thoughts? Thanks for your input.

 

Sounds to me like bent valves,,,,,,,OR carbon build up holding the valve open,,,,,,OR blown head gasket/cracked head, Cracked pistons, broken rings,,,,,,is the car running rough at all? Loosing coolant? Burning oil?

These are worse case,,,,,,Hopefully it isn't those,,but it dosn't sound good!!

 

The funny thing is that the car runs strong. It is not overheating. The only thing that I noticed since I last drove the car in September is that sometimes it cranks and doesnot want to start right away like it is not getting fuel or its flooded. The other thing is that sometimes when the fan comes on it bogs down the engine. I was hoping that perhaps carbon is not letting the valve close or the rings were not seating well. In the past year except for getting a smog check in September the car has not been driven much. Thanks for your input.

 

I agree more than likely its a head gasket or a piston. Typically if its a valve, you would have 30psi or less, due to the fact that if a valve is bent it never fully closes,there for it will not hold pressure. good luck let us know if we can help out.

 

I was going to say that also,, may just be some sticking rings,, take it out and drive it normal till up to operating temp,,then romp on it a few times, but don't go to wild,,if you can drive it at least 50 miles. Bring it back home and let it cool till you feel like you can touch without getting burned,,,do a compression test on it,,if it reads higher than the last one then there is your problem,,,needs to be driven!!! Hopefully that is all it is,,you never know, stranger things have happened!!!!