#3 Cylinder Compression Problem

[tekjones83]

I have a 1995 Mighty Max 2.4L Auto. The compression is good across the board at 120 psi except for number 3 cylinder which is 0 no compression on my compression gauge I check it 3 times to see and you can hear the motor spin over faster when comp gauge is in the number 3 cylinder. The motor spins slower and you can hear the compression building into the gauge on the other cylinders and see it on the gauge as well. When it is running it is vibrating at idle and when pressing on brake pedal cause its a automatic it almost wants to cut off so i have to put it in neutral and then switch it to drive when the light turns green but when i get on it. It runs smooth and strong....So big question what is wrong here?

[noahwins]

Have you checked the head gasket?

[tekjones83]

well to a point there isn't any oil in the water or water in the oil. so far so good.

[tekjones83]

I still have the dead #3 cylinder but I haven't cracked the valve cover off yet to see under it to see if maybe something is broken hopefully maybe it is lol but when it is running i can hear a tapping noise coming from the valve cover area not in the bottom end thank god lol so any suggestions will be great.

[tekjones83]

Well I cracked the valve cover off the engine and nothing is broken and spun the engine over by hand. So I am thinking I have bent valves or burnt valves or a cracked head won't know till I pull off the head on the engine but it will be a while before I do that since I am driving it around for now. Any suggestions on a easy fix or anything else on the matter.

[340D]

My compression gauge hose will disconnect and can be put on air hose. If yours does that you can blow air in that cylinder and see where it comes out. Make sure both valves are closed. If it is the exhaust valve air will come out the exhaust pipe, intake if its the intake valve and crankcase or radiator if head gasket.

[Andy 2]

it could be something simple like a sticky valve.

[pennyman1]

or jet valve

[Andy 2]

That would explain why it runs fine at higher rpms. The little jet valve hole can't dump the compression fast enough to misfire. The tapping noise at idle could be the tappet striking the end of the stuck open valve.

[pennyman1]

the jet valves also are out of the circuit above 1/3 throttle or thereabouts by design, eliminating the path for the leak