Cyl 1 was 180 Cyl 2 was 180 CYL 3 was 90

[needacar87]

Ok so over winter break i was about to do a new turbo setup to my talon, but before i order anything i wanted to check out the engine, so I did a compression test. Cyl 1 was 180 Cyl 2 was 180 CYL 3 was 90 and cyl 4 was 180. As you can see there a huge problem with cylinder 3. I was told it could be I have a bad cylinder or it can be something with my head. Also there is oil on the spark plug every time i check it. My question is what other test can i do besides tearing apart the engine to figure out what is the problem?

 

[94_eclipse]

Take out the plug on the bad cyl #3, get an oil can with some thick oil. Gear oil would work fine, put about 5 squirts in it. Put ## compression tester in and give it a few cranks, if it goes above your previous reading of 90lbs then you have a bad cyl. It could be just your rings are worn out.

Now if that does not do anything, chances are you have a bad valve that is not making a good seal. Either way it sounds like you are going to have to rip into the engine to fix. But at least that will narrow down what is wrong.

 

[1992awdlaser]

Doing that test isn't as accurate as everybody thinks. The oil will get on top of the piston and will cause the tester to show higher compression in all cases I have seen.

Take the valve cover off and rotate the cams so all the valves in that cylinder are closed. Make sure you have somebody hold the cams so they don't turn. Take the plug out of the cylinder. Put the one hose from the compression tester in the plug hole. Put air into the engine by hooking an air hose from a compressor to the hose from your compression tester. If you do that part without the cams being held in place they will likely turn from the air pushing on the piston. While air is in the cylinder see if you can hear it coming out of the exhaust or going into the intake manifold. If it is then there is a problem in the head. If the air is going into the cranke case there is a problem with the cylinder. To check the cranke case take off the oil cap and take the dipstick out. You will hear air in one of those two spots if it is getting in there.

 

[94_eclipse]

Doing that test isn't as accurate as everybody thinks. The oil will get on top of the piston and will cause the tester to show higher compression in all cases I have seen.

QUOTE]

That is the whole point? With the oil on the top of the piston, it will make a seal on the piston wall. Acting as a brand new set of rings and piston. If the compression goes up, then your piston and or rings are bad. If not then it is the valves that are bad, either the valves have a hole in one or the seats are bad.

 

[Bud92gsx]

Ok 1st id do the leadown test. make sure u know what ## doing. if not get it on alldata on a haynes book or sumthing. If you just want to take it apart go for it. tear it down, inspect it,order parts put back together, and fire it up. whatever you want.

 

[carbide]

I definately agree a leaqkdown tester is the most accurate way to find out whats wrong. JUst listen to where the air is leaking, and go from there. Could just be a head issue, then you caan just pull the head and save yourself the time of pulling the engine. Times like these are ones that often lead DSMers to say, "F@#* it, why not just rebuild the engine!"

 

[1992awdlaser]

Doing that test isn't as accurate as everybody thinks. The oil will get on top of the piston and will cause the tester to show higher compression in all cases I have seen.

QUOTE]

That is the whole point? With the oil on the top of the piston, it will make a seal on the piston wall. Acting as a brand new set of rings and piston. If the compression goes up, then your piston and or rings are bad. If not then it is the valves that are bad, either the valves have a hole in one or the seats are bad.

You aren't getting what I'm saying. The oil will sit in the dish of the piston and will raise compression numbers regardless if it is the rings or vlaves leaking.

 

[94_eclipse]

ahh ok i got ya now. I wasnt thinking about the dish in the piston holding the oil. Ive used that trick before but it was on flat or domed pistons i guess.

 

[needacar87]

I definately agree a leaqkdown tester is the most accurate way to find out whats wrong. JUst listen to where the air is leaking, and go from there. Could just be a head issue, then you caan just pull the head and save yourself the time of pulling the engine. Times like these are ones that often lead DSMers to say, "F@#* it, why not just rebuild the engine!"

thats what im starting to look in to. rebuilding the whole engine. Thanks for the advice guys

 

[Defiant]

Also there is oil on the spark plug every time i check it.

#3 has blown rings. Rebuild.