CroCivic91
Dec 1, 2004, 10:07 AM
What can cause a compression test to show low compression on any cylinder?
About half a year ago I went to check the compression at a local Honda Dealer, and they said 3 cylinders were OK and one was very bad. They said they poured some oil inside each cylinder and I got results of about 11:1 on 3 cylinders and about 8:1 on the 4th. (I still have the results card)
Since then I read a lot about cars and how engines work and all the different things under the hood, and it mostly said: bad compression is mostly caused by worn piston rings. But wouldn't that cause oil to enter the combustion chamber, and wouldn't that cause my spark plugs to be oil fouled? I chanegd spark plugs about 2 months ago (after about 4-5 years that my brother never bothered to change them) and they turned out to be looking quite well, except for their excessive wear (there are sites out there with pictures of spark plugs and how they should look if this or that is happening inside, like oil leaking... ).
Anyway, what happens to the car is - it lacks a LOT of power (I guess it should be a clogged catalytic converter), and it idles a bit rough, rpms going up and down all the time (I don't have a tachometer, but you can notice it not idling steady), for which I guess the reason should be clogged PCV and EGR valves, which I hope to clean in the next week.
Well, sorry for the long question, but I'd just like some of your opinions on what's going on. Oh, and I read somewhere that non-adjusted valves could cause compression to be low (valves have NEVER been adjusted).
Thanks, Kresho
About half a year ago I went to check the compression at a local Honda Dealer, and they said 3 cylinders were OK and one was very bad. They said they poured some oil inside each cylinder and I got results of about 11:1 on 3 cylinders and about 8:1 on the 4th. (I still have the results card)
Since then I read a lot about cars and how engines work and all the different things under the hood, and it mostly said: bad compression is mostly caused by worn piston rings. But wouldn't that cause oil to enter the combustion chamber, and wouldn't that cause my spark plugs to be oil fouled? I chanegd spark plugs about 2 months ago (after about 4-5 years that my brother never bothered to change them) and they turned out to be looking quite well, except for their excessive wear (there are sites out there with pictures of spark plugs and how they should look if this or that is happening inside, like oil leaking... ).
Anyway, what happens to the car is - it lacks a LOT of power (I guess it should be a clogged catalytic converter), and it idles a bit rough, rpms going up and down all the time (I don't have a tachometer, but you can notice it not idling steady), for which I guess the reason should be clogged PCV and EGR valves, which I hope to clean in the next week.
Well, sorry for the long question, but I'd just like some of your opinions on what's going on. Oh, and I read somewhere that non-adjusted valves could cause compression to be low (valves have NEVER been adjusted).
Thanks, Kresho