2wheelhunter

i did a compression test on my friend's '00 civic si. the engine has about 90k miles. the reading was:

cyl 1 - 115
cyl 2 - 110
cyl 3 - 120
cyl 4 - 115

i searched for the correct figures and i saw that other people were putting out about 200psi, the car seems to pull alright but has a bad smell of burning oil with moderate smoke. now i live in NY where elivation is a little higher and i know that numbers can fluxuate but just how much? are these numbers okay or are the rings going to ****?

drtysohc

That is definately low man, but at least they're even. Check it again and make sure that you're doing it right. Make sure the throttle body is open, and you crank it long enough to get a peak reading. (this will usually take a few compression strokes)


good luck, hopefully you were doing the test wrong.

2wheelhunter

it was a peak measurement but the throttle wasnt all the way open this could be why

Libertariat

Yes, the throttle needs to be all the way open. That's why it's low.

I'm sure you'll still get even numbers when you test at WOT.

drtysohc

I was going to say...it is very uncommon to have every cylinder read that low.

gsrhatch2356

the throttle not being open will effect your readings but dont know that it will be that bad. for someone in your case I would try to get hold of a leak down tester it will shoot compressed air into combustion chamber via sparkplug hole. just make sure that both valves are closed and then if you hear air in oil pan you know its rings, tail pipe-- exhaust valves, intake-- intake valves. anyway you get the point. thats what I would do and check your base timing cause when there all that close a tooth or so off on timing belt will give you the same readings

95dxsir2

get a small oil can and put oil 3-4 cap fulls and try it again, i don't think the elevation and having the throttle slightly open will cause these low #'s. good luck, but it appears to be rings. try removing the breather line from the valve cover, if you have smoke coming out, thats enough evidence

gsrhatch2356

I am just wandering what the breather line has to do with compression and also try to be more specific on what you are talking about when you say smoke coming out( after you do what, and what this indicates)

95dxsir2

i'm not a teacher, but a mechanic, so bare with me.......when compression rings are "bad" (blow-by). Oil will be introduced into the cumbustion chamber=blue smoke. Since the compression rings are bad and not good enough to keep the (compression) air/fuel/oil mixture in the chamber when tdc occurs, it will seep into the crankcase. If you (anyone) remove the breather line in this case, smoke would be coming out (burnt air/fuel/oil mixture).
ok, back to my jim n pepper, expletive my brain is hurting


and having the throttle open or closed don't mean ****, and when checking for bad rings with a leak down, remove the oil fill cap - listen for air.

gsrhatch2356

What you said is very true and even though that could be the case with this vehicle. that test could be inaccurate on other occasions due to the fact that the compression rings could be could and the oil ring bad which with your discriprtion it wouldnt go back into the crankcase and yet still burn oil and you wouldnt think it is the rings cause you didnt see any come out of the breather tube. but still a good explantion and never thought of that but still a worst case scenerio and would really only happen if all the rings are bad (compression and oil rings)and probally would check for actully air being forced out breather tube.

95dxsir2

just using the compression results the op has to determine route cause. I've seen bad oil control rings, but still have excellent compression and leak down. Very strange, but it happends