Got bored at home and did a compression test on a dx motor (d15??) and got the following,
1=115
2=120
3=125
4=170
I left cylinder 4 alone because it looks ok. Added a drop of oil to the others and it raised compression right around 170. If I'm not mistaken, this means the piston rings are bad. The question I have is why doesn't the motor burn oil or blow dark smoke out the exhaust? Oh and I use 10w-30.



[Modified by hmonglonertim, 2:35 PM 8/23/2002]

 

sometimes pouring oil in chambers to retest just makes pressure go up because oil now takes up space and there is less cyl volume, depending how much oil you put. The idea behind pouring oil is to sit on top of oil ring to see if it seals, sometimes its your compression rings that are shot and not oil rings. In your case it sounds like your valves or at least seals may be shot. The way to do a more precise test is to pour oil check, read pressure add even more oil and check again if pressure remains the same with even more oil then its your valve seals if it keeps going up its your rings. Obviously you wouldn;t be doing this test if you have access to a leak down tester and air compr.

Greg

 

Thanks for the reply. Can I do the test you described with a compression tester or would I have to do it with a leak down tester?

 

compression tester where you check with little oil then add more oil and recheck.

if you have a leakdown tester, I wouldnt have told you to do the other way

greg