burning oil

[blackjack]

generally speaking.an engine with a lot of mileage will show some oil deposit on more than one plug...i wouldnt be surprised to see a lower compression reading on that cylinder
bj

oil leak in that chamber will give high comp. reading!!

technically, its wrong to say it gives low reading!

[tomtom72]

Originally Posted by HADI-ZR1

oil leak in that chamber will give high comp. reading!!

technically, its wrong to say it gives low reading!

Hadi, not exactly. You do the comp test by just spinning the motor say five times at each cylinder. The motor is off & you turn it by hand w/a breaker bar on the crank pulley. If you got a way low reading at any holes you would then squirt oil to see what affect that has on a re-test....in theory if the rings are that bad the PSI will go up with the oil shot.

That's why I kind of like to see what the vacuum gauge says before I do a comp. test....it kind of points you in a direction rather than starting off blind.


Tom

Tom this is your opinion!
better make Leak Test to find out.

[blackjack]

Originally Posted by tomtom72

Hadi, not exactly. You do the comp test by just spinning the motor say five times at each cylinder. The motor is off & you turn it by hand w/a breaker bar on the crank pulley. If you got a way low reading at any holes you would then squirt oil to see what affect that has on a re-test....in theory if the rings are that bad the PSI will go up with the oil shot.

That's why I kind of like to see what the vacuum gauge says before I do a comp. test....it kind of points you in a direction rather than starting off blind.


Tom

thats what i meant...if you do a compression check when cold and you have more than,say,25% difference in that cylinder,you might have more serious problem than simply worn ring...i just didnt want to scare 72zr1;the fact that only one cylinder would be low is sometimes-did i say sometimes?-an indication that there is something wrong in that cylinder,other than normal wear...jmo
bj

[tomtom72]

Originally Posted by HADI-ZR1

Tom this is your opinion!
better make Leak Test to find out.

You're correct it is JMHO. That's why I'm partial to using my vacuum gauge as it can help point you to the next logical diagnostic test....it's not fool proof by any means. I'm lazy and hooking up a vac gauge is easier than doing a comp test and a leak down test...