Quick Question

[zak_62]

Hi~
Just curious, but if a cylinder is consuming oil, how do we know if the oil is from the oil control ring or the valves?

[lotusguy]

zak_62 said:

Hi~ Just curious, but if a cylinder is consuming oil, how do we know if the oil is from the oil control ring or the valves?

Hi,

There are a couple of ways. Using a leakdown tester is one. Doing a Dry, then Wet compression test is another.

With the leakdown tester, you can pressurize the engine and wait for the pressure to fall off. While doing this, you can take an automotive stethoscope and actually trace the sound of leaking air.

With a compression test, you first do a test Dry and record the results. Next, you shoot a couple Tbl. of Motor Oil into the sparkplug hole and run the test again. If the two sets of result differ markedly, with the Wet test results the higher of the two, your rings are suspect as the oil added in the Wet test temporarily seals the rings resulting in a slightly higher pressure than the Dry test. If the results don't change, but are below spec, then suspect your valves and guides.

The compression test series is easier because for the leakdown test to be valid, you need to hand rotate the hot engine to close the valves on each cylinder as it's tested, with the compression test, you simply crank the engine until the comp gauge records it's highest level (of course warm engine and throttles fully open). Happy Motoring! ...Jim'85TE

[rlearp]

Jim has the best way. But, the old method works pretty well too.

If you leave the car sit for a day or two, start it up and blue smoke comes out then it is seeping past the guides and burning on startup. More seeps past, down, and into the combustion chambers while it sits around thus leading to the blue haze when you fire up.

Just a rule of thumb but it works lots of times.