Compression test results

[unome]

Hi,
I've got an M42 with about 160,000 miles. I ran a compression test on it, and got these results: 190, 205, 200, 200 dry and 230, 225, 220, 215 wet. What exactly is this telling me?

I've been getting some excess crankcase pressure (some oil seeping from around the filler cap), so I'm guessing it's time for rings.

If so, is this a job that I can do without doing a complete rebuild on the engine? I really don't want to spend $2000 on it.

Thanks for your input!

[nickmpower]

Those numbers look alright. If you untwist your oil cap while the engine is running and the crankcase pressure blows it off something would be wrong. 160k is nothing for these motors. I bought an engine with around 70k. Turns out the engine had been run out of oil at some point and all the bearings were trashed. I did a leakdown test on the cylinders and they were all less than %5. Point is, you have to have serious issues for ring problems

[DesktopDave]

Those readings look great.  I'd figure you have a vac leak somewhere and the intake isn't pulling enough vacuum.  If you have an e36 it might be that separator valve.

[unome]

Thanks everyone. I'll start investigating other causes of the issue.

[nickmpower]

Are you sure its leaking around the oil cap? There could either be a problem with the cap, or it could just appear to be leaking. When you take it off and on some oil usually gets on the valve cover and you cant see it right away

[unome]

Yeah, I thought about that. I gave it a good wipe down, and the oil returned but not as obvious. When I remove the cap while idling, there is good vacuum and the engine stalls as you would expect. The oil must be leaking out after I stop the engine. I'll try a new cap.