Oil on valve covers

[bcrandall]

For the last few years I've noticed a small amount of oil on the top of the valve covers. I took it in to a mechanic thinking the gasket needed to be replaced and he didn't think it was coming from the gasket. He thought maybe it was coming from the PCV valve or fill lid and mentioned something about compression. It's a 1995 SS and runs great with only 350 hours on it. It doesn't loose hardly any oil, just enough to smell bad and get into the bilge. Any ideas?

[mrbobolina]

Is the oil on top of both valve covers or just the one with the cap? Do possibly mean the oil is coming from the valve covers and seeping down?

[scuff97]

did you replace the PCV valve? also check the vent line on the opposite valve cover

[DanielC]

What Scuff said. Is this a GT-40 Ford engine? If so, there is a hose that goes from the side of the oil filler pipe, to this underside of the flame arrestor. If your PCV system is operating correctly, the engine should draw air into this hose, the crankcase of the engine should be at a slight vacuum.
Check for vacuum at this hose, at idle, and part throttle operation. At full throttle, it is normal for engine blow-by gases to be more than the PCV system can handle.
It is also possible the rings on the engine are worn. Your mechanic can do a compression test, or ideally a cylinder leakdown test.

[bcrandall]

I have passed this information on to my mechanic. We'll see what he comes up with after he does a compression test. It is a GT-40 EFI. Wouldn't I notice performance difference if there were issues with the compression/ rings? thanks.

[bhectus]

possibly but most likely not unless compression was really low.

[mrbobolina]

You would notice differences depending how off your compression has become wich is also code for how extensive your problem is.

I ran all summer last year 6 adults and kids single skiers, boarders and tubes, no problems. I had a minor head gasket leak that I intended to take care of in the winter. I did a compression test, which by the way you can do yourself. The tool is $40 and up at Pep Boys. You take all of your plugs out put on teh compression guage in teh plug and grank the motor over a few times. The compression guage tells you what your compression is. It is about as hard as changing your spark plugs.

Anyway, my compression was reading 100-120 on 6 of 8 cyliders. Two of the cylinders were reading 0-90/0-90. I had two lifters sticking. I took the heads off the machine shop did he leak down right in front of me and I was leaking in 7 of 8 intake valves and all of my exhaust valves were fine. Turns out I also had a slightly bent valve as well. All of this has nothing to do with why you have oil on your valve covers, only to illustrate you can run just fine (while not optimal), and fail the compression and leakdown test. Of course had I not caught all of this we all know I would have broke down at sunset in the middle of the lake and no cell phone reception.