Hi,

I just did the test. 169 in the rear and 167 in the front. Looks like all this was for naught.

I looked at my bill from the repair centre and it says right on it that I needed new head gaskets!

I was right there when he sprayed a fluid on the fins at the head gasket area and the motor sputtered......

Must have been snake oil I guess

 

Compression test or leak down will tell you. You can usually hear it make a spitting noise. Usually Evos were bad about the base gasket leaking oil and it could be fixed by using a part called the oil fix.

 

Was compression test done at operating temperature? Op temp may be significantly lower. I always do a leakdown test after; you can pass a compression test but still have a leaky valve. Head gasket is fine at that PSI. The compression test opens and closes the valve (cranking) while the leakdown is at TDCC only.

 

Thanks,

Yes, I warmed the bike up to normal operating temp before doing the compression test. I was surprised that the compression was so high, given that anything over 90 lbs is satisfactory.

How does one perform a "leak down test"?

thanks
again

andy

 

- you'll need the tool which can pressurise the combustion chamber
and measure the fall ("leak down") in pressure over a given period of time.

.

 

You wont be able to measure it, but you may be able to use your compression tester, if it has a quick connect for your air hose. Just listen and feel for a leak. It will give you an idea anyhow. Be aware though, that the air will push the cyl to BTC. If its in gear, the bike will move.