Funky cylinder pressures - could use advice

[holley]

My SC has had water leaks ever since I bought it, now I've replaced all the pipework save the turbo lines around the back of the block, and it didn't lose any water. Anywho, it started running like crap and started using water, so I did a quick check with my basic compression tester, and got this:

#1--#2--#3--#4
75--162-148-145

Now #1 is obviously where the water is going in, but #2 is what I'm really worried about! Could that higher pressure be caused by a worn bearing causing the piston to come up higher than it should?

I'll be testing the S block this week, if it checks out ok I'll swap the engines whole as a temporary measure ... good excuse to get a common block

[aerosmith145]

did you hold the throttle body open during the test?

worn bearings shouldn't raise cylinder pressure.

[MarshallOne]

It's not worn bearings doing that. Maybe you got some oil getting in that cylinder or water/antifreeze.

[mo' parts]

Quote:

Maybe you got some oil getting in that cylinder or water/antifreeze.

^^+1

no.1 is probably busted.

of the many, many comp. tests i have done, holding the t.b open only made a slight difference. about 5psi+/- , same for a cold engine.

[87shelbyt2]

#2 cam lobes worn off? last adjusters spongy? either way it would seem the ex valve may not be opening for the complete duration or have enough lift. Just a guess...

[holley]

I did hold the TB open, and redid the #1 and 2 to make sure. The cam isn't worn, but one of the lifters is sticky when hot - I guess that could be it, lol ... seems dumb no that I didn't I think of that!

I guess I'll just have to pull the head, can't just yet as I've not got enough cash to pay for a new gasket and head skim ...

The thinking behind the worn bearing causing the higher pressure was if there was some play and enough momentum for the piston to come up higher.

Anyway, thanks for the input guys 5 heads are better than 1!

[GLHNSLHT2]

if the bearing was worn the cylinder wouldn't come up as high even though it wouldn't be enough to see on a pressure gauge

[holley]

thanks, I've not had experience with bearing failure yet (!) but thinking back to 2-stroke motorbike days, the thickness of a gasket made a significant difference in the compression, and I wasn't sure if the upward momentum could be enough to overcome the pressure ...