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Old 05-23-2007, 09:58 AM   #1
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Question Compression numbers question

I already have sourced a used 1.6L to swap into my car, but I was thinking about my compression number a bit and I am starting the think that the problem is just a valve problem that a head swap would fix. Here's why:

dry compression 90-181-185-90
wet compression 95-185-189-95

If it were rings, shouldn't compression increase more with the wet? I added a tablespoon of oil on the wet test.

I ask b/c it would be much easier to just swap in the head. Thoughts?
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Old 05-23-2007, 10:15 AM   #2
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I bet you've got burnt valves. Pull the head and see, you've got nothing to lose at this point.
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Old 05-23-2007, 10:30 AM   #3
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Most likely - unless you have big damage on the piston side. You could double the oil and see if it comes up more- though I agree- pull the head and look. You know you've got problem and it won't take but a few minutes to get the head off and see.
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Old 05-23-2007, 10:36 AM   #4
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Quote:
Originally Posted by sbrian2 View Post
I bet you've got burnt valves. Pull the head and see, you've got nothing to lose at this point.
I was thinking the same thing as car was not running rough, just blowing smoke. Also no audible knock and AFRs in the 11s. I'm thinking that the timing was off enough to keep my EGTs too high for too long.

Time to put in an EGT gauge while the manifold is off .
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Old 05-23-2007, 10:37 AM   #5
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Either way the head needs to go if the pistons are bad. So pull the head on prelim, and inspect it. Like everyone has said you have nothing to lose there.
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Old 05-23-2007, 11:36 AM   #6
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depends how bad the piston rings are... the oil from the "wet" test could be draining right through.

A leakdown test will tell you immediately if it's the valves or not. you'll hear air coming out of them when they're closed...
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Old 05-24-2007, 01:58 PM   #7
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can you just buy a new head if the valves are burnt? what's the most cost effective way?
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Old 05-24-2007, 03:23 PM   #8
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rebuild with 3 angle valve job could run 400-1000 dollars depending on what he gets done parts etc. FWIW BGR my piston was totally smashed on the ring lands and it still showed great improvement with oil in it. So i am voting for headgasket failure, and maybe burnt valve but i doubt that one more every minute. Stock HG is only reliable up to 15 psi with stock bolts etc. you where pushing what 17-18 psi, think about it. i think that was what i heard but i am unsure.
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Old 05-24-2007, 04:38 PM   #9
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