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Odd Compression Test Results

 
Old 09-20-2018, 05:59 PM
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Default Odd Compression Test Results

Performed a compression test today since I'm starting to compile a list of parts for a turbo project. Car is a 2005 with 150,200 miles. I've only had it for 2 years and 5,000 - 6,000 miles.
Engine was warm, all 4 spark plugs removed, fuel pump fuse removed, throttle held open while cranking.

Results:
Cylinder 1 - 190
Cylinder 2 - 218
Cylinder 3 - 220
Cylinder 4 - 265

Obviously cylinder 1 is low and 4 is high. Cylinders 2 and 3 seem to be normal. Why would cylinder 4 read so high? Cylinder 1 being low makes me think maybe exhaust valves? But from what I've read here on the forums, 06-09 are usually the ones with tight exhaust valves. I'll rent a leak down tester and see where its leaking from. Any ideas on these numbers?
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Old 09-20-2018, 07:51 PM
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Any chance your battery was running low by the time you tested #1? (Was #1 tested last?)
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Old 09-20-2018, 07:55 PM
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#1 was tested first, and then tested a second time at the end. Same results. Battery was fine.
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Old 09-20-2018, 08:52 PM
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Carbon build up ?
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Old 09-21-2018, 11:56 AM
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Try a wet test and see if there's a difference. Check and adjust all valves. Re-test.
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Old 10-07-2018, 08:04 AM
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Default Valve adjustment findings

Went ahead and performed a valve adjustment last night. Check out the before and after, some of these are really odd. Some exhaust valves were tighter than my smallest feeler gauge, which is .005". This poor car has probably never had a valve adjustment. Most of the intake valves were in spec. I set all intake clearances to .009" and all exhaust clearances to .011". I'm crossing my fingers that the next compression test comes out better than what I posted before. I'll find time to do that this week and record my findings.


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Old 10-07-2018, 09:35 AM
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I did mine last week, my figure was uniform 220 across all four. I did it cold, worried about removing plugs from a warm engine.
The 2nd round I accidentally cranked a few seconds more at cylinder 4 and get 245, did you crank it evenly?
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Old 10-07-2018, 10:30 AM
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Engine should be warm. I crank until the gauge stops increasing.
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Old 10-07-2018, 11:14 AM
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It will be interesting to see the next compression test results. I'll be surprised if the tight valves explain the compression test results. We shall see.
What did the plugs look like?
What kind of oil consumption do you see with the engine?

Last edited by rpg51; 10-07-2018 at 11:27 AM.
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Old 10-07-2018, 12:42 PM
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Originally Posted by rpg51 View Post
It will be interesting to see the next compression test results. I'll be surprised if the tight valves explain the compression test results. We shall see.
What did the plugs look like?
What kind of oil consumption do you see with the engine?
Plugs look fine, light brown in color. For oil consumption, it does use a little, but I haven't really kept track. I only get maybe 3,000 miles on the car each summer with a couple track days in there. It's always ran great for me. Crossing my fingers for more even compression numbers after this.
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