 first compression test fails, second passes, can compression improve? |
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| siverson |
 Aug 11 2013, 12:16 AM
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#1
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Advanced Member  Group: Benefactors Posts: 2,458 Joined: 5-May 03 From: San Diego, CA Member No.: 654 Region Association: Southern California 
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Hi,
I'm looking at a -6 that had on compression test on 7/24 and the results were: 1-160 2-170 3-155 4-150 5-170 6-110 That car has sat for quite a while but the owner says it runs well. He asked the same shop to test the compression on 7/31 and now cyl #6 is showing 140. Can compression improve when taking a car out of storage and driving it? Or is this just sloppy work on the shop that did a PPI? -Steve |
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| PancakePorsche |
Aug 11 2013, 12:49 AM
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#2
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Member Group: Members Posts: 236 Joined: 29-July 11 From: Southern California Member No.: 13,373 Region Association: None |
Yes it can. rings could free up, valves seats can clear up, and more oil on pistons from cranking can increase pressure. valve clearances must be checked before performing compression test.
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| JoeSharp |
Aug 11 2013, 06:03 AM
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#3
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In Irvine, Ca. May 15-18 Group: Members Posts: 3,947 Joined: 9-July 03 From: DeLand, Florida Member No.: 898 Region Association: South East States |
(IMG:style_emoticons/default/agree.gif) Yeah Steve, what he said.
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| rgalla9146 |
Aug 11 2013, 06:11 AM
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#4
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Advanced Member Group: Members Posts: 4,743 Joined: 23-November 05 From: Paramus NJ Member No.: 5,176 Region Association: None
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QUOTE(Joe Sharp @ Aug 11 2013, 05:03 AM)  maybe forgot to hold the throttle open for # 6 ? |
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| siverson |
Aug 11 2013, 11:57 PM
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#5
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Advanced Member Group: Benefactors Posts: 2,458 Joined: 5-May 03 From: San Diego, CA Member No.: 654 Region Association: Southern California
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Got it, thanks.
-Steve |
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| Woody |
Aug 12 2013, 08:15 PM
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#6
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Sandbox Rabblerouser and head toilet scrubber Group: Members Posts: 3,858 Joined: 28-December 10 From: San Antonio Texas Member No.: 12,530 Region Association: Southwest Region |
Could have had a chunk of carbon holding a valve open.
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| scotty b |
Aug 12 2013, 08:24 PM
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#7
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rust free you say ? Group: Members Posts: 16,375 Joined: 7-January 05 From: richmond, Va. Member No.: 3,419 Region Association: None |
Once it runs again, it can improve even more as everything " re-seats " and As Woody said, a chunk of carbon, acorn shell, mighty mouse terd, chopstick, etc could have fallen into the chamber and kept a valve from closing fully.
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