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Registered
Join Date: Oct 2002
Location: West Coast Canada
Posts: 75
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Compression Results - Questions
I have the compression test results from a Euro Spec '86 Carrera back, and have some questions. The results are 180, 180, 180, 175, 200, 200. As a Euro spec car, with about 50K miles, the 200 are OK. What concerns me is that 175 is outside the normal 10% rule..... I really do not want to get into engine work, especially with such low mileage.
What are your thoughts? |
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04-20-2003, 12:02 PM
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Join Date: Mar 2001
Location: Marysville Wa.
Posts: 22,431
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a small difference between compression numbers can be a large difference if you do a leakdown test. if you get a high leakage result on any cylinder, put the plugs back in and run the engine again to blow out any potential carbon bits from between the valve and seat, and re-do the leak test. 4% is pretty damn good. over 10% kind of makes you wonder. 20% and more, something's definitely not sealing well.
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04-20-2003, 12:17 PM
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Senior Member
Join Date: Jun 2000
Location: N. Phoenix AZ USA
Posts: 28,943
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Just ran the compressions on my 85 3.2 motor. Every one was between 160 and 165 and the motor has 93k on it.
While your readings are within a small percentage, the closer the readings are, the better condition the motor is inside and smoother the motor will run. JoeA
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2013 Jag XF, 2002 Dodge Ram 2500 Cummins (the workhorse), 1992 Jaguar XJ S-3 V-12 VDP (one of only 100 examples made), 1969 Jaguar XJ (been in the family since new), 1985 911 Targa backdated to 1973 RS specs with a 3.6 shoehorned in the back, 1959 Austin Healey Sprite (former SCCA H-Prod), 1995 BMW R1100RSL, 1971 & '72 BMW R75/5 "Toaster," Ural Tourist w/sidecar, 1949 Aeronca Sedan / QB |
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04-20-2003, 01:03 PM
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Join Date: Dec 2001
Location: MA USA
Posts: 2,938
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How does your motor run? Does it burn oil? If not and it runs good, I would drive it
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Dean 911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno, |
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04-20-2003, 04:44 PM
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Join Date: Oct 2002
Location: West Coast Canada
Posts: 75
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John, thanks for the reply. It was a PPI and I did not get the leak down done. Blown, it does not blow smoke on start up, but I do not know how much oil it burns (miles/qt).
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04-20-2003, 10:44 PM
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Senior Member
Join Date: Nov 2000
Location: Great NorthWest
Posts: 3,941
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What was the condition of the spark plugs when they were pulled out? Any of them carbonized or otherwise?
John
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'78 Targa in Minerva Blue |
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04-21-2003, 05:22 AM
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Join Date: Oct 2002
Location: West Coast Canada
Posts: 75
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John, the plugs looked OK.
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04-21-2003, 07:05 AM
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