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» Northern California Ford Owners     » Automotive   » Tech Talk   » 03 cobra low compression need advice

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Author Topic: 03 cobra low compression need advice
Mr.10psi
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Member # 11062

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Hey guys, im looking at buying an 03 cobra that had a compression test done and the results were 146psi across the board with one cylinder being i believe 141psi. Basically 7 cylinders were the same except the last one. When i heard this, the first thing i thought was that this is low and the motor must be tired even though the car only has 25k miles on it. Before i forget to mention, he did the compression test on a cold morning. Motor hadnt been fired at all that morning before the test. Any advice is appreciated. 5307748968 if you guys want to text me what you think or just reply here.

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02 white saleen(sold) 347 stroker in the works

Posts: 1337 | From: 530 | Registered: Jul 2011  |  :
Martinna
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5 psi off doesn't sound like much. Test that cylinder again and retest a 146 psi one. Lots of things can cause one cylinder to be low. A worn O ring. The adapter not fully tightened. Battery getting low. Inconstant number of cranks between cylinders. If all this checks out, put a tea spoon of motor oil in the cylinder. If it boosts the number, the rings could be worn.
Posts: 1093 | From: City | Registered: Oct 2012  |  :
SLOWSN95
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That doesn't seem bad. It is an 8.5 to 1 motor.

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94' GT
347 Stroker
MM Suspended

2003 SB SVT Lightning
Pullied and Lowered

89'Hatch-SOLD

Posts: 2214 | From: 510/east bay | Registered: Mar 2008  |  :
JohnB
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Member # 969

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I wouldn't put a lot of faith into a compression test. You really need to perform a leakdown test to see what's going on.

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1965 Shelby Cobra
1993 Cobra
2012 F150 Raptor
2020 GT500

Posts: 6523 | From: Orlando FL/Redding CA | Registered: Mar 2002  |  :


 
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