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Noah930 Noah930 is offline
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Join Date: May 2005
Location: Los Angeles
Posts: 13,851
I've never done it myself, but you need a compression tester (looks like a gauge you hook up to a sparkplug hole). Engine is supposed to be warm when doing the test. Leakdown is not just whatever numbers you calculate, but also it makes a difference from where you hear the leaking.

When I had my PPI, they obtained both numbers. I have no idea what the "factory specs" are supposed to be. I've never seen them printed anywhere. Has anyone else? So I just went with the fact that the numbers were all clustered together. (Maybe that just means the engine is entirely worn out in all 6 cylinders?) On Pelican, I've seen people post numbers in the 110-120 range, and others in the 160 range for turbo motors.

For leakdown, the lower the better. Again, clustering of the values together is a good thing. Some guys have posted values of 3 or 4%. I think mine were closer to 10-12%; I realize those figures seem very high, but that was 20K miles ago and the car still scoots, so who knows...
1987 Venetian Blue (really looks like grey) 930 Coupe
Old 06-18-2010, 08:56 PM
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