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Leak down results
I just replaced the bushings on my throttle bodies, did a valve adjustment and a tune up and thought I would do a leak down test also. The results surprised me.
My car is a 1971E with 140,000 mostly freeway miles and still has original motor....not rebuilt. I bought it in 1978 with 101,000. Results: 4 cylinders had 0% leakage and 2 had 1%. The 2 with 1% had air noise coming from the oil filler. To make sure the tester was working properly I turned the crank after 3 minutes and the air poured into the cylinder. Are these common results on a car with this mileage? I was expecting at least 20% leakage or more. Thanks for any input, Mark  
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Mark 1971 911E targa Priors: 1955 Speedster, 74 911 coupe, 69 911T coupe, 74 911 slant nose w/928 lights, 03 911 Turbo |
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05-02-2021, 05:14 PM
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Functionista
Join Date: Jul 2011
Location: CO
Posts: 7,717
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I leak these cars at the job regularly and can say that your findings are not unreasonable on an engine that has seen regular oil changes/maintenance etc. Avoiding high temps/overheating also makes a difference. My own car had comparable readings and it’s a well used on road and track, so much so I questioned my equipment.
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Jeff 74 911, #3 I do not disbelieve in anything. I start from the premise that everything is true until proved false. Everything is possible. |
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05-02-2021, 05:36 PM
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Registered
Join Date: Mar 2019
Posts: 1,634
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Set the inlet pressure to 100 psi and recalibrate to zero before plugging into the cylinder.
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05-02-2021, 05:48 PM
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Functionista
Join Date: Jul 2011
Location: CO
Posts: 7,717
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^^ Also true, always use calibrated gauge and set to 100.
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Jeff 74 911, #3 I do not disbelieve in anything. I start from the premise that everything is true until proved false. Everything is possible. |
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05-02-2021, 06:44 PM
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