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Re: Leak down test results Posted by Justin VanAbrahams [Email] ![]() ![]() In Reply to: Re: Leak down test results, keith ![]() |
Boost on worn motors is fun, since any leak in the combustion chamber puts up to 15psi somewhere else - in the valve cover, crank case, PCV system, etc. If I had it handy, I would post a pic of how 20psi turned a dipstick tube into a Yosemite Sam-esque rifle barrel. ;)
There is really no predicting how an engine wears - sure, things wear out, but you can't anticipate what it will look like or when. Some motors croak at very early ages, others last forever with virtually no sign of age. There are too many variables (driving habits, maintenance, environment) to make it s worthwhile discussion.
What happens when you have cylinder leakage varies wildly - could be nothing noticeable, could be fluid consumption, loss of power, loss of economy, etc. But with the numbers you mentioned earlier, I would expect some significant idle quality issues if not drivability problems.
If you're confident you got the engine a TDC for each cylinder as you tested it, and those are the results, you have a tired old motor that needs a rebuild. One or two cylinders exceeding 20% is pretty bad, one approaching 40% is really bad.
posted by 12.195.130...
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