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Blowby
- Thread starter davjac889
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TR3driver
Great Pumpkin - R.I.P
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Some is normal. Lots is a sign of excess blowby, likely worn rings (but perhaps broken rings, damaged cylinder wall, etc.)
A compression or leak down test will give you a better idea of whether you have a problem or not. That said, if it runs OK, just drive it. They will run well enough even in fairly advanced states of wear.
A compression or leak down test will give you a better idea of whether you have a problem or not. That said, if it runs OK, just drive it. They will run well enough even in fairly advanced states of wear.
Geo Hahn
Yoda
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It is difficult to quote a particular number due to variations in gauges as well as engines -- so I mainly look for a reasonable number well above 100 and more particularly not a big difference among the cylinders (say not more than 5% or so).
The leak down test Randall mentioned is also very useful as it tells you where any compression loss is going. Harbor Freight sells a tester though there are many places on the web with instructions for making your own. I use the HF version but it works at fairly low pressure so a DIY one may be more effective as when you are listening & feeling for leaks a higher pressure might help.
10 OR 10.5 TO 1 Compression runs about 180, so a normal engine should be below that in the 150 range. But as others have said what you want to see is little to no difference between cylinders. There are other things to look for when evaluating the health of the engine such as oil pressure hot at idle as well as 3000+ rpm, what temperature does the car run at when driving at moderate speeds and at heavy throttle. Can you cool it down as your drive or does it continue to climb. How much oil does it use in 500 miles. These engines are very reliable and with a little attention will run for a long time.