When is Blow By too much?

[jlongjohn]

Seen lots of opinions in searches, wondering if anyone has a good method or line of thinking on when blow by is too much and rings should be replaced? I have an L35 with ~2k hours and I am debating. Also has anyone done a rebuild on the L35 motor? Any help is appreciated.


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[100 td]

Personal preference, 2000 hrs is minimal in my book. If it's not significantly down on power and not choking you while using it, and you don't have to add a gallon of oil between changes, I wouldn't be worrying about it. YMMV

 

[North Idaho Wolfman]

Blow-by is Blow-by
If you want a real answers of if you should rebuild it, you should do a compression test.

 

[jlongjohn]

Thank you, I agree on the hours and good idea on compression test. I just bought the machine so I am just checking everything out, definitely has some blow by but seems to run ok. I only have 2 hours on it since purchase so I don't know yet if it uses oil. I do have some "fog" coming from the one vent line.


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[Thorny]

ring replacement timeframe can't be measured solely by operating hours. If your motor sucked some silt past the air filter it's going to wear faster than one that didn't. If the steel used to make your rings was on the soft side it could wear faster. If the crosshatch on your cylinder was too deep your rings could wear faster.

Compression is another indicator, but the pressure loss could be at the rings or at the valves.

To measure ring wear you've got to measure end gap, but by the time you've torn into the motor that far, just replace the rings. At least that's how I do it.