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Discussion Starter #1 (Edited)
I have had this happen 2 times in the past (could have been something else that caused this ) Anyone else every have this happen ...I have been in the trade for 10 years and came across this twice ...What would cause this ...Is this possible ...I know bad rings would but they both ran great ...bad vent it would smoke all the time ..Bad valve it wouldn't run or if it did it wouldn't run very well
 

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No! As you describe it , no it is not possible. You might be getting blow by through the crankcase ventilation system which usually vents into the air cleaner.
 

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Discussion Starter #3 (Edited)
No! As you describe it , no it is not possible. You might be getting blow by through the crankcase ventilation system which usually vents into the air cleaner.


I am not sure why as they both ran great ..I was told you could do a comp test this way and thats what i was doing when this happened both times one was a Honda over head valve the other was an 8hp T.C engine ...Got me stumped i thought it had something to do the suction on the intake stroke ....
 

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I dunno. The only thing bad that I can think of might be valve/piston interference due to reversing rotation if that clearance is normally very close. Otherwise it should act like it was going the right direction as far as blowby is concerned. If there is an oil pump, it should be drawing from the galleries and dumping into the sump. Not good for starting it later, but not all that bad either on a small engine.

I assume you are not using the starter for this exercise? Using something else makes me think you're turning it too fast, but that still doesn't explain the oil, just bent valves.

I don't understand how you can get an accurate compression test by reversing rotation. The valve timing is critical for cylinder fill and reversing throws the valve timing out the window. The clearances dictate that.

Just my WAG.

Bob :rauch10:
 
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