Dennis,
I had a small leak where the steel crankcase vent tube exits the
side of the dipstick housing. Found that with the balloon pressure/soap
bubble test and fixed it with JB Weld. I have a premolded “S”
shape automotive antifreeze hose that runs from the dipstick housing thru the
rear baffling that tests OK under pressure and vacuum. I was running a
Andair air/oil separator with the drain to a 3 oz reservoir to allow measuring
of blowby between oil changes. It was masking the blowby that I think
started at about 30 tach hours by filling the reservoir and then the bottom of
the air/oil separator before large quantities came out the vent tube. I
removed the separator early in testing to see if it had anything to do with the
problem, it didn’t.
Steve
Did you install the Andair air/oil separator you
bought? Does it fill with oil immediately?
Your engine was rebuilt at the same place as mine. The
crankcase vent fitting just below the oil filler cap on mine nearly dead-ends
into one of the intake air runners. When I tried to run the conventional
black rubber vent hose from that fitting, it kinked from the tight bend.
I'm sure you would have noticed it kinked if that were the case on yours, but I
thought I'd mention it just in case. (By the way, I solved the
problem by using silicone hose from Spruce, part number
05-00671. The silicone hose bends tighter without kinking than the rubber
hose.)
Anyone have a theory why the manometer pressure in the
crankcase vent line spikes up (I assume it's reading pressure, not vacuum) when
you reduce power in the traffic pattern? I would expect the pressure to
drop, not increase. But there's a lot I don't know about engines.
Is it because the piston rings momentarily lose their seal against the cylinder walls with
the drop of pressure on top of the pistons, allowing blowby?
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