It's not an antique tractor................

Bob Bancroft · Oct 19, 2016

but it's on tracks! I recently purchased an ASV RC30 mini track loader. I went to drain the engine oil, and it wanted to glug out. I opened the oil fill, and it ran out fine. My first thought is plugged crankcase breather. BAD. But in checking it out, I found- the air intake goes right down through the valve cover. No intake manifold, unless it's built into the valve cover. There's a diaphragm which apparently allows crankcase gasses to escape into the intake, (all inside the valve cover) but closes and won't allow anything into the crankcase. Kind of a neat, simple arrangement. Which got me to thinking- my pickup and Jeep engines drain just fine, and aren't they supposed to be all tightened up so no crankcase gasses escape?

Mike M · Oct 19, 2016

Not sure why yours acts that way ? I have a few old JD's like an LA and M that don't like the oil being poured in unless you pull the dipstick out to let air escape. But they drain fine from what I remember ? Some stuff is just weird ?

Steve@Advance · Oct 19, 2016

Sounds like what they are doing is venting the crankcase into the intake so any blow-by gets reburned. That is good for keeping the engine clean and oil control, but bad for the crank seals. It tends to draw a slight vacuum in the crankcase, which causes the seals to run dry and draw in dirt.

That's similar to what the PCV valve does on a gas engine, sends crankcase gasses back through the intake to be burned. The newer engines are sealed better than the old ones. No place for the crankcase gases to escape, but it's not sealed. It is vented to the intake through the PCV or whatever means it uses to relieve crankcase pressure. When it's running all the incoming air is accounted for through the MAF (mass air flow) sensor, all the outgoing gasses are processed through the converter.

It's not an antique tractor................

Bob Bancroft

Well-known Member

Mike M

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Steve@Advance

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