# JD 2640 pipe that feeds into the heads smoking a little



## jsh2010x (Aug 1, 2019)

Hi, I'm new to this site so please bear with me. I've a JD2640, It starts and runs fine, no smoke from the stack ever. But on the "driver" side there is a pipe coming down from the heads, when it gets really hot and doing hard work it blows a little smoke. Not white, a tinge of gray. Water is good, oil is good. Any idears? I'm thinking a clogged radiator or something. Thanks in advance.


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## pettibone (Jul 18, 2015)

Sounds like a little blowby to me, nothing to get to excited about, as long as there's no water dripping out with it.


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## Tx Jim (Jun 30, 2014)

Ditto


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## rjmoses (Apr 4, 2010)

I guessing by the little pipe, you're talking about a pipe that comes off the valve cover and runs down below the bottom of the engine and is open on the bottom side?

If so, that is the crankcase breather tube (port) which allows blow-by gases to vent from the crankcase. There is always a little vapor that gets past the piston rings and into the crankcase. Most engines nowadays recirculate that gas into the intake manifold and re-burn it.

It's usually no big deal, especially when the engine is working hard. Watch the guys doing tractor pulling and you'll see a lot of gas coming from under the engine. They're running high compression and lots of fuel so lots of blow-by.

Hope this helps.

Ralph


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