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MG MGA - Exhaust from Rocker Cover

I never really checked this before, but today I had the A running and put my hand over the rocker cover vent. Definite rythmic puffs of air pressure coming out (no smoke, just air pressure.) Is this normal?
Steven B

Steve,
When the engine is running, the pistons are pumping air inside the crankcase. You will get some feeling of this over the vent, as you have. If the rings are worn excessively, exhaust gas will also go into the crankcase, and you will see that in the vent.
Mike Parker

Thanks Mike -
I'd think the "puffing" I am feeling from the top side would be more likely from the vent on the crank case side cover. I think Barney wrote about CC ventilation, I will dig up the archives and see what he said.
Steve
Steven B

Barney tells how the CC ventilation works at the bottom of this page. http://www.mgaguru.com/mgtech/engine/cv101.htm

When the car is not moving you would basically get the same "puffing" from both the valve cover and the tappet cover vents since there is no air seal between them. When the car is moving, air blowing over the pipe from the tappet cover creates a vacuum pulling gasses out of the crankcase, and sucking fresh air in through the hose from the valve cover.
Jeff Schultz

This thread was discussed between 16/07/2007 and 17/07/2007

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This thread is from the archive. The Live MG MGA BBS is active now.