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TR2/3/3A Plugged valve cover breather Cap?

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K

karls59tr

Obi Wan
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Anyone heard of a plugged breather cap causing oil pan leaks? I had replaced the oil pan gasket about a year ago and did all the prescribed metal straightening and gasket recommendations. After some time i noticed I was still getting some oil leaks. Realizing I had never thoroughly cleaned the breather cap I let the mesh soak in solvent and blew it out with compressed air. The leaking seems to have stopped! Is it possible that pressure was building up in the motor and forcing oil out where it shouldn't? Where does the "blow by" tube fit into this scenario?:confused:
 
The crankcase is supposed to ventilate as air from the fan is captured by the valve cover cap. The slight positive pressure from the fan forces a bit of air into the engine. Then, the draft tube on the lower left is designed to pull a slight negative pressure as the car moves, so the crankcase fumes are drawn out there.

If the cap was plugged, there is a good chance your draft tube is also plugged. I would think both would have to be restricted to cause the crankcase to build pressure and cause a leak. Of course bad rings can cause enough internal pressure to overwhelm the vents.
 
I had a similar experience recently at the TRA in Gettysburg. I had an aftermarket alloy valve cover fitted and apparently the tiny hole in the oil filler cap, which is on the rear of the head not the front, may not let this ventilation system function. I also had a new silicone gasket on the valve cover that had a one inch piece missing when I removed the valve cover. It was blowing oil out, into my battery box, so most of it drained out the battery box drain tube. Going back to stock valve cover and cork gasket to see if that helps.
 
Stevenry said:
wouldn’t under the valve cover be open to the crankcase and draft tube via the push rods?
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Yes. I checked my drat tube and it was perfectly clear. I'm still pondering why I had positive pressure under the valve cover. The engine only less than 5 K miles on it, so don't think a valve stem seal is leaking. I'm going back to the stock valve cover to eliminate the alloy cover as a variable in the analysis.
 
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