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[craigbean]

I find a lot of oil on the valve cover from my oil filler cap after driving my '74 TR6.
Is there any reason why I can't put a rubber gasket on the cap?
Is this a symptom of oil pressure that's too high?
Does anyone else have this problem?

Thanks - Craig

[BobH]

Maybe check out your PCV system (such as it is...). 

Any pressure that is developed should be vented (via the nipple on the valve cover) to the carbs, or the charcoal canister, not out the filler cap.  Off the top of my head, I can't remember if the oil filler cap is 'sealed' with a gasket...Wait.  I think it is.  When I converted mine to fuel injection, (and lost the PCV connections to the carbs) I added an oil scavenger (between the manifold vacuum and the valve cover nipple), and I ended up pulling enough vacuum on the block that the dipstick was whistling, and you couldn't pry the oil fill cover off . 

FWIW, I just ran out and looked at my oil filler cap--there is a  'rubber' disc that would provide a sealing surface.  It's mounted oddly (not a flush piece of rubber just stuck in the cap-it's kinda spring mounted-maybe it relieves excess pressure/vacuum?).

Also, really excessive blowby could do this?  You could overwhelm the PCV system...

Anyone else?

BobH

[sullij]

I recall that the inside of my cap is a "fiberboard disc" I don't blow oil past it now; however, before I had the engine rebuilt and the venting corrected, it did.

[craigbean]

I finally realized the problem was too much pressure under the valve cover. Turns out the PO had completely screwed up the routing of the EGR tubing. I got that straightened out and now it's great. No more oil from under the cap.

[bill dye]

I am also experiencing "blow-by" from the oil cap (which is a vented, non-oem cap).  I have checked the breather hose exiting the valve cover and it is not restriced. The hose on my '73 TR6 goes into a T which has then has a short piece of 1/2" hose that connects to each carb. It appears that there is more pressure build up under the valve cover than breather hose can handle.  After a 30 minute engine run, I usually get at least a couple tablespoons of oil on top of the finned valve cover.  Have not figured out the cause yet.

Bill    

[craigbean]

Hi Bill -
I'm no expert, but for what it's worth, make sure you're hose routing is correct. Here's an interesting article I dug up when I was having this problem.  http://www.templeoftriumph.org/tsoa/TSOASep74.pdf
The carbs draw "vapors" from the valve cover and they are then sent through the charcoal canister, through the anti-run-on valve and then back to the manifold.
Also, make sure your charcoal cannister is working. I opened mine up and simply replaced the old charcoal with aquarium filter charcoal from a pet store. I also had to fabricate some new screens using materials I found at a hardware store. I tried to find screens that matched the old ones as closely as possible.
Good luck.
Craig

[bill dye]

Hi Craig and thanks for your response.  I have a TR mechanic looking at the engine next week be sure that everything is as it is supposed to be.

Thanks,

Bill