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TR 3 crankcase venting.

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bfitz

bfitz

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I bought an aluminum valve cover for my TR. It does not have any sort of vent for air intake. Now, is the road draft tube enough or should I adapt a breather to the valve cover? Anybody try this? How about plugging the road tube, fitting a breather into the valve cover and running a PCV system using a valve from a 4 cyl of comparable displacement?
Has anyone fitted a filter over the end of the road tube to keep dirt out, or is that a non issue?
 
On the original road draft system used a vented oil filler cap in the valve cover. And you could put a screen on the tube, but it's more likley for the screen to plug up, than it is for dirt to ever get in. I would just leave it alone.
If you want to run a PCV system you can get a plug for the draft tube hole in the block. They were fitted to TR4As Moss part # 319-005.
But then you need a breather pipe, and a PCV vlave setup. Also check out later TR4A s for that.
Personally I'd just keep the road draft tube. It's correct, and reliable (maybe not very environmentally correct) mot to mention easier.
If your new valve cover has a sealed oil filler cap and a pipe sticking out the side, just fit a small filter to that pipe for a breather.
 
that's the problem; no vent in the valve cover, and the filler cap on it is not vented.....TR 4 system just sounds like trouble...anybody make a vented cap? I may just adapt a K & N breather to it
 
Cuious, Fitz, this aftermarket (cast?) aluminum valve cover has no holes in it? Where does the "road tube" fit? The expression "to breathe" for a valve cover really means "to exhale" in that you want negative pressure on the crank so as not to blow gaskets. Haven't owned a side curtain TR for over 30 years so have forgotten the setup, but my 6 has the pressure on the aluminum valve cover sucked out via the carbs thru an (aftermarket) oil separator. Doesn't the crank on the 4-banger have a vent? Forgotten. The purpose of the road tube is usually to create a negative pressure at speed, when the pressure in the crank is it's highest, with the suction effect of fast-moving air creating a vacumn. Or am I all wet, as I have been known to be before.
Can't you drill and tap the cover?

Bill
 
As Banjo has mentioned, if you use the road draft tube, you will need to somehow vent the valve cover. The original oil filler cap is vented.

That said, the road draft tube system is not very efficient at venting the crankcase. Personally, I'd opt for a PCV system. To be quite frank with you, a correctly operating Positive Crankcase Ventilation system is not a detrement to your engine, but rather, it is good for the motor. It will keep the internals cleaner, you will have less blow by because of pressure build-up. It sucks out the unwanted gases that seem to get by the rings. The oil stays cleaner. Engines run better with some vacuum in the crankcase, rather then pressure. You will also have less oil leaks. Your engine will thank you for it.
 
I would certainly keep the crankcase breather tube... in fact, I added one to my TR4.

The ventilation on the TR4s was pretty crude. No PCV valve, just a small tube from the valve cover to the carbs with everything else sealed up tight. Oil was oozing from every pore until I put on a draft tube. Now, though not leak free, it leaks very little and oil consumption is negligible.

I would think that if you are not seeing oil pushing out around the valve cover cap or gasket than it is not a problem. Else... all the cast aluminum covers in the Moss catalog appear to have a side tube for venting and this could be added to yours fairly easily.
 
TR6 BIll-yes my valve cover is cast aluminum, no vent in the cap or body..the road draft tube fits into the block near the bottom of the engine on the driver side.
sounds like a PCV system is the way to go, with an intake filter for incoming air. [K&N valve cover breather].
I don't like the idea of the road draft tube, but maybe I'll clamp a small K & N to it, to keep the rocks out, and run a TR4 ish system to the carb air filters.
TR6Bill-where did you get that aftermarket oil seperator?
Thanks for the help guys...
 
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TR6Bill-where did you get that aftermarket oil seperator?


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goodparts.com

Bill
 
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...I don't like the idea of the road draft tube, but maybe I'll clamp a small K & N to it, to keep the rocks out...

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Unlikely that anything could go up that tube. In addition to the double bend outside the engine their is a convoluted route for vapors to escape the block... by no means does the top end of the tube open directly into the crankcase.

A filter will probably do no harm but I would be wary of messing too much with that tube. A junior mechanic decided to fool with the one on Ken Richardson's TR2 just prior to the Jabbeke run (to get it well clear of the underbody shield) and as a result it sucked much of the oil out of the engine and nearly ruined the day for everyone.
 
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