[TR] TR4 road draft tube plug

John & Pat Donnelly pdonnel1 at san.rr.com
Mon Sep 7 07:58:04 MDT 2015

I too had oil coming out from every nook and cranny. The rear main was leaking like a sieve. Blue smoke followed me everywhere. I had oil coming out of the dip stick! So I tried Marx's rear seal. Helped the rear main leaked. But was still there. I tore the engine apart twice. Chasing this oil leak problem was getting ridiculous. Grrrr.


So, what causes the oil leaks? Too much internal pressure (and assuming you can assemble an engine properly). If you remove the gulp valve the leaks go away. But that's not the design, so what if you go to another gulp valve? So I went to my local store and found a cheap inline PVC valve for $5. Works like a champ. I no longer see blue smoke, in fact there's no more leaks - at all. I spent hundreds of bucks when all it took was a little  $5 part. I feel like a fool for not thinking of this earlier.



'67 TR4A



From: Triumphs [mailto:triumphs-bounces at autox.team.net] On Behalf Of Brad Kahler
Sent: Monday, September 07, 2015 4:51 AM
To: Geo Hahn
Cc: Triumphs
Subject: Re: [TR] TR4 road draft tube plug


My objective is to track down and eliminate oil leaks.  I fix one oil leak and another one or two show up.


I've had oil leaking from the timing chain cover center stud, the bolts that mount the coil to the block were leaking, I always seem to have oil on the heads of the oil pan bolts and there might be oil coming from the rear main seal.  Also the timing cover seal was leaking as well.  The engine is new with maybe 1500 miles on it and was built by a well known Triumph engine builder.  The timing cover leak was fixed by adding a speedi-sleeve to the crank pulley.


Unfortunately I've not been impressed at all with the engine builders work.  When I first got the car (with new engine installed already) I couldn't get it to stop smoking.  After multiple head gasket swaps thinking it was coolant into the cylinders causing the smoking I finally realized after the third head gasket that each time I pulled the head to replace the gasket there was always about 4 tablespoons of oil sitting on top of each piston.  I was so focused on coolant being the problem that I totally missed what the oil on the pistons meant.  


Looking closer I realized the cylinder walls were bright and shiny with no cross hatching.  These were new 87mm liners and pistons that unfortunately were never finished honed.  I pulled the pistons, cross hatched the cylinder walls with a hone and that solved the smoking issue.  But the engine has always leaked oil from seemingly everywhere.  However no oil seems to flow out of the draft tube.  That may be a clue but I can't think of what it might be.


The car came with a TriumphTune cast valve cover but didn't have a manifold or carburetors.  So I installed a set of HS6s that were on the shelf.  I initially tried the original style of air filters with the port in the center and the flame trap.  The TriumphTune valve cover doesn't have a baffle at the breather port and I ended up with an excessive amount of oil going into the carburetors.  

I then swapped air filters to the larger oval shaped filters and installed one of Richard Good's PCV kits.  I still seemed to have some oil show up at the carburetors so I have now installed an original chromed valve cover.  This seems to have slowed down the oil going to the carburetors but the leaks elsewhere seemed to increase.  


Since I have all the parts on hand to try the gulp valve and vented valve cover cap I thought I would give that a try.  Yesterday I temporarily capped off the road draft tube but I'm still waiting on a replacement diaphragm for the gulp valve.  One of these days I'll do a leak down test and a compression test but I don't think the rings are the problem.  When I honed the cylinders I installed new Total Seal rings.



On Sun, Sep 6, 2015 at 12:24 PM, Geo Hahn <ahwahneetr at gmail.com> wrote:

Brad -


Just curious - what is your objective in trying this?


It may spare the environment some oil fumes as you drive and may or may not decrease the oil drip on your garage floor (may even increase it depending on engine condition).




On Sun, Sep 6, 2015 at 4:56 AM, Brad Kahler <bkahler1 at gmail.com> wrote:

Geo, I'm wondering if your definition of "easier" is the same as mine! :)


It's my understanding that the early TR4s were identical to the TR3, i.e. push-on valve cover breather and road draft tube.  The mid to late TR4s had the air filters with the tube in the center with a flame trap coming from the valve cover, no road draft tube and and the valve cover cap was a sealed type.  


The TR4As had a vented cap, gulp valve and no road draft tube.


I'm going to do some testing by installing the vented valve cover cap, installing the gulp valve and I've temporary capped the end of the road draft tube.  It will be a few days before I can test this setup as I'm still waiting for the replacement gulp valve diaphragm to arrive.




On Sun, Sep 6, 2015 at 12:30 AM, Geo Hahn <ahwahneetr at gmail.com> wrote:

I have done the opposite, removing the plug and installing a road draft tube on my late TR4.


If anything what you have in mind should be even easier, but...


I installed the tube because the small opening on the TR4 valve cover could simply not relieve enough crankcase pressure - oil was oozing from every pore.   Perhaps the TR4A system is more effective though.




On Sat, Sep 5, 2015 at 4:32 PM, Brad Kahler <bkahler1 at gmail.com> wrote:

I'm contemplating removing the road draft tube on my TR4 and am wondering if anyone has successfully removed the tube and installed the plug with the engine still in the car.  


It kinda looks like it would be a job for a contortionist!









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