[TR] TR4 road draft tube plug

Brad Kahler bkahler1 at gmail.com
Mon Sep 7 05:50:59 MDT 2015

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).
> Geo
> 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.
>> Brad
>> 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.
>>> Geo
>>> 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!
>>>> Thanks!
>>>> Brad
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