I'm interested in oil leaks these days so I'll ramble on a bit in the hope
that I can help.
Where exactly does the oil leak from? Many TR-6s have external
supplementary oil feed lines that run from the back left side of the
cylinder head to a fitting near the oil pressure switch. These are usually
attached to the cylinder with a banjo fitting and sealed with copper crush
washers. Once you loosen the fitting at the cylinder head you have to
replace the crush washers or it will leak sooner or later.
You mentioned replacing the head gasket. Did you replace it with a modern
teflon coated gasket (Payen makes these) or one of the original style
composite gaskets? I've had excellent results with the Payen gasket (don't
use any sealent on these). I once had a nasty leak when I used a
reproduction composite gasket, but it was a WATER leak, not an oil leak.
Dumb question, but did you also replace the valve cover gasket? Some
aftermarket valve covers do not have a groove to keep the gasket in place
so I would check to see if you have one of these. If the previous owner put
webers on then the valve cover may have been changed as well. The original
cork valve cover gaskets do not seal well if you have such a valve cover
(some say they don't seal well either way).
When reinstalling my (aftermarket) valve cover I use a gasket maker product
called "The Right Stuff" which is made by Loctite/Permatex. I clean both
mating surfaces with a scraper and some lacquer thinner and then run a bead
of this black rubber/caulk stuff around the edge of the valve cover. Once
I bolt the valve cover back on I can drive away in 5 minutes- you do NOT
have to wait for this stuff to cure like some other products. At $13 a can
it isn't cheap, but it works extremely well and one can makes more than two
TR-6 valve cover gaskets. Don't let the cutesy name stop you from trying
this stuff- you'll like it.
If you have a pressurized crankcase oil will eventually leak out from
somewhere. I've had it leak from the oil filler cap (check the gasket and
seal up any weep holes you see with silicone) and the studs which secure
the valve cover to the head (I now use fiber sealing washers and deep cap
nuts to attach my valve cover).
PCV valves run a delicate balance- they will only open with the right
amount of manifold vacuum. They aren't supposed to open at idle OR at wide
open throttle. If the PCV valve you selected isn't opening because it is
calibrated for some other engine then it isn't going to relieve the
pressure in your crankcase. If you ran your engine "plugged" for a while
then the pressure just built up until it found a way out.
Cheers,
-Erik
At 02:01 PM 9/14/2000 -0400, Wendy Hart wrote:
>
>When we bought our '75 TR6, the only breathing tube left in the car was a
>hose going from the stock valve cover to an old Castrol oil bottle residing
>where the charcoal canister belonged. Once we got the car running somewhat
>reliably, we found that the head gasket was weeping in a 3" length along the
>drivers' left side of the motor.
>
>We replaced the head gasket this past spring and also put the ARP head studs
>in, hoping to eliminate the problem (the car has a 10:1 CR). Nope, didn't
>fix it. The sucker still leaked.
>
>Our next theory was that the engine is designed to run under vacuum
>conditions, something we lacked because of our oil can breather. If we could
>hook the valve cover to the carbs (dual Weber downies) or the manifold, that
>would release the pressure forcing the oil out and cure the leak. So, this
>past weekend, Al (my hubby) attached one end of a hose to the valve cover
>and the other to a PCV valve. The PCV valve then went to the manifold's
>banjo connector for the brake servo. What the heck, see what happens, right?
>
>Sunday was an autocross approx. 45 minutes south of us. We hooked up our
>shiny, new, just-finished-building autocross trailer to the back of the TR6
>with its shiny, new, just-finished-building hitch and were on our way.
>
>"Honey, do you smell oil burning?"
>
>"Yeah, and look, our oil pressure is going down!"
>
>"Maybe we should pull over..."
>
>We got to the next rest area and sure enough, the engine was covered in oil.
>So was the entire underside of the car and most of our shiny, new (now
>slick) trailer. Of course, we had a spare quart of oil for such an
>emergency, so we put that in and headed for the next exit to turn around and
>go home.
>
>We had to buy another quart to put in at that exit. That put us back in the
>safe zone and we limped back home. When we parked it in the garage, the poor
>thing had oil dripping off of the entire underside, even the tailpipes. I'm
>not looking forward to getting all that stuff cleaned off the car!
>
>What caused it? The car has been leaking, but never enough to lose oil
>pressure, even when running hard at autocrosses. We're not sure why. It's
>possible that having the PCV hooked up to the manifold and the car under
>load (pulling the trailer) affected the pressures inside the engine enough
>to really let the oil flow. Maybe the head gasket finally gave in
>completely. This weekend's test is to put the oil bottle system back in and
>take the car/trailer out onto the highway and see if it happens again.
>
>We'll let you know...
>
>Wendy Hart
>1975 TR6
>1976 TR7
>
>
>
>
>----- Original Message -----
>From: "Paul J. Burr" <tigerpb@ids.net>
>To: "Triumphs (E-mail)" <triumphs@autox.team.net>
>Sent: Wednesday, September 13, 2000 9:50 PM
>Subject: Weber downdrafts and TR6 PCV system
>
>
>>
>> OK Gang, here's the dilemma.
>> My newly acquired '74 TR6 was outfitted by the previous owner with the
>dual
>> Weber down draft carbs and a nice alloy valve cover. So far so good. But,
>he
>> completely eliminated the PCV system, which makes for to much pressure
>under
>> the valve cover. This in turn makes the oil want to seep out under the oil
>> filler cap.
>> Any of you folks run into this problem?
>> My first choice would be a vented and filtered oil filler cap. But, the
>> alloy valve cover has as a 2" I.D. hole in the cap. A quick check of the
>> parts catalog shows the biggest cap of this type is @ 1 3/4".
>> Anyone have a source for these oversize filler caps?
>> My next plan of attack would be to cast my vanity aside and remove the
>fancy
>> cast valve cover for the stock one sitting on my work bench. I can then
>fit
>> a vented cap. Next, I could fit a PVC valve to the vent hose on the valve
>> cover.
>> My next problem is where to plumb the opposite end of the PCV valve.
>> Should I fit it to the it to the manifold? Or, should I use a "T" fitting
>> and plumb it into the base of each air cleaner?
>> Any suggestions would be welcomed.
>> Paul Burr
>>
>
--
Erik Quackenbush, V.P. Operations, Midwest Filter Corporation
1-847-680-0566 fax: 1-847-680-0832 http://www.midwestfilter.com
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