Subject: [TR] Bad Engine Oil Leak

From: "John & Pat Donnelly" <[email-masked]>
Date: Wed, 22 May 2013 19:21:46 -0700

Listers,

I've been battling a bad engine oil leak on a TR4A for some time. The
undercarriage gets wet from the engine to the differential. After running
for 1/2 hr the back of the engine leaves a puddle of, maybe about 1/4 cup
worth, besides the half dozen others spots that occur underneath.  The oil
is now coming out of mostly the rear seal after plugging everything else.  I
had to remove the dipstick and plug the opening with felt because that would
push oil out. The distributor pedestal bubbles out little bits where the
tach cable attaches. The valve cover cap has oil coming out of the relief
hole. A few years ago it was small stuff. Now it's embarrassing. I believe
it's internal pressure doing it. 

The PVC valve is new (as was it's predecessor). The valve cover doesn't
leak. No leaks from the front engine mounting plate or the sump.

I've had the engine out 3X and .

1. Changed the rear seal to the Marx seal. 1st time I tore it by the
flywheel bolts, 2nd time verified it's intact  as evidenced through the 3rd
timed pulled.

2. Changed the piston rings. They're Deves, with openings rotated on thirds.

3. Redone the epoxy for the rear cam plug. Checked it on the third time
pulled. Perfect.

4. Checked all the rear oil galleys and they are clear, including those
going through the rear crank bearing housing.

So I decided this afternoon to do the compression and leak down tests. 

Compression as follows on a hot engine dry/wet (2 squirts)

1= 175/185  2 = 175/185  3 = 175/185  4 = 165/185

My  leak down test consistent of using a Harbor Fright leak down tester,
again on a hot engine. I used a stethoscope to check for sounds.

Every cylinder was consistent in % of leakage. The only difference was that
#1 had more air was leaking through the valve cover cap, but the % was
similar to the others. 

Checked the carb openings, they sounded consistent. Checked the dip stick.
Sounded consistent. No leaks in the radiator.

Maybe it's the HF Tester? The head has not had any work done to it in 15
years, I'm feeling it could it be the culprit? How do I tell?

Thanks!

Johnnie

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From: "John & Pat Donnelly" <[email-masked]>
Date: Fri, 31 May 2013 21:41:12 -0700

Here's a follow up to my findings. If you recall I had a bad oil leak on my
TR4A because of internal pressure.

What I found is that all PVC valves are not equal. I got a generic one from
O'Reily's. You know the one that "rattles"? Suck from the vacuum side and it
flows. Blow from the input side it doesn't.

The factory one is sporadic at best. It opens quickly and closes even
quicker. I have two of them and they both act the same. 

So I installed the generic and have driven it to work the last couple of
days. 15 miles each way. Not one drop of oil has leaked. Not one. I'm in
shock.

While I haven't played with it yet I believe that the factory version has
too strong a spring not allowing the vacuum to open the valve as needed to
relieve the pressure. Not sure if this is a lot issue or by design.

Anyway, I'm a happy camper with a LBC that doesn't leave it's mark.

Johnnie