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MG TD TF 1500 - Rear Main Oil Leak Limit

Gents, What is roughly the upper limit on how much oil might come out of the cotter key in the bottom of the bellhousing and still be acceptable? I read the archives and the range is from almost none to quite a lot in some cases. Mine is about a drop every 1-2 seconds hot and running, which adds up. I'll need to make one of those nifty oil collectors as seen in the archives. Mine will decrease as soon as I up the oil viscosity after a little more break-in and an oil change. The collectors look like they would hold a half pint or more! I'm willing to pull the whole works out over next winter to fix the thing, so I'm not too discouraged by this...just a little disappointed. I don't think it's the cam plug, but I guess that could be the case. It did not leak on the test stand...oh, well. Mike
MW Davis

Mike - "...just a little disappointed."

Look at it this way, You'll always be able to find your way home without having to go to the expense of purchasing one of those fancy GPS dodads ;-) Cheers - Dave
David DuBois

I've seen some cars hemorrhage a constant stream of oil, and others only weep a little it. My cars will drip a few drops from the size of a dime to a quarter after the engine is nice and warm and then turned off. I consider this the benchmark of success.
The oil in the "corkscrew" will drip out once the engines turned off and the crank eases to turn.
-David
D. Sander

Yes, Dave, I can just "connect the dots" on the road and I don't need a fancy GPS. Kind of like leaving crumbs behind. I love your sense of humor! Thanks!
MW Davis

I park over a kitty litter pan in my garage. I'm guessing 4 ounces a season (6 months).
Peter Dahlquist

It is said that cutting the rear main cap pipe to one inch solves the greater part of the leaks. In doing so it won't siphon the oil back up the pipe as the engine cools (most of this kind of oil leaks happen than). Look at http://www.geocities.com/jcurtoinc/ for details.

Not a big deal: just remove the carter pan, cut the pipe and re-install the carter pan.

See the archives for more info on this subject.

Jasper

JL Nederhoed

Jasper,
Look at http://www.geocities.com/jcurtoinc/ for details.

That link is not working.
Mort
Mort 50TD (1851) Mobius

I am going to speak up as a member of the "don't cut the rear main cap pipe" club. I succumbed to this armchair engineering theory while I had the oil pan off, and it actually seemed to make a minor leak worse. I am sure that numerous people are convinced that cutting the pipe is helpful - I am glad that it makes them feel good.
I wouldn't bother cutting it off, actually plan to return mine to the original design by the automotive engineers when I next have the pan off.
This pipe is not unique to these engines, it was a standard practice.
It would be worthwhile to check that the pipe is not plugged with sludge.

FWIW
Dallas Congleton

Some high quality aluminum drip pans are still available from Joe McGinnis, at $48....email me if you are interested. Doesn't solve the disease, but takes care of the symptom..and your friends won't be mad at you for dripping in their driveways....
Once you slow down the drip , you will still want one.(unless you are able to completely stop it, which may or may not be the result of your efforts).
Edward
E.B. Wesson

Perhaps cutting the pipe could help with shutdown drip, but would have no effect on a drip while running? If you do get into the motor again, remember to check the rear main oil galley plug as well.
George Butz

Mike,
This is the drip pan Ed is referring to. (After I painted it.)
Mort


Mort 50TD (1851) Mobius

That is a nice drip pan. My sump has ribs on it, however, and that might be an issue, but I can't tell from this right now. I will drop Ed a note.
MW Davis

Are you going to do Glenwood next week Mike?
LaVerne

While I have no practical experience cutting/not cutting the pipe, it certainly is not siphon action that draws oil up the pipe after shut down as a siphon must have the outlet lower than the inlet to work.
JE Carroll

Cutting the pipe is supposed to allow the oil to drain faster, as it no longer has the "resistance" of pushing down into the oil already in the sump. Upon shutdown, this would reduce the amount that fills up the rear cavity inside the cap, and therefore reduce how much will drain out. Some people swear it makes a huge difference and others argue it makes none at all. I suspect they are both right since every engine seems to act a bit differently, especially in regards to the amount of wear and alignment of the rear scroll.

I'm also in the camp of leaving things as the engineers designed them, unless substantial evidence is shown that an improvement will be made. But even so, I can't imagine how cutting the pipe could make the leak worse. It's more likely that upon reassembly, the new seals were not placed as well as the previous time.

As far as a "limit" goes, there isn't really one so long as you aren't running the engine low on oil during drives. The only real problem with leaking a lot is the mess it makes, the wasted oil, and the hassle of constantly topping it up. I knew a guy once who put a catch can under the rear of the engine, and when it was full he would pour it back in the engine. I don't recommend this but it shows how much oil can leak without hurting anything!
Steve S

The oil pipe could conceivably help by creating a downward suction, or siphon action by gravity flow on the oil in the cavity in the rear bearing, as long as it were full. Having the end immersed in the oil in the pan would keep a seal- if this is theory is actually effective.
Cutting the oil pipe could defeat this, or whatever means the pipe were effective, and allow the oil to accumulate in the rear bearing housing, allow more flooding of the rear oil thrower, and leak more at the rear gaskets.

I can apply some logic to this explanation, but I cannot follow the "upward siphon as the engine cools" theory.

I have also heard theories about short pipes, or even removed pipes, dumping the oil and it flowing back along the underside of the bearing housing creating a flood condition on the lower rear sump gasket.

FWIW
Dallas
Dallas Congleton

This thread was discussed between 31/05/2012 and 01/06/2012

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.