Mysterious hole in transmission

[Member 10617]

I think I have found the source of one of my oil leaks. Here is a photo of the underside of my transmission. As you can see, there is a hole that is dripping oil. I assume the oil drips as I drive. When I stop and park the car, it leaks for a moment and then stops.

Can anyone explain what this is? Is it missing some sort of plug?

Thanks

 

[Darrell_Walker]

The hole is there to let the leaking oil drain out

Could be a leak from the front seal on the transmission, or a leak from the rear main seal, or from the camshaft plug.

Can you tell if it is engine oil or gear oil?

 

[TR3driver]

That is just a drain hole for the bellhousing. It is not supposed to be plugged. If the leak is gear oil, then most likely the front seal on the gearbox is leaking.

But more likely it's motor oil, and you are seeing the infamous rear main seal leak.

 

[Geo Hahn]

That is the hole at the bottom of the bellhousing? I think that is engine oil from the rear seal.

Some cars (Healeys?) have a loose cotter pin (split pin) in there -- the idea is that the pin blocks the hole when the car is parked but shakes and lets oil drip out when you're driving along. Crude but effective.

 

[Deleted member 8987]

Actually, the cotter key has been used on other marques, too, for a long, long time, and what it does is rattle a bit whilst driving, and it keeps road dirt from plugging the hole, filling the bell housing enough to catch the ring gear, and soaking the clutch disc.

 

[Member 10617]

Looks like engine oil to me. so it must be the rear main seal leak.

How important is this? Is is something I need to have fixed soon, or can I live with it for the time being without harming the car (checking the levels periodically, of course)?

 

[Darrell_Walker]

But more likely it's motor oil, and you are seeing the infamous rear main seal leak.

And if it was the sump bolts at the back that had oil on the heads, that is probably where it came from.

 

[Member 10617]

The sump bolts are now dry, free from oil. The oil seems to be coming from that little drain hole.

 

[Deleted member 8987]

This is part of the curse of LBC's. Fix one oil leak, it WILL find it's way out somewhere else.

 

[Member 10617]

Ha, ha. Yes, you are right. I said the same thing just today... but used a little stronger language...

I'm "OK" with some oil leaks, but I'm too much of a novice to know if there is a serious problem or just an aggravation that requires checking the levels from time to time.

If something "needs" to be fixed, I'll have it fixed. But if it doesn't "need" to be fixed, I'll live with it (reluctantly).

 

[Geo Hahn]

Looks like engine oil to me... can I live with it for the time being...

I've been living with it since Nixon was in the White House. A small amount of oil can make a large spot whilst having no perceptible effect on the oil level in the engine.

 

[TR3driver]

Not a problem if you want to leave it, Ed. Just be sure to add some oil when the engine gets more than a quart down.

Although in theory it is possible to change the rear main seal without pulling the engine (and front apron), you still have to pull the gearbox, clutch & flywheel, then work with the engine hanging over your head. Mine is definitely going to wait until I have the engine out for other reasons!

 

[Member 10617]

Thanks for the reassurance, George. I'm not sure what a "small amount of oil" is however. I'd say that when I park the car in the garage, a tablespoon of oil leaks out. What has come out while driving, I don't know....

How does that sound to you?

I've also noticed that I need to top off the transmission with about a cup of oil every -- say -- 500 miles or so. The engine oil level doesn't change much at all.

My problem is that I'm entirely in the dark on these matters. Just see oil and think .... "problem"

 

[poolboy]

My problem is that I'm entirely in the dark on these matters. Just see oil and think .... "problem"

If this were a modern car you might have reason to be concerned, but this is a 50 year old car. Back in the day Chevys and Fords dripped oil in the drive way too.. Don't judge the antique car by modern standards. Adjust your frame of reference and just admire the way it looks and drives. Forget about it's table manners.

 

[Member 10617]

Hi, Poolboy,

Good advice... My only concern is that I don't do damage to the car by not having this fixed. If the leaks are not consequential, then I'm willing to accept them. Newspaper on the floor takes care of the outward signs of the probme.

As for the way the car drives... it is great!



Randall,

Many th;anks. As long as I'm not doing any permanent damage to the car with the leaks, I'll keep driving it and keep my eye on the levels. I routine check them, anyway, so that is not a problem.

I guess I just think of the TR# as the worlds greates car, so I want it to act that way... Ha, ha.

 

[poolboy]

Leaks are usually manageable. Now..loosing all your oil at one time..well that's another matter.
But you're lucky; you not only have a convenient engine oil dipstick, but probably a tranny oil dipstick too.
Maybe Triumph thought they had the tranny leaks licked by the time they made the TR6 because they made it a little harder to regularly check the level in those transmissions.

 

[TR3driver]

Don't recall where offhand, but some factory document talks about 500 miles per (Imperial?) quart being the lower boundary of acceptable engine oil consumption. Said something like you might want to try a heavier grade of oil
I've driven engines much worse than that with no apparent ill effects (once took me 48 quarts to get from Houston to LA in a friend's pickup truck); but at some point it becomes irritating/embarassing enough to fix.

Losing a quart/1000 from the gearbox would irritate me enough to plan on fixing sooner rather than later; even with the dipstick & fill hole accessible from inside the car.

BTW, in case anyone is wondering, the dipstick & fill hole were deleted in 1959, at TS50,000 when the castings were changed to accomodate the new starter & flywheel.

 

[Member 10617]

Poolboy and Randall,

Unfortunately, when I had an overdrive added to my car, the old transmission dipstick was eliminated (much to my regret), and now I have to check the level by jacking up one side of the car, putting some oil in the transmission, lowering the car, and seeing how much runs out of the fill hole. Each time I have done this (twice since 2010), I have had to add oil (about a pint each time).

It was so much simpler with the old fill hole/dipstick combination!

Randall,

You mention using a heavier grade of oil. I am using Red Line MT-90 75W90 GL4 Gear Oil in my transmission. If I were to switch to a heavier grade of oil, what would you recommend?

 

[tdskip]

Forget about it's table manners.

Well said Ken, well said.

 

[Member 10617]

Just so I'm not misleading anyone... It's not the mess of the oil that concerns me, although I'd rather not have that, but what the oil leak(s) may mean for the health of the car. If no damage is being done, as long as I keep the levels up, then I won't worry about it's table manners. (Yes, well said, Ken).

I do wonder if another grade or brand of oil may have less of a tendency to leak. for example, I've heard that good quality synthetic oil has a tendency to leak because it gets into places other oils do not.

I'm also very curious about the "mechanism" of this particular leak. Apparently the little hole I see on the bottom of the transmission is some sort of drain hole. And from what has been written above, apparently when oil leaks into some part of the bell housing, it can leak from that little hole. (I have no idea if this is so or not.) So, apparently the little hole is some sort of "safety valve" to draw off this oil, and "should" leak. All this because one of the inner seals is not holding properly. In all that I have read about Triumph TR3 transmissions, I have never found anything about this.