Getrag 260 is leaking - but why?

[bmw-slangen]

I have a very strange gearbox leakage and really need expertise help!

It is a E30 323i -85 with a standard manual Getrag 260/5 gearbox.

When I drive hard on the track, it starts leaking quite badly from inside the bellhousing.

But when driving "normal" it doesn't leak at all.


I'm really hoping that someone else recognize this problem and can help me!




--- Here is some more in-depth but important details ---

I can drive "normal" without any issues.
The problem occurs when driving hard on the track.
The first stint (20 min of hard driving) is usually not a problem.
Halfway through the second stint (usually you rest for 20 min between stints), it starts to leak really bad.

I tried with the original gearbox two times and then I also tried with a spare gearbox - same result.

It is 100% confirmed it is gearbox oil and not engine oil or brake fluid.
It is 100% confirmed it is coming from within the bellhousing.

I verified the vent hole is not clogged (goes for both gearboxes).

I use ordinary ATF "Dexron III" transmission oil (goes for both gearboxes).

I verified the fill level is according to specifications (goes for both gearboxes).
Means that I fill up to the fill plug level with the car level.

On all occasions it's been basically bone dry around the vent hole (so nothing comes out from that one).

On the original gearbox I
- replaced the input shaft seal TWICE (part #9)
- replaced the sealant of the housing cover and the screws TWICE (part #6 and #7)
- made sure every time that the housing cover was oriented properly to the oil passage

http://www.realoem.com/bmw/enUS/showparts?id=1471-EUR-01-1985-E30-BMW-323i&diagId=23_0579

On the spare gearbox I
- replaced the input shaft seal (part #9)
- replaced the sealant of the housing cover and the screws (part #6 and #7)
- made sure that the housing cover was oriented properly to the oil passage

http://www.realoem.com/bmw/enUS/showparts?id=1471-EUR-01-1985-E30-BMW-323i&diagId=23_0579

On the spare gearbox I
- sealed (from the outside using RTV) around the layshaft bearing visible in the bellhousing (part #24, #21 and #22)

http://www.realoem.com/bmw/enUS/showparts?id=1471-EUR-01-1985-E30-BMW-323i&diagId=23_0144

I pressure tested (around 1 bar) the spare gearbox and nothing...
Not the slighest indication of a leak (checked by listening as well with soapy water)...

[TobyB]

Pull the standard vent out, tap and thread an elbow into the hole,
(or just secure an elbow in there somehow)
and run a hose up to
a catch tank in the engine bay.

I bet that solves it.

Somehow, you're pressurizing the gearbox.

Oh, are the locating dowels in place on your gearbox/engine?
Have you checked the pilot bearing?

I use MTL in the racey car, but ATF should work ok...

hth,
t

[Wolfman]

Drain the ATF which doesn't belong in a 260 and fill with Swepco/ redline/royal purple gear oil. Then go out and enjoy a smooth shifting leak free car.

[e30davie]

My understanding is that some G260s want ATF and some want normal gear oil. Markings on the bellhousing suggest which way.

Presumably the input shaft gearbox seal is leaking but only with sustained high rpms of the input shaft.

When you changed the input seal on your current box did you take not as to weather the shaft itself was worn where it contacts the shaft? given the age of these gearboxes it wouldn't be surprising if the shaft is worn down a bit. Happens on front and rear main seals on crank shafts on older engines.

Having said that i would have thought that if that was the case it would leak all the time. But you never know....

[bmw-slangen]

Pull the standard vent out, tap and thread an elbow into the hole,
(or just secure an elbow in there somehow)
and run a hose up to
a catch tank in the engine bay.

I bet that solves it.

Somehow, you're pressurizing the gearbox.

Oh, are the locating dowels in place on your gearbox/engine?
Have you checked the pilot bearing?

I use MTL in the racey car, but ATF should work ok...

hth,
t

It's most probably a good practice to introduce such a solution (might do it in the future).

But it will not solve this problem (unfortunately).

The area around the vent hole was completely dry, so no oil has leaked out through the vent hole.
The gearboxes (I've tried two different) can not be pressurized since I've checked the functionailty of the vent hole every time before putting back the gearboxes. The tiny pressure that will be built up will immediately be vented out of the vent hole.


Dowel pins been inspected, but will do it again.
Pilot bearing is one suspect (will inspect it - but new pilot bearing already been ordered from BMW so I will change that regardless).


My main suspicion right now is that the input shaft somehow wobbles badly during certain circumstances causing the input shaft seal having problems to seal it properly.

[bmw-slangen]

Drain the ATF which doesn't belong in a 260 and fill with Swepco/ redline/royal purple gear oil. Then go out and enjoy a smooth shifting leak free car.

ATF does belong in a Getrag 260, for example those found on the E30 and some E34.

They were filled with ATF from the factory. And the user manual also states you should use ATF or straight 20/30/40 SAE engine oil.

Not saying there are better alternatives (lasting longer, better in cold climates and so on) - but for this specific leakage problem it is not relevant.



Can you elaborate more why ATF oil will leak and not eg Redline gear oil?

[bmw-slangen]

My understanding is that some G260s want ATF and some want normal gear oil. Markings on the bellhousing suggest which way.

Correct, but this was actually introduced more like 5-10 years after this car was manufactured. Around 1985 it was only ATF. It was more like 1990 and onwards they started with other type of gearbox oils.

Presumably the input shaft gearbox seal is leaking but only with sustained high rpms of the input shaft.

When you changed the input seal on your current box did you take not as to weather the shaft itself was worn where it contacts the shaft? given the age of these gearboxes it wouldn't be surprising if the shaft is worn down a bit. Happens on front and rear main seals on crank shafts on older engines.

Having said that i would have thought that if that was the case it would leak all the time. But you never know....

Yeah, I having similar suspicions.
* Either the input shaft is wobbling really bad but only under certain conditions, and the input shaft seal is then not able to seal properly.
* Or it has problems with high RPM, as you stated. I have tried to simulate this (driving at low gear under long time on the street) but couldn't replicate the problem.

Wear on input shaft was definately a concern, so it was checked when assembling the new seals (verified on both gearboxes). However I will do a very close and detailed inspection of the input shaft regarding this issue once again - just to be absolutely sure.

[bmw-slangen]

Ok, let's get straight to the point - you were right! :oops:

The problem must have been overflow from the vent hole!
But not due to expansion, foaming or wrong gearbox oil and so on.


I wanted to recreate the problem, so I had the gearbox on the bench,
filled to specified level and was running the input shaft with a drill.

With the gearbox completely level, nothing happened. Not a single drop.

But then I tilted the gearbox 45 degrees to simulate heavy breaking,
while the input shaft was spinning.

And now it basically was pouring out gearbox oil from the vent hole!

https://www.youtube.com/watch?v=LbVn3-wNsG0

So the solution was to attach a hose (using an ordinary hose clamp) to the vent hole,
and it was then routed up as high as possible in the engine compartment,
with a small breather filter at the end.

When you had the gearbox tilted down it was quite easy to attach a hose,
and then secure it with a hose clamp (I tried and couldn't even pull it off).
But with the gearbox in it's installed position I declare it IMPOSSIBLE to get to that vent hole!



So I was wrenching like cray from 06.00 to 21.00 entire Friday to get the car ready for the track day the very next day.

Up at 05.30 on Saturday and away to Ljungbyhed (a former military airfield) - and success!

I could put in lap after lap without a single problem! :D

https://www.youtube.com/watch?v=_z0_jcdsd8k

Thanks all for leading me into the correct path and actually thinking in other directions.
I still can't get over how bad I could misjudge the evidence in front of me.
But I should have known better - I know that oil in turbulent air flow can do basically anything!

[TobyB]

Sometimes the best way to learn is to learn by doing!

Glad you got it fixed.

t

[Digitalwave]

Just wanted to thank bmw-slangen for helping me out on the issue, both with this thread and via PM.

I have had every leak imaginable on my Getreg 260. Input seal, output seal, selector rod seal, detent pin cover. After finally curing all of them, I was horrified to see more fluid covering my tranny! It didn't take long to notice it is coming from the top breather vent. When I would move my vent cap after driving the car, it would hiss letting the pressure from inside the tranny out.

I disconnected my exhaust, shift linkage, CSB, tranny support bracket, loosened the motor mounts, removed the clutch slave cylinder, and removed the bracket/brace under the bellhousing that sits behind the subframe (preventing your motor from shifting too far forwards if you have bad driveline mounts). This allows you to drop down the tranny enough to give a little more clearance to install the breather hose.

First push off the plastic vent cap. You're going to be working blindly, but tighten your hose clamp a little bit so it's not too loose on the 1/2" hose, and then slide it over the breather nipple based on feel. Tightening the hose clamp is the hardest part with the limited space, but mine went on and it was on there solid. Raised the tranny back up and checked the hose. It doesn't have much room, especially the large 1/2" hose, but it wasn't pinched so it should flow freely. Then I ran the hose up near the fuse box and capped it with a breather filter from the auto parts store.

If you track or even autocross your car you should go ahead and do this! I wish I had known last time my tranny was out, as it would make the job a lot easier.

Thanks again bmw-slangen!

[zaq123]

interesting....
I watched the vid and it looks like you had the fluid already sitting in the tube vent....before you started the drill. Maybe there is something wrong with the vent valve (under the tube)?

BMW redesigned that part 3 times for E30. The latest one eliminates the plastic cap, tube and the open top vent valve. It looks like it is all one unit now

p/n 23131204841

[bmw-slangen]

Interesting!

I was under the impression that all E30 Getrag 260/5 did have the plastic cap, and the one-piece-metallic was used in E34 Getrag 260/6 and others.

So then you might encounter the one-piece-metallic on late E30's then.




I only have some theories why this actually happens (would like in the future to chop up a Getrag 260/5 and have a closer look).

But I suspect that the pickup point/tube for the vent hole at the top is located at a "non-optimal" spot inside the gearbox.
Under normal conditions this pickup point/tube is in free air and the venting works just fine.
But when under heavy breaking the pickup point/tube is submerged and the pressure inside builds up slightly and simply pushes up fluid (instead of air) through the tube and it flows out from the vent hole.

Just a theory, but I suspect that is what happening.

And this internal solution maybe was updated on later gearboxes, we really don't know how many changes Getrag made internally on the Getrag 260/5 during the lifespan of the E30.

[zaq123]

E21,E30,E36,E46,E90,E91,E92,E93.... the above breathe is the only design currently offered to all the above models +

There is no pickup tube, what you see in the breather valve is what you get. On older models there is similar but open valve is buried under that little tube/black cap

Interesting!

I was under the impression that all E30 Getrag 260/5 did have the plastic cap, and the one-piece-metallic was used in E34 Getrag 260/6 and others.

So then you might encounter the one-piece-metallic on late E30's then.




I only have some theories why this actually happens (would like in the future to chop up a Getrag 260/5 and have a closer look).

But I suspect that the pickup point/tube for the vent hole at the top is located at a "non-optimal" spot inside the gearbox.
Under normal conditions this pickup point/tube is in free air and the venting works just fine.
But when under heavy breaking the pickup point/tube is submerged and the pressure inside builds up slightly and simply pushes up fluid (instead of air) through the tube and it flows out from the vent hole.

Just a theory, but I suspect that is what happening.

And this internal solution maybe was updated on later gearboxes, we really don't know how many changes Getrag made internally on the Getrag 260/5 during the lifespan of the E30.

[e30davie]

What an interesting outcome. Who would have thought.

Least its a relatively easy fix!

Back in my 4WD days we used to extend vent tubes to stop water getting into diffs and gearboxes. I have no more to add to this anecdote.

[zaq123]

Old breather design





new breather design



Mybimr's pics