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Getrag/Muncie HM-282 gear oil coming out of vent

369 Views 8 Replies 2 Participants Last post by  robuz24
Hi all,

My 1990 Z24 is having a problem; gear oil, from the Getrag/Muncie HM-282, is coming out of the strut tower mounted vent pipe, when at sustained highway speeds.

I've topped up the fluid, and ensured the gearbox was not overfilled. I thought all was good until I parked the car after once again travelling at highway speeds.

Does anyone have any ideas as to why the vent continues puking gear oil?

Thanks for your help!
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How much oil is in it? 5 pints is the proper amount.
Amsoil Manual Synchromesh is excellent in these transaxles.
Butch_n,
I topped-up the gear oil to the MAX line on the little dipstick.

Thanks for the gear oil recommendation. To top-up, I use GMs recommended fluid carrying p/n 89021808. This number comes up when the original p/n 12345349 is keyed into the GM service desk computering machine.

Anyways, the gearbox is kicking-out oil from the vent line and I don't know why. I scoured the interwebs and came up with little that would apply, considering my Muncie is/was not overfilled...
The dipstick should be close to the correct amount. But, it may have been replaced with the wrong stick. You never know with a 33 year old car (unless you have owned it since new and never let anyone touch it). To know for sure, take the drain plug out and measure how much actually comes out. Let is sit for a bit to drain all of it out. It takes awhile to completely drain. Be sure the car is sitting so as the drain is at the lowest point.
The required 5 pints IS the correct amount for a J, regardless what the dipstick may read. If it has 5 pts in it, it should not be coming out of the vent. I'd suspect it's actually over filled. Here are the two pictures taken from the manual:

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These pics are great! I have owned the car for 6 years and never had an issue with gear oil coming out the vent until 2 days ago. With that said, I cannot guarantee the dipstick is proper for this car. However, I owned another Z24, which I swapped a '89 Muncie into, and it's dipstick appears the same length. The colour of the lock handle is red on this car, opposed to the '89's black handle. Nevertheless, I have driven this machine around for 6 years and until now, I haven't ever had a overflow symptom such as this.

Isn't it possible for a seal to be bad, which would cause extra air to be drawn into the gearbox, which in turn causes the oil to foam-up with air bubbles, and cause the overflowing symptom? I don't know for sure, obviously, but am hopeful someone had resolved this same symptom.

I'll soon drain-out and measure the oil volume.

Thanks again!
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Isn't it possible for a seal to be bad, which would cause extra air to be drawn into the gearbox, which in turn causes the oil to foam-up with air bubbles, and cause the overflowing symptom? I don't know for sure, obviously, but am hopeful someone had resolved this same symptom.
I suppose that could be possible. I've never had it happen, but that doesn't mean it can't happen. However, that leads me back to maybe too much oil in the case. Excess oil will whip and foam up. Which may lead to what is happening. Maybe someone will see this thread and recognize the problem. Sorry I can't offer anything else, I'm stumped.
I suppose that could be possible. I've never had it happen, but that doesn't mean it can't happen. However, that leads me back to maybe too much oil in the case. Excess oil will whip and foam up. Which may lead to what is happening. Maybe someone will see this thread and recognize the problem. Sorry I can't offer anything else, I'm stumped.
I figured out the problem with the transmission gear oil puking out from the vent. I browsed troubleshooting steps in the service manual to find two reasons for gear oil to eject from the vent, which are:
-Transmission is overfilled (as you said),
-air being drawn into the transmission from the "level indicator" (dipstick) plug.
Now, my transmission oil level was barely registering on the dipstick, and I have noticed the cam lock mechanism left the plug feeling loose in the transmission. So, I resolved to install a snipped washer as a means of taking up some air space between the pivoting camlock handle, and it's interfacing surface. Then, I recalled how my previous 5 speed Cavalier had a washer as well, but it was a factory installed spacer. I then remembered the damned metal disc kept slipping off and falling to the ground.
Sope, I topped-up the gear oil, installed my little McGyver hack to the dipstick plug, and went for a burn; the car no longer spits gear oil from the vent.
Thanks for responding and pitching ideas; you got me brainstorming the symptom which led to the solution.
Thanks again :)

Adam
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Hello!
Update time! Ok, so shimming the dipstick worked, or so I thought!
My dipstick is red, which I found odd... Anyways, the vent puking continued, so I drained the gear oil to find the contained volume was 3.25 liters; 0.75 liters overfilled, eventhough the red dipstick barely registered a level at all.
Sope, I figure the red "level indicator" I have is not meant for my gearbox.
Since I'm having a hard time finding a proper replacement, could someone post a few good pics of their 1990 MG2 5TM40/Getreg-Muncie HM-282 dipstick for me? Perhaps the pic could include a tape measure lined-up along side? Knowing the proper length will greatly help with my small endeavour to modify the dipstick I have
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