Automatic - leaking from final drive pan when filling gearbox

[Johanjons]

Hi!

As the topic reads, my final drive pan is leaking oil when i refillwd with new ATF.

I noticed my van shifted gear really strange and i checked my oil level and it was zero.

I didnt notice any spill but filled up with new oil and the oil started to flow, not from the gearbox pan but under the final drive.

I understand the gasket is done, but i wonder, does the gearbox and final drive share oil?

I remember i had to fill it through a tube by losing a screw before. So if they share oil, good then i just need to change gasket. Or is it a seal inside that is broken so the oil travels to the final drive?

Best regards.
Johan
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1981 AC 2L Fuel Injected.
Holdsworth.

[brickster]

First, head over to the transmission section of the FAQ. You will be able to quickly locate the information you need in the AT section.

https://www.thesamba.com/vw/forum/viewtopic.php?p=6236053#6236053

From your photo, it does look like the AT pan has a leak. When did you last check the level (prior to now)?

When you drop the AT pan, share some photos of what the fluid and debris in the pan look like.
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1984 Campmobile Automatic

[Johanjons]

[SCM]

[MarkWard]

I’d degrease and pressure wash the entire drive train. It all looks like ass and a fluid will always drip from the lowest point.

And to clarify for someone in the future. There are 2 pans. One for the differential next to the engine case and one for the automatic. The differential is drained by removing the pan and filled with gear oil through the Allen plug in the side of the differential near the cv flange.

The automatic also doesn’t have a drain plug. You can remove the fill tube and drain quite a bit or the pan has to be removed. You can access the filter with the pan off and it’s filled from the engine compartment transmission dipstick tube. You use ATF Dexron was recommended, but some swear by Type F. I recall 3 QTs on a drain and refill.

[brickster]

[Johanjons]

Thanks guys!

I guess i have some work to do again..

Any recommendation of seals and gasket of high quality that i should get before i remove everything. I am better of just changing everything i can when i remove it.
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1981 AC 2L Fuel Injected.
Holdsworth.

[brickster]

You may be at an advantage being in Europe, but I don't know. Hopefully someone from there will chime in.

Check this sticky out (Resources: Helpful Web Links & Vendors):
https://www.thesamba.com/vw/forum/viewtopic.php?t=128668
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1984 Campmobile Automatic

[jlrftype7]

[raygreenwood]

What people are trying to tell you....cryptically I might add ...is that you have ATF in the gear shift section and SAE gear oil in the differential section.

Most of these Borg Warner based transmissions for VW and some Audi of this era have two seals that need to be replaced at a reasonable interval.

In the early 90's VW/Audi had a technical data sheet that listed on very similar transmissions that thee seal should be replaced at an interval of 7 years or 70,000 miles. If either of the seals fail, the AtF fluid will get into the final drive fluid. What this causes is dilution of the anti-scuff qualities of the final drive hypoid oil. Within a couple hundred miles you can literally destroy the ring and pinion.

Yes, the gear oil can also get into the ATF sectio nand gum up valves and clutches but thats not permanent damage. ATF in thefinal drive oil IS permanent damage.

Any of this type of transmission has this issue with the seals. This included the 003 trans that went into type 3 and 4 cars and the 010 that went into the bay window bus.

The two seals are the mainshaft seal between the final drive and the gear section and the governor shaft seal loacted in the final drive section.

Back in those days it was about a $300 job because its not really invasive to the transmission.

Ray

[Wildthings]

For the differential pan you can just use silicone and do away with using the gasket. Some silicone compounds specifically mention they are good for use with gear oil. Whether you use a gasket or just silicone you want to flatten the area around the bolt holes in the pan, as people tend to tighten the bolts tighter when a leak shows up deforming the pan when doing so.

Do not use silicone on the transmission pan gasket, and don't go hog wild on the silicone you use on the differential pan gasket, just use a judicious amount.

[1988M5]

[ALIKA T3]

The back to back seals have likely failed majorly.
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Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[raygreenwood]

[Shonandb]

When the internal seals between the final drive and the automatic side fail, the automatic fluid typically flows into the final drive so if you remove the final drive plug (17mm), reddish-brown oil will pour out as it will have the AT fluid mixed in with the hypoid/diff oil.

If you remove the plug and find the final drive oil level at it's normal level and the oil is still a normal colour, then the internal seals probably haven't failed and the leaks are external - from the pans, or somewhere else.

I had this happen with my 003 when I was having the 010 rebuilt back in 2019. One day after starting the Bus up I noticed a reddish brown pool under the Bus. I immediately shut it off. When I removed the diff plug, about a quart of reddish brown oil flowed out and there was no red automatic transmission fluid showing on the dipstick.
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76 Westy with a 2.5L Subaru SOHC + Vanagon (010) Automatic Transaxle
Build & Trip Thread: https://www.thesamba.com/vw/forum/viewtopic.php?t=758760
Previous 1973 Panel Bus:
Click to view image

[Johanjons]

Thanks for all the information everyone. I will do some ordering of new gaskets, seals and some other stuff now and check what can be done.

Saw a guy selling a automatic transmission on a facebook group in worst case.

Will update as soon as have identified the issue.

Thanks.
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1981 AC 2L Fuel Injected.
Holdsworth.

[Johanjons]

Hello again,

I have been searching the internet for the correct seals that you are refering to "Back to Back seals", feels like all sites have had different names for them but I found that according to VanCafe, that refer them to Transmission-Differential-seal, they state that in the Bently Workshop Manual, it is refered to the "Pinion seal"

https://vancafe.com/automatic-transmission-differe...9WYiq1oEyT

The pinion seal can luckily be found at BrickWerk - do you think this is the correct one to be replaced? https://brickwerks.co.uk/product/autobox-seal-t3/

PS i also found this blogpost which pretty much described my situation https://gowesty.com/blogs/article-library/automati...RMFvGqYDRR
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1981 AC 2L Fuel Injected.
Holdsworth.

[brickster]

Yes, that's the correct seal, and you'll need two. Notice that each vendor lists the VW part number (089409529D) on the product page.
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1984 Campmobile Automatic

[Johanjons]

So I am not a pro, but this does not seem so good.

It was found in the pan of the final drive. I want to think it is a ball bearing or something, but I have nooo idea from where or what i should look for.

Any idéa?
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1981 AC 2L Fuel Injected.
Holdsworth.

[brickster]

I agree with your diagnosis of not good.

I’m no expert, but I think that these final drive sections are generally bombproof and long lasting. If you have access to junkyards, I would think that even a high mileage unit would be fine as a replacement.

What does the transmission section look like? Do you see any chunks or excess swarf in the pan?
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1984 Campmobile Automatic