Author Topic: Rear main seal leak ATF?  (Read 111 times)

daantjie

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Rear main seal leak ATF?
« on: 02 October 2020, 05:01 PM »
Hi guys
I've had a slow drip from the bellhousing for a while now, but the colour is largely red, as in ATF.  Is this typical of a rear main seal leak?
I would have thought the leak would be mainly engine oil ???
Cheers
Daniel
1977 450 SEL 6.9 - Astralsilber

karmann_20v

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Re: Rear main seal leak ATF?
« Reply #1 on: 02 October 2020, 06:54 PM »
Hey Daniel, you are correct an RMS leak would be motor oil. I think I read somewhere (W126 forum maybe) that there the torque converter has a drain drain plug, the converter being in the bell housing a loose drain plug could be a potential cause for your issue.

daantjie

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Re: Rear main seal leak ATF?
« Reply #2 on: 02 October 2020, 07:11 PM »
Thanks Florin this is a good tip, I totally forgot about the drain plug, hmmm, now I'll have to check it out.  That would be much easier to fix than a rear main seal ::)
Daniel
1977 450 SEL 6.9 - Astralsilber

karmann_20v

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Re: Rear main seal leak ATF?
« Reply #3 on: 02 October 2020, 08:42 PM »
No worries! I hope it's something as simple as that. Removing transmissions is never a fun job without a car elevator and transmission hoist.

daantjie

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Re: Rear main seal leak ATF?
« Reply #4 on: 02 October 2020, 09:51 PM »
Nope, torque converter plug is good.  I think uncle Kent nails it here, I am pretty sure the leak is from the front of the trans, from either the torque converter seal or large o ring(or both) he shows in this clip:

https://www.youtube.com/watch?v=mYs-5i3wgUE

Oh well, at least ATF has some detergents in it, so I'll just keep wiping it down ;D  No way I am pulling the trans on this bad boy just for a minor leak...

Cheers
« Last Edit: 03 October 2020, 09:31 AM by daantjie »
Daniel
1977 450 SEL 6.9 - Astralsilber

Jed

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Re: Rear main seal leak ATF?
« Reply #5 on: 03 October 2020, 08:35 AM »
Ok, I give up.  whats with the orange juice?

1979 Mercedes 6.9 #5206 - restored
1979 Mercedes 6.9 #6424 - ongoing restoration
1976 Mercedes 6.9 #484 - restoration?

daantjie

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Re: Rear main seal leak ATF?
« Reply #6 on: 03 October 2020, 09:29 AM »
Ok, I give up.  whats with the orange juice?

I think it's just some grampa humour, I recall in one of the other clips he talks about just having a nice drink on hand while you tinker ::)
Daniel
1977 450 SEL 6.9 - Astralsilber