I'm installing a quality used transmission in my 300sdl. To maintain warranty, I need to replace the external seals. The three that I have questions about are the front seal, front pump o-ring, and rear seal. Using the ATSG manual as a reference, I thought that the front pump had to come out to replace the front pump seal. This is clearly not the case; I've re-attached the front pump. However, the manual calls for using a "non hardening sealant" on the bolts. What is an appropriate product?

As far as I can tell, the front seal needs to be pryed off the front with needle nose pliers or some similar technique. The ATSG manual is mum on this. It looks the same for the output shaft and rear seal, however, is slightly complicated by needing to remove the output shaft. Please correct me or send any tips.

Finally, the front pump o-ring seems to sit on the exterior of the front pump. What holds it in place? It can't be the torque converter, can it? Wouldn't the TC just chew up the ring? Again the ATSG manual is unclear about this.

All advice is appreciated.

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Alex

1986 300sdl

The pump o ring is around the pump body, the pump has to be totally disassemble to change it, when you re installed the pump make sure you can turn the input shaft. you will need a 30mm or 1 3/16” deep thin wall chrome socket to remove the rear yolk. The thin shim goes between the yolk and bearing. I use lock tight anaerobic sealer around the threads of the bolts, ½ inch is all you need. If the o ring is not leaking do not change it. If you do not assemble it right the Trans will fail.

This sure sounds like a catch 22 arrangment to me. As C32 states the pump must come out to do the o-ring.

Funny thing about the warrantee. The only thing you are making more secure with these seals is the trans ability to not leak. I suppose that is a warrantee item. The problem with this is that in this arrangment you have thus released the trans supplier from any warrantee of the seals and increased the likelyhood of a problem because you did the work (any fault in that area becomes your baby). A good tech replacing seals will probably have a good chance of not leaking but the trans as it sits is probably as likely to make it through the warrantee period as the newly resealed one will, maybe more likely. If your reseal works for the warrantee period then you will have a better product but by working on it in this fashion I imagine you will destroy the warrantee on about everything.

That supplier's got a real good scam going with that warrantee.

You may have already done the deed here, but given your choices I would have accepted no warrantee on the seals and left it alone. By taking it apart I can see no way that a warrantee could be given on whether it even works now!

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks C32AMG. I replaced the front pump seal and front seal this morning. It did require taking off the front cover, and an extra set of hands to release a spring plate. I used Permatex Hylomar to seal the threads of the holding bolts.

Part of the folklore for this job is that its easy once the tranny is out. I strongly disagree with this asessment. It requires a very clean environment since you open up the tranny. You need a special tool or an extra pair of hands to disassemble the front pump. Some times the K1 clutch comes out with the front cover. The stack of toothed plates make it a bear to reinsert.

When I get the old transmission out of the car I may make a web photo procedure for doing this.

I got the tranny from Potomac German Auto. They are well respected. I told them I was installing it myself. They didn't offer up any claims of voided warranty based on this.

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Alex

1986 300sdl

Interesting, I have bought many things from Potomac and never had such a request to secure warrantee.

I would consider them one of the best salvage yards.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

I bought a good tranny for my wife's 190D and they had the same requirements (change seals and send them the proof of purchase for the seals to get the warrantee)
I did not and its 1 yr and no problems so far.

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1982 300SD (214 k, excellent shape) kidmobile running mostly biodiesel, gets 31 mpg hwy with 2.82 rear from a euro 500SEL



1976 115 body 240D 4-speed (traded for Jeep parts) - Engine lives on in my CJ7