Hello

My 1987 300E has a big transmission leak. The leak only happens when it is running. My mechanic says that there are 2-3 seals involved with the secondary pump and the are prone to leaking.

He suggested removing , eliminating the pump. There is some plate and bolt that is needed and a seal or two.

I understand that the pump is for towing. however with all the different cars out there most tows are a flatbed truck.

Any reasons to not let my mechanic eliminate the pump?

Two reasons:

1) It might not be the source of the leak.

2) If he doesn’t know how to source a pump delete kit, he has no business doing the work.

Sixto
98 E320s sedan and wagon
02 C320 wagon

Thanks for the reply.

There are many leaks some are small and may not be addressed. The secondary pump has a big leak.

He already has the kit he has done many of them.

I am looking for reasons in the future where I will regret having removed the pump.

“I regret removing the secondary pump.” Said no one. Ever

Seriously, too many years on this forum and I haven’t read such a regret. On the contrary, a couple of transmission failures have been blamed on the secondary pump plunger coming loose at speed.

Sixto
98 E320s sedan and wagon
02 C320 wagon

I am impressed that your mechanic was aware of this fix. Don't let him get away.

m:

There are two dynamic seals: 1) The torque convertor neck, which drives the primary pump, and 2) The output shaft. All other external seals are static. None of them are touched by the secondary pump.
Curing the leaks, and eliminating the secondary pump are mutually exclusive.

Just curious have alot of people eliminated the secondary pump over the years?

The shop is Peter Schmid Transmissions, MZF in Burlingame California on the SF Peninsula.

I believe they might be one of the best if not one of the best Mercedes Transmission shops in the world. They have been around since the 70s or 80s and all the dealers in the SF bay area use them. I heard years ago, people in Hawaii would crate up their transmissions and send the to this shop in SF bay area California for repair!!

I am lock to live a mile from this shop!!!

Hmmm Not sure??

From what I understand there are 2-3 seals associated with the secondary pump and they are prone to leaking. This is not in agreement with your statements.

I have a large leak on the passengers side but only when the car is running, I believe this is the secondary pump. I guess you would call this a dynamic leak as it only happens when the car is running. I recall a few months ago sitting watching the car get its California smog emissions test the car was on the dyno for about 10 minutes and there was a good size puddle of atf, I sat and watching it accumulate.

Hello

I am getting close to address the secondary pump leaks.


Giving it some more thought, I am not going to keep the car forever and was thinking if I just had the seals replaced they would last 15 years which is much longer than I expect to keep the car.

Thoughts? Should I have the secondary pump seals replaced or eliminate the secondary pump?

Hello

I just found a related thread on this topic on the mercedes fourms, lots of nice diagrams

Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W126 S,SE,SEC,SEL,SD,SDL Class > Replacing Transmission Secondary pump seal


and here is an excellent reference

http://www.trocki.pl/szymon/automat/tranny_722_repair.pdf

Clean the transmission and find where it’s leaking. The usual suspects on the passenger side are the secondary pump and B2 piston cover. There’s also the dipstick tube and Bowden cable but they don’t see the pressure to leak at the rate you describe. Maybe the cooler return line?

Peter Schmid isn’t the shop it was 20 years ago. I believe it’s changed owners. It used to be the preeminent shop but it has its share of unhappy customers these days. Sun Valley in Pacoima (SoCal) gets far more praise on this forum.

Sixto
98 E320s sedan and wagon
02 C320 wagon

If indeed the secondary pump is leaking should I have them just replace the 2 or 3 seals or have them eliminate the pump?