w126 300sel transmission oil leak
 

1988 300sel with 107k miles

A few weeks ago I noticed transmission fluid (small puddle) on the floor located under my 300sel.

I thought that I might have spilled some tranny fluid from a nearby quart that was lying around.

Last week I drove the car to the grocery store and noticed the transmission slipping. It slipped right after I took off and just before the next gear kicked in.

It drove fine after so I thought it was just a random thing.

I pulled into the garage and checked the tranny fluid level.
Fluid level was low and so I added 1/3 of a quart to bring it up to the Minimum line. I added a little more fluid and brought the fluid level to the midpoint of the max min range. Engine was running while I added and checked the fluid. Drove the car around and transmission shifted fine, no slipping.

Monday morning I noticed a large transmission puddle under the car again.

I replaced the engine mounts and then decided to drive it to a reputable transmission shop.

I received a call from the shop today and they indicated the following:

Transmission observed leaking at the front, between the tranny and the engine.
Possible bad Seal
Maybe Converter hub, Converter Seal, or pump bushing

Unable to further diagnose without opening the transmission.
$600 would be worse case scenario on the low side. Would cover dropping the tranny and replacing seal.

$1000 would be worse case scenario on the hi side where they would really have to do some more work and replace necessary parts (converter, pump bushing etc)

The transmission has 107k original miles and I have only noticed a slight delay when shifting from Reverse to Drive. When I switched over to Redline D4 tranny fluid that delay went away.


I can get my tranny rebuilt and installed at a very reputable shop for $2,300 but don't want to go that route until I know whats going on.

Any advice is greatly appreciated

It _could_ be any of those things, but first make sure it's not leaking out from the vacuum shift modulator pod on the side of the transmission. Basically, you either have to take their word for it, or crawl under there and see for yourself where it is coming from.

You have the typical front bushing leak going on, I am sure the rest of the external case seals are on their way out also. The trans does not need a replacement converter unless the snout is in poor condition due to the bushing, as there is really nothing to wear inside of it... it is not a lock up unit.

How well does this reputable shop know the 722.3? Sun Valley Mercedes Transmissions this place apparently has great units, many people on the board have them installed. If I did not build my own, I would buy one from there.

I have 316k on my OE internal trans in the 300SEL, PO spent the money to reseal it and the shop did not replace the reverse clutches. :rolleyes: I have a very slight cold 2-3 flare as the orings are tired in the K1 drum. Also installed the Superior Transmission shift kit long ago and it really cleaned up the operational pattern within the trans.

Not sure if I would waste $1000 to have it resealed only, price seems fair considering the labor to R&R the trans and labor to reseal the unit. Paper and rubber kit is maybe $100. If you could have the shop reseal and do reverse clutches for $1000, I would do that and get on with life. Reverse is right behind the pump...which has to come out to be fully rebuilt. Inspect the front flex disc while in there, it could easily need a replacement.

$2300 seems way high seeing how simple the 722.3 is in your 300SEL.

What would be a good price for a rebuild?
Just to have an idea

I could not tell you what I deem fair as I rebuild my own transmissions and live in the south, you are in CA where cost of living is very high. Perhaps shop rates are higher due to some odd environmental laws and lease/rent of the shop is high. Plus you are driving a Mercedes... :rolleyes:

Does $2300 include new B1 and B2 bands or at least relined? All new steel plates with the clearances to spec? Valve body upgrade? I have torn down ZFs from 'quality builders' that were mixes of all sorts of garbage. Reused steel plates, mixed friction material. Sad really considering what people paid.

If you have the ability to drop the trans yourself and reinstall, you could save quite a bit of money.

Investigate Sun Valley. Not sure how close to you they are, but they are well known and I would assume do installs also.



Hope it helps.