Automatic Transmission Leak

[DavidBrough]

I have been suffering a gradually increasing fluid leak from the right hand side of my auto transmission and as it is now actually reaching the floor feel I should do something about it. The leak seems to be coming from the pressure modulator area and I am hoping that changing the gaskets will fix it.

My question then is this a straight forward job. It seems that the modulator and mounting body should come off the side of the gearbox if I drain the oil and remove the exhaust heat shield. However, I am always wary of auto boxes and don’t want to upset anything. Has anyone done this job before and will the modulator and body come straight off and allow gasket replacement or is it more complicated than that.

Thanks



David Brough
1969 280SL

[ja17]

Hello David,

Not much room to work, but the modulator diaphram and and gasket can be changed without transmission removal.  You may want to check to see if you have a loose transmission filler tube at the pan, loose pan bolts or any other loose bolts on that side of the tranmission.

Joe Alexander
Blacklick, Ohio

[DavidBrough]

Thanks Joe,

I just needed to be sure I wasn't starting something that required transmission removal to put back properly.

David Brough

[Bob G ✝︎]

Diaphram part # 112 270 00 79 is what I received from the classic center here in the USA. I am told they leak and to check the pan gaskets and hose connections. I hope that is all it needs. The old girl getting too fragile for even a spin around the block. Prehaps some good therophy and some new parts will put so spring in the  old girls life again.
Bob Geco

[DavidBrough]

Well I eventually got round to removing the modulator to replace the leaking gasket but it proved quite tricky to remove and I am not sure how best to put it all back together or if I have to remove the large plate the modulator is mounted to.

I attach photos of the plastic modulator mounting and gearbox with modulator removed. The problem with removal was the little arm on the gearbox that slots into the plastic mounting plate and small steel pin. When I eventually got it apart my first thought was how am I going to put that back. Does anyone know if this should all go back together without having to remove the large mounting plate. I don’t want to labour for hours trying to do the impossible?

At first sight it would appear to be straight forward if the cut out in the plastic mounting was open instead of closed as it would then slot straight on.

Hope these ramblings all makes sense to someone.

Download Attachment: Gearbox.JPG
38.15 KB

Download Attachment: Modulator.JPG
53.02 KB


David Brough
1969 280SL

[DavidBrough]

Success, I think.

Managed to replace the modulator after deciding to remove the side plate on the transmission tunnel and detach the solenoid arm. Still took a lot of fiddling around but it seemed to go back together alright. Can’t test it yet as I am in the process of changing the exhaust as well. I felt it would be better to remove the modulator with the exhaust off and I was right, it would have been very difficult with the exhaust in place.


David Brough
1969 280 SL