230SL 4-speed transmission leakage

[friendofaustria]

Hello forum members,

my 66 230SL manual transmission is leaking. After checking of all leakage sources for such transmission, the location of the leakage was found. leak is between the bell-housing and the transmission  .
I was told that the surface of the bell-housing is not 100% perfectly flat & even. Not sure how that can happen. A slight "scalping" together with a custom made Paper gasket may help to eliminate the leak.  What are your thoughts and experiences and/or advise for me. See attached picture of removed transmission.

regards
Gerhard
1966 red 230SL

[georgem]

Hi Gerhard
I assume you have oil coming from the bottom of the join between the bell housing and the engine - a bit of good news- bad news. The good is that this joint was not meant to to be a fluid seal. The source of your oil is either the engine (via a leaking rear engine seal) leaking into the cavity OR transmissioin fluid - manual or auto coming from the front seal. You may figure which it is by the type of liquid on the floor but sadly, the solution is for either the engine and or the transmission to come out to replace the bad seal. The good news about taking the engine out is it gives you a chance to detail the engine compartment ( hows that for looking on the bright side!!)
Cheers
George

[ja17]

From the photo, it looks like you have the transmission out already. Normally a sealing compound is used on the two machined surfaces and it works fine. Yes, things can warp and become uneven over the years.  If you decide to add a paper gasket, use some very thin material (like newsprint) and seal with gasket shellac on both sides also. Adding too thick a paper gasket, will change the critical shimmed clearance of the input shaft and bearing. Go ahead and change the transmission front seal while your at it. Also check the slotted nut in the tail shaft to make sure it is not coming loose.

[Benz Dr.]

I use a piece of sandpaper glued to a piece of glass to get a level surface. Place the bell housing on the sandpaper and swirl it around until the entire surface is smooth. This method works on all sorts of small pieces that require a flat surface to achieve a good seal.

 The front input shaft seal requires a special tool to install correctly. I would not change it unless you can get this tool or have one made.