Transmission Drain Plug and Service

[dirtrack49]

Hi all, this is odd. I was in the process of doing a transmission service on my 1966 230SL Automatic, and when I took the drain plug out, I found the aluminum washer seal to be welded to the plug. I tried to chisel it off with no success. I am thinking that the last person to work on it, might have installed the wrong aluminum seal on it since it appears to be pushed up on the cone to the point that I can not remove it.

I am thinking that I should just put another seal on top of it. However, it would be nice to get the old seal off. My thoughts, chisel it off which did not work. File it off without destroying the plug. Cutting it off with a saw or Dremal tool with out destroying the plug.

Or, better yet, can the transmission plug be found at a supplier source? So far, I have not located a supplier that has the drain plug.

TIA,

Tom L.
66 230SL Auto

[doitwright]

I’m not sure this will help you but on my Acura MDX when the Jiff lube place reported to me that the threads on my oil pan drain plug opening were stripped I went to YouTube for a solution and found that the threads in the pan went deeper than the original bolt. The solution was to get a longer (but not too long) bolt of the same thread size and install the same washer than you would with the original. I did that 3 years ago and no leaks to this day.

[dirtrack49]

Thanks Frank for the info.
Now it seems I might have a new problem? Got everything apart to do the transmission service and take a look at this picture. Where is the filter? Is there something missing here?

Tom L.

[dirtrack49]

Ooops!  I guess I might have CRS. I am thinking that the earlier models have a different trans oil filter? The filter that was sent to me sometime back is for a later car? Or, do they all have the same filter?

I take it that if I remove the 10mm bolt holding the thin bracket and screen in place, it will reveal my filter?

When I look at the different suppliers, they all seem to show the later filter. If there is an earlier filter, does anyone know the part number, or where I can get one?

[Shvegel]

Most likely the reason you don't see an earlier filter is that as a screen with no paper the filter you have is cleanable.  If you don't mind ruining the finish on the drain plug if you soak it in some acid overnite it will probably eat the old seal right off.

[dirtrack49]

Shvegel, thank you very much for your input. I find it hard to believe that everything I have found leads to replacing a transmission filter that does not exist in the first place. Hopefully, someone who has an earlier model such as I, will not be mislead into thinking they need to buy a transmission filter for their 230SL. Neither by the suppliers, nor by possibly this website referring to the later models only. Maybe this thread, will help others with the same problem that I have encountered.
So, if I remove the 10mm bolt in the center of the screen, there is some type of filter that can be cleaned? Any advise on how to proceed?
Thanks again,

[Pawel66]

In case there is an issue with the drain plug screw, the PN for it is N007604014110 (means it is a pretty regular screw) for 113042 and it costs about $3. The seal ring for it comes in the filter service set for 113042. But I suppose seal ring is a standard seal ring.

I do not know how experienced you are, so, no offence, but you need seal rings for all the fitings you disconnected...

When I was doing my filter replacement I replaced all related gaskets that were in the set. Maybe you should ask the more experienced colleagues here if this should be done or can be omitted. But for oil pan to gear box housing gasket - this is the critical one... Or perhaps you have it already - then no point.

I think it is good to drain the hydraulic clutch. There is a seal ring there too.

If you go for ordering filter service set, you may need to look at the plate on your gear box and note the gear box number to make sure you order the proper set. If you order set, you have some of the seal rings there (I think not all, looking at what you disconnected).

What I found challenging for a weekend mechanic was fitting back the oil pan - had to make the mating surfaces even with a socket and a gentle hammer and not to use too much torque when tightening the screws (may want to check what is the required torque).

[dirtrack49]

Thank you Pawel for the part number and your advice.

Yes, I realize that all of the seals need to be replaced since they are all made out of aluminum.

After further investigation, I am now under the impression that the transmission filter kit sold by all of the vendors no matter what year your car is, is for the 280SL only, or at least all 1968-1971 models. Therefore, earlier vehicles do not have nor require a filter kit.

If my transmission filter is reusable, what is the preferred method of cleaning it up? Are there any other items needed besides the pan gasket and sealing rings?

Thanks again for any and all help.

[rgafitanu@gmail.com]

Tom,
I had the same "surprise" when I tried to replace my tranny filter on my automatic. The screen that you see is the early type "filter". Remove the screw, pull the screen down and mount the new filter (backward compatible with the early transmission) with the screw. Or, clean the screen and remount it. I chose to install the new filter and I am keeping the screen as a spare.
After many years the aluminum washer bonded with the screw. I wouldn't use another aluminum washer on top of it, try to remove it with a Dremmel or get another screw as Pawel suggested.
Radu

[dirtrack49]

Thank you Radu, that is exactly what I needed to know. Yes, a surprise indeed. You and Shvegel resolved my dilemma.

I just need to know one more thing before I proceed. Do I need to obtain a screw that is compatible with the later filter, or can I reuse the 10mm bolt from the old screen?

[rgafitanu@gmail.com]

I reused the existing screw (if I remember correctly).

[dirtrack49]

I found out that in order to update the 230SL with the newer transmission filter for the later 280SL's, it will be necessary to replace the existing 10mm original filter bolt with a same size bolt with a slotted screw head. Reason being, there is no way to get a socket onto the original bolt to seat it in the updated filter.

[rgafitanu@gmail.com]

You are right, I remember there was an issue with that bolt. I used a newer pan head Torx screws that MB is using these days (brand loyalty). I try to stay away from slotted screws, if they are stuck it can be a big problem. I replaced several of them from the IP with socket heads.