grane

Please have your transmission pan A 222 270 05 12 checked for electrolytic corrosion at the filler plug. There is a new improved pan for $125 US that allegedly "eliminates" the problem.
In NA they say the service is due at 70k miles. My buddy who is a 30 year MB Master Tech here and all over the world, says 40k Miles. I'm glad we did.
Cause: Electrolytic corrosion exacerbated by moisture and road salt at the drain plug. According to MBUSA this could cause "catastrophic failure" of the transmission if the leak was not noticed, or the assembly just failed. The replacement transmission is $8k!
If you were going to purchase a certified preowned MB with this transmission of any mileage/age one might consider making sure the new "improved" pan is in place and the service is performed. If you have one now check it.

Don't they teach automotive engineers about electrolytic corrosion?

I don't know how to post pictures but I have several.

B737

isnt this just the 'updated pan' with the taller fill neck?

grane

Can you explain more? Which "updated pan" are you referring to? When was this pan updated and when/how were you apprised of it? How come we were not?

Any other information you have would be helpful.

B737

this thread, post 2, lay out the links that provide the information and discussion regarding the updated oil pan & filler ect.
https://mbworld.org/forums/glk-class...id-change.html

Flypenfly

Why not just replace the plug?

grane

Check it at 35k miles or before 5 years. Electrolytic corrosion and road salt, I reckon. We wash the car and the undercarriage regularly. I'm not sure if there is cladding over it or not.

Why doesn't MB use a non-metallic washer or a disposable heavy-duty plastic bolt??





The best or nothing?

Fagunza

Wow. Thanks for the picture. My dad called it galvanic corrosion when he taught me about it 60 years ago. So, not exactly a new concept.

I expected better from the engineers at Mercedes!

ItalianJoe1

Both the pan and bolt are made of steel, hard to get electrolytic corrosion just from that. Washer is copper, but if it was also steel then it wouldn't crush and seal.

I'd wager that's more from a failure of the coating where the threaded insert is welded into the pan, and rust spreading under the paint around it.

I've not seen a bulletin or "updated pan" about this, but now i'm curious and will look. On the bright side, the pans are pretty cheap, and if this happens and you catch it before it breaks through, it's not a terrible fix, the pan has to come off for the service anyway.