Transmission Leak--Very Specific Question - PeachParts Mercedes-Benz Forum

shertex · #1 04-24-2007, 03:56 PM

I have a 722.418 transmission. I have finally isolated my leak. Just above the pan, just under the cooling line, on the left side of the transmission just behind the bell housing, there is some sort of a plug about the size of a half dollar that takes a 14mm Allen wrench. This is the source of the leak...it appears to be fully tightened.

What is this? Can it be easily resealed? What do I need to do? Is there any risk?

Thanks for any help/advice anyone can provide.

david s poole · #2 04-24-2007, 06:02 PM

this is a plug that closes the hole for the reaction valve on the front band.tightening it will not REPEAT not stop the leak but may crack the case.unscrew it and fish out the reaction valve carefully[there is a short rod at the end that goes into the band on one side] there are two o rings that fit in the hole [or on the valve i forget which] and seal the leaks to the outside.you will probably find that the old o rings are petrified and are so hard that they will crack and break coming out.the dealer has the o rings.

MB STARS · #3 04-24-2007, 06:04 PM

That is call reaction valve for B1 brake band you need to replace two seals part number are 005-997-80-48 and 016-997-34-48 and 140-277-01-51 pin holder after unscrew the plug you can pull out the reaction valve replace seal with new seal and new pin holder when you put the valve back make sure the pin is in the hole of B1 brake band.

shertex · #4 04-24-2007, 06:07 PM

How much labor is involved for someone who knows what he's doing?

david s poole · #5 04-24-2007, 06:20 PM

about 15 mins.

shertex · #6 04-25-2007, 10:04 AM

Interestingly, when I inquired at the dealer, they claimed that there's a risk of losing the pin....so they need to drop the pan, etc., etc... And they want to charge me $350-400!!! Apparently, they're quoting the price ASSUMING that the pin is going to fall into the transmission, even though hopefully it won't.

While they don't sell the O-rings by themselves, they (the parts dept.) sell the plug with the O-rings for $11 (part # 203-540-02-53).

From the way a couple of you guys have described it, it sounds like the simplest thing in the world....is the dealer exaggerating the risk??

brewtoo · #7 04-25-2007, 11:23 AM

Seems like a lot of money to drop the pan.

Perhaps you should ask an indy.

shertex · #8 04-25-2007, 11:30 AM

I will use an indie.

Talked to MB serivce manager..."We have to do things by the book...can't commit to a price then drop the pin and eat the extra labor...etc...." I understand his point....just seems excessively cautious.

Main question at this point: what's the likelihood that pin could get "misplaced?" Because that would surely involve extra labor.