Mercedes-Benz Forum banner

1 - 14 of 14 Posts

·
Immoderately Caffeinated/ Vintage Moderator
Joined
·
16,392 Posts
Discussion Starter #1 (Edited)
I'm basically thinking aloud here but any input welcome.

When starting cold and D or R selected the car feels like it's bogged ie revs a lot but only moves a little, then it takes off and it shifts and drives fine. I can drive for a couple of hours then stop for an hour and it starts and drives okay.. The trans was rebuilt under 50k ago and as of last week the fluid looked fresh and level okay.

The only thing I can think of is the speed sensor in the valve body? Am I on the right track?

Edit: I'm putting it on Star shortly so will see if it fired a code.
 

·
Immoderately Caffeinated/ Vintage Moderator
Joined
·
16,392 Posts
Discussion Starter #3
Thanks. No codes from Star program. It was suggested it is a sticking valve and the torque converter needs filling at cold start. I stuck some Nulon additive in so we'll see how she goes tomorrow. I ain't throwing parts at it with no codes to go by.
 

·
Immoderately Caffeinated/ Vintage Moderator
Joined
·
16,392 Posts
Discussion Starter #5
Not trying to put the worst news here, but could the transmission be slipping?
Unlikely because the trans was rebuilt less than 50k ago for $5700. But I beat you to it because being the eternal pessimist I already thought the worst. 🙄

Tomorrow I'll do one of two things. Start it cold then restart immediately to see if it resets and doesn't do it, which is unlikely because it didn't throw a fault on star.

Or I'll idle it for a minute to see what happens.

Plus if it was slipping because the trans needs a rebuild wouldn't it do it all the time?
 

·
Registered
Joined
·
6 Posts
I had a similar issue (only in forward direction) where the car would take off from a stop poorly then feel like it "shifted" somewhat harshly and continue on normally. No codes or suspect shift adaptation values with the SDS. The issue was the torque converter lockup clutch. I ended up replacing the torque converter solenoid on the valve body and disconnecting the output line on the trans to the cooler and running about 14 quarts of transmission fluid through it to flush the torque converter because mine doesn't have a drain plug. It's been working perfect for ~60k since. Another issue that can be a possibility is coolant getting into the transmission fluid because of a leak that occurs within the radiator between the coolant and trans cooler. There is a kit to test the transmission fluid for glycol contamination at the dealer. I forget if it is the Bosch or Valeo one that has issues.
 

·
Immoderately Caffeinated/ Vintage Moderator
Joined
·
16,392 Posts
Discussion Starter #8
I had a similar issue (only in forward direction) where the car would take off from a stop poorly then feel like it "shifted" somewhat harshly and continue on normally. No codes or suspect shift adaptation values with the SDS. The issue was the torque converter lockup clutch. I ended up replacing the torque converter solenoid on the valve body and disconnecting the output line on the trans to the cooler and running about 14 quarts of transmission fluid through it to flush the torque converter because mine doesn't have a drain plug. It's been working perfect for ~60k since. Another issue that can be a possibility is coolant getting into the transmission fluid because of a leak that occurs within the radiator between the coolant and trans cooler. There is a kit to test the transmission fluid for glycol contamination at the dealer. I forget if it is the Bosch or Valeo one that has issues.
The trans was done in 2013 though with less than 50k now. They did the torque converter and the fluid was given the all clear by my indy last week.

I don't know how long it takes for Nulon to work or if it works at all but the next day the rotten thing started and drove perfectly.

Tomorrow it will be two days since started so will see what happens. I can only think its a sticky valve which is initially preventing the torque converter from filling. If that's even possible?
 

·
Immoderately Caffeinated/ Vintage Moderator
Joined
·
16,392 Posts
Discussion Starter #9
You have the 722.6 right? Have you checked the fluid level with an MB dip stick. A140589152100
Yeah, done all that. Will report back tomorrow.
 

·
Immoderately Caffeinated/ Vintage Moderator
Joined
·
16,392 Posts
Discussion Starter #10
Okay, nearly three days without starting and today no issues at all on cold start.
 

·
Immoderately Caffeinated/ Vintage Moderator
Joined
·
16,392 Posts
Discussion Starter #11
Another couple of cold starts and no issues. If it's good behavior is due to the Nulon additive then I'm going to start chugging it myself instead of beer.. 🍻
 

·
Registered
Joined
·
6 Posts
Tomorrow it will be two days since started so will see what happens. I can only think its a sticky valve which is initially preventing the torque converter from filling. If that's even possible?
The valve for the torque converter is only controlling the lockup clutch. Torque converter lockup clutch issues can feel like a slipping gear, harsh shift, or shuddering. If it seems like the additive works I'd just keep driving it and see what happens before worrying too much.
 

·
Immoderately Caffeinated/ Vintage Moderator
Joined
·
16,392 Posts
Discussion Starter #13
Thanks! Does that mean the TC doesn't or shouldn't drain into the pan overnight?
 
1 - 14 of 14 Posts
Top