TundraRoads

When driving it will slip. The engine is still running fine but you can feel slippage in the transmission—the car will loose momentum. Pulled in to a parking lot and slipping seemed worse. Pulled in to a space but when I put it in reverse to back up a bit there was nothing there. Engine rev'd but car seemed to be in neutral even though it indicated reverse. Shifted to D and similar though would move forward slowly with lots of rev's. Back in reverse again and more similar to D, not really gripping but a lot of rev's would get it to move slowly.

Had it towed to our dealer last Fri. As of today they say they see it doing the same things but after 3 days of work can't figure out why.

This is my wife's car that she drives quite gently and has had all service by local dealer since we purchased new. It's never towed anything nor carried extensive weight. No reason for stress on the transmission.

This seems like a different issue than experienced by the diesels or than mentioned here: https://mbworld.org/forums/new-m-cla...n-problem.html or the one here (https://mbworld.org/forums/new-m-cla...sion-slip.html) that seems to be somewhat consistent with higher speed passes. Also just found this: https://mbworld.org/forums/new-m-cla...er-denial.html

pcy

STAR diagnostics should reveal error codes. Dealer should be able to pull those codes.

TundraRoads

They said the codes aren't telling them anything so they've been talking to Chicago and Germany.

peter2772000

How many miles on her? Change the transmission oil?

TundraRoads

About 58k miles IIRC. All maintenance has been performed by the dealer on schedule.

peter2772000

That's nothing, bloody shame. And even if they didn't change the tranny oil, which I'm sure they don't do.

TundraRoads

When the service guy first called after it'd been towed in and they'd had it in the shop for a day he asked when the last time the xmission fluid had been changed. Strange question coming from the place that has done all of the maintenance on it. We have all of the service invoices and none seem to indicate a xmission fluid change. Both the A & B services list the oil filter & oil separately as well as fuel additive, dust filter, washer fluid, etc. No mention of xmission fluid or filter anywhere that I can tell.

So, should it be listed separately or is it hidden in the 'PERFORM B-SERVICE AND TEST DRIVE'?

Any idea what it will say?

Thanks,

pcy

Transmission service (fluid and filter change) will be explicitly listed in the receipt, if that was done.

pgeller

A transmission flush with new fluid and filter should set you back a few hundred bucks at the dealer. I did mine at 40k miles and the fluid was very grungy. If the filter is clogged then shifting will be slow and slippage can occur. The various clutches and friction materials in a modern tranny do pollute the oil. Mercedes likes you to think this stuff lasts forever. Slow driving in town would be worse than spirited driving on open roads.

Just my humble opinion. Good luck.

pg

peter2772000

Wow, really? $40k miles and the oil was grungy? Do you do any towing, anything that could explain the "grunginess"?

My FJ Cruisers oil was blacker than the ace of spades at 60k miles, but Toyota autos' are known for that, mostly due to the oil they use. I did a complete flush at home, was easier than you'd think. No dipstick either, you have to check the level thru a port in the tranny case at 105*F. If your oil was in bad shape at 40k miles, then I think I'll be proactive and replace ours this summer, we're at around 15k miles.

To the OP, sorry for hijacking the thread. To be honest, I don't think an oil change will fix your issues, sounds more serious than a dirty filter and yucky oil