C63 Delayed gear change

[TomC63]

Hi all, I’m new to the forum.

I have a 2012 C63, currently having an issue with gear change.
The car will deselect the gear instantly but will not engage the new gear for a few seconds. It does this in all modes and also when selecting reverse. Servicing is up to date and there are no fault codes. Please help!

 

[onefortheroad]

Any engine fault codes ?

 

[TomC63]

Any engine fault codes ?

No nothing. I’ve scanned with my Mercedes specific reader and nothing. When viewing live data it clearly shows the delay between selected gear and actual gear.

 

[Uncle Benz]

I would be checking the fluid level first, and looking for any obvious leaks too. Slow changes are most often down to a low fluid level

 

[TomC63]

Thanks. This was my thought too, so I bought 1litre of gear oil and attempted to check level earlier, unexpectedly when I removed the sump plug lots of oil began to flow out. I’m worried the oil level pipe has been broken off inside the sump…

 

[Uncle Benz]

The level is set via the standpipe, as you seem to know. You need to have the engine running while checking the level, and the oil must be circa 40 degrees centigrade

 

[TomC63]

I presumed you’d overfill the gearbox whilst cold then as you said, set the level at 45degrees by removing the sump plug and allowing to drain to the pipe level?

 

[Uncle Benz]

I presumed you’d overfill the gearbox whilst cold then as you said, set the level at 45degrees by removing the sump plug and allowing to drain to the pipe level?

Yes, that’s how we do it when carrying out a fluid and filter change. The tool I have we leave connected while running the engine and warming it up. As it approaches the temperature we pump a little more in and then allow it to spit back out to get the level spot on. It’s an experience thing. I’ve done hundreds!

 

[TomC63]

Thanks very much, I’ll try again tomorrow. Surely you wouldn’t expect a lot of oil to come out when removing the plug whilst cold would you?

 

[Uncle Benz]

If the engine wasn’t running, then yes, a lot will come out. With the engine running the pump lifts oil from the transmission sump and keeps the valve body filled up. It’s a litre or so I would think

 

[Uncle Benz]

If you had the engine running and a lot came out either it’s overfilled (unlikely) or the standpipe has become dislodged

 

[TomC63]

No the engine wasn’t running, my first time doing one of these . I captured the oil in a clean container so I’ll pump it back in with some fresh

 

[Uncle Benz]

That’s your mistake right there. It’s now definitely low on fluid

No the engine wasn’t running, my first time doing one of these . I captured the oil in a clean container so I’ll pump it back in with some fresh

 

[TomC63]

I’ve managed to set the oil level right and unfortunately it hasn’t made any difference. Any other ideas or would a trip to the MB specialist be right?

 

[Uncle Benz]

The next thing I’d be doing is dropping the pan to have a look at the condition of the filter and see if any debris in the pan or on the magnets

 

[zedmeister]

I think there is a program on star to test the gearbox. Best to do that first. You say that servicing is up to date but how long ago and how many miles ago was the gearbox serviced? A lot of places just don't do the gearbox. Is it also delaying with the paddle shift?

 

[TomC63]

I aren’t exactly sure on details without looking but I know it’s well within the service interval. Looks like I’ll leave it for now until it’s back on the road and get it plugged into star. I don’t really want to drop the sump and have to buy a full service kit and it maybe not solve the issue. Thanks for your input guys, much appreciated

 

[TomC63]

Yes the delay is still there in manual, up and down shifts

 

[Uncle Benz]

just for some background, did the car suddenly start doing this, or has it got worse over time?

 

[TomC63]

It has got worse, first noticed a delay when shifting from park into reverse, then drive. Now it’s right through the box. It’s horrendous because the car goes into a false neutral between shifts so revs, then bangs into the next gear.