CLK430 gearbox not shifting

[Senator]

My CLK430's gearbox has decided to stop shifting gear properly. I can select drive and reverse, but there's a bit of a jolt when selecting, and then it seems to be stuck in 1st and I can't manually select any gears either. I assume this is some kind of 'limp home mode'?

I first noticed it last week, and after a switch off / re-start it was back to normal, but this weekend it was doing the same again so needs further investigation. I've done some googling and the first step is to check the oil level. Are the cheapo dipsticks up to the job or do I need to stick with a known brand? Also I've seen some guides say the car should drive or reverse when checking, others say neutral. Is there a definitive guide on how to do this properly?

Thanks

 

[noogieman]

Sometimes brake light switch breaks down and the car wouldn't shift properly?!
This is a common problem.
Do you have working brake lights?

What year is your car?

 

[Petrol Pete]

When was the gearbox last serviced and what mileage is on the car ?

 

[Senator]

Do you have working brake lights?
What year is your car?

I'll check the brake lights this evening. The car is year 2000.

When was the gearbox last serviced and what mileage is on the car ?

Mileage is around 114k, I don't know if/when it was last serviced. Is there a recommended interval or is it supposedly a 'sealed for life' unit?

 

[Petrol Pete]

Sealed for life is a myth. Plenty info online and on this forum '722.6 transmission service' . I would recommend a full gearbox service , expect to pay between £275 & £350 depending on where you live and where your nearest MB independent specialist is.

If you can get a good result from the dipstick then well done , it's a bit of a faff and at the end of it you might add one litre of good ATF to 8 litres of ancient crap fluid in the box.

A service is what it needs.

 

[Jobsworth]

Check the level in neutral with the engine idling. If it was clearing with a key cycle it's likely an electronic fault though. A code read will be the next step.

 

[Senator]

So the brake lights are working fine, next I have a dipstick on it's way so will check that in the next couple of days. I'm happy to get it booked in for proper check over and oil service, I just don't fancy the 20 mile drive to PCS in limp mode!

 

[Senator]

I tried checking the gearbox oil level today, but struggled making sense of the reading. I intend to take it to a Merc specialist but it's going to be a real pain getting there at 20mph all the way, so I was hoping to see a low fluid level - meaning I could top it up to get out of limp mode and drive it to a specialist for a full check up and fluid change.

I had the car running for over 30mins, mostly idling on the drive but I did include a short run down the road in limp mode. I kept the engine running, selector in P, gave it a few minutes after the run for things to settle and if anything the reading looks overfilled to me. I assume I followed the procedure correctly but if anyone can tell me I've done it wrong please let me know!

 

[Wearsthefoxhat]

It does indeed look to be over filled. Was the car on level ground too ??.

 

[Jobsworth]

I does appear to be overfilled, but unless you have added oil unnecessarily it doesn’t fit with the fault you described. It needs a read of the fault codes. My money is on a speed sensor fault on the electroplate. I’ve done two this week on 722.6. £390 all in with new fluid and filter too. These cars have never been so cheap for parts!

 

[Senator]

Thanks for your replies, yes it was on level ground and no oil has been added. Looks like I'll be taking a painfully slow drive to get it checked properly!

 

[DSM10000]

Do you have break down cover with recovery?

 

[Senator]

Yes, but not sure it would cover this situation

 

[DSM10000]

Yes, but not sure it would cover this situation

Might be worth asking. It is not driveable and some policies cover this.

 

[Petrol Pete]

If you have recovery on your breakdown cover , plan well , drive a mile away from home call in as a breakdown and ask for it to be recovered to PCS. Or pop it on a low loader. No where near you but my mate would do a 20 mile lift on his truck for £40 cash on a quiet day.

 

[Martin 1]

First, to check the level, after a run, move the selector slowly through each position and back to park, then check the level with the engine idling, that should give you an accurate level. What colour is the oil ? if brown and a bit of a burnt smell, get it changed urgently, if red/pink it's OK. Most importantly, check the level as I suggest. Good luck.

 

[Weldfixfab]

I had a simular problem in my cls 55 amg turned out to be be gear selector solonid not cheap to sort it hope this my help