W124 300D Auto no forward gears

[roadhog]

Hi all, as above.
I was driving along at 30ish, noticed the revs hunting. I stopped, tried to move off again but nothing happened until approx. 4k. Above that the car sort of shuddered off. Reverse seems to work, I can feel it engaging but none of the forward gears do now.
It might be worth mentioning that I had my atf changed last Friday (by a reputable indie). I checked the level when this happened yesterday and it seemed fine. Any ideas?

 

[Richard Moakes]

It might be worth mentioning that I had my atf changed last Friday (by a reputable indie). I checked the level when this happened yesterday and it seemed fine. Any ideas?

The two events may be connected, its worth having it taken back to there for an initial check I would think.

 

[roadhog]

That's where the car is now but they've not had time to investigate yet.
I too think that the two events are connected, it would be a bit much of a coincidence. But stranger things have happened.
I was just wondering if someone on here knew of a probable cause for having no forward drive when reverse appears to be working.

 

[Bolide]

There's a forward / reverse selector gear thingo (that's the technical description) that can fail. It is replaceable but it's a box-out job

Or maybe dropping the oil pan has disturbed gunk that's got into the valve bodies?

Nick Froome
www.w124.co.uk

 

[television]

I will also say dirt in the valve block, sump of it it can be taken off and cleaned

 

[roadhog]

My initial thoughts were also that some muck might have gotten into somewhere when the sump was off. I phoned the garage and was told that they'd had a look at the box and couldn't see anything wrong. He said they would have to speak to a gearbox specialist. From the tone of the conversation I got the impression that was as much as was going to be done. Now what?
Can someone elaborate on this valve block thingy please?
I'm beginning to think I should have left the box well alone, especially as I just wanted the oil changed as a precaution (car newish to me, not sure when last changed etc) and it was working fine prior to this. I must admit that subjectively I thought the gear changes were a bit smoother after the atf change and I was very pleased right up to the moment when the car coasted to a halt...

 

[television]

The sump has to come off again and the valve block can be seen and taken off.

when the fluid is drained its important to keep it clean, as what comes out in the fluid tells so much about the problem.

Are you going to do it your self

 

[Richard Moakes]

PM me your email address, I will send you a 722 series transmission guide pdf file, it might scare you, but it will show you what is inside the box.

It could be the valve block, but it could also be the B2 piston http://dieselgiant.com/Mercedesb2pistonsealreplacementl.htm

Good Luck

 

[roadhog]

Thanks for that guys.

Malcolm, I may have to. Especially as I've broken the Volvo yesterday but that's in Belgium and another story altogether.
As for keeping the fluid clean, I'll be changing it again if I do end up doing this job. I'm guessing the garage had the sump off yesterday unless they only looked at the box from the outside?
The funny thing is, I only outsourced the job in the first place because it seemed too much of a pita. Now it looks like I'll be operating myself after all. Doh!

Richard, you have a pm. Thanks in advance, I'm already bricking myself in anticipation of the horrors awaiting me.

I won't be back in the UK until Tuesday so not much will get done before then but keep an eye out for the inevitable "Help me get my gearbox back together" thread.

 

[roadhog]

Update!

Well, I spoke to the garage today who informed me that they had spoken to the gearbox specialist they use. Apparently he's diagnosed (over the phone) that my problem is "the forward band has gone" and it'll be £750 plus the dreaded to fix! Plus, obviously really, the cost of having my car transported to them.
More crucially, he's absolved the garage of all blame (which I was never going to be able prove anyway) and it's nothing at all to do with the fluid change carried out some 80 odd miles prior to the event. Apparently, the forward band (?) 'goes' a lot on these cars and it just happens.
Coincidence right? :roll:
I'm no specialist of course but I've decided (with the aid of Richard's excellent info) that the valve body assy is a better place to start. It's not as if I've got much to lose. Let's hope the weather is kind to me next week