A box full of neutrals

[Pitts Pilot]

I’ve got 2 problems with the 7g (722.9) automatic transmission on my 2008 R230 SL

First, it has jerkiness in the first two gears when cold. It grabs a gear and you lurch forward (or backward).

It’s fine after a few minutes, but from cold it’s a kangaroo!


Second, again from cold, every, say, fortnight it gives me a box full of neutrals instead of Drive or Reverse. I just sit there having engaged Drive and can freely rev the engine without any forward movement. This issue started about 3 months ago.


The first problem has no DIY solution. The second means ‘key out’ and start again. It can take up to 4 attempts to get the box to engage a gear, so that’s a lot of starting and switching off, but I get a gear in the end and off I go.

Both happen when the box is cold.

Mileage is 38K and I've just had a B service at MB Basingstoke, including a transmission oil change. I discussed the ‘box of neutrals’ problem with them, and they said their Star machine had found 2 error codes for ‘Low Voltage’.
I can account for these occasions – a flat battery after 4 weeks non use, and configuring the Sat Nav for 1.5 hours without switching the engine on

So I thought that all was explained and was well……



It happened again today. I drove the car yesterday, everything was fine. This morning I couldn't find a gear (it took a single ‘Key out’ and re-start to be on my way, this time…).


I’m booking the car into Wandsworth MB (because they are around the corner from me, versus Basingstoke who I bought it from, next Monday.

How shall I approach this problem with MB? Odds on the ‘neutrals’ won’t occur in their stewardship, so how do I convince them something is wrong?


If I’m lucky today’s ‘neutrals’ might have flagged up a more serious error – like a solenoid or speed sensor in the Value Unit, but I’m not usually that lucky! (And it didn't before).

It’s £1,400 to overhaul the Valve Unit, and ideally I’d like it done under warranty!!


Has anyone any experience of these problems? I suspect the two are related. What do you think?

Many thanks
Robert

 

[Giantvanman]

How shall I approach this problem with MB? Odds on the ‘neutrals’ won’t occur in their stewardship, so how do I convince them something is wrong?

Run a video from when you open the car and throughout?

 

[Pitts Pilot]

Run a video from when you open the car and throughout?

Yes, that's a good idea. Got the 'phone at the ready...!


Cheers,
Robert

 

[Pitts Pilot]

Run a video from when you open the car and throughout?

Just tried it. Started fine THIS time!!

Robert

 

[Pitts Pilot]

Any thoughts as to what is wrong?


Thanks,

Robert

 

[Giantvanman]

Typical; these things never play fair to order. As for what it is, my guess would be either a linkage problem or a sensor issue………my money would be on the latter as I vaguely remember a similar issue that was raised some time back. I THINK it is something to do with the gearbox control unit not being told that it is okay to engage drive, either by a sensor in the selector or from the brake pedal.

I apologise if this in completely wrong and for my poor memory retrieval skills.

 

[C43AMG]

Robert, have you used Wandsworth MB before ? If not they haven't got the best customer service record. I would make a point of seeing the Service Manager, start from the top.

 

[Pitts Pilot]

Robert, have you used Wandsworth MB before ? If not they haven't got the best customer service record. I would make a point of seeing the Service Manager, start from the top.

Thanks Peter

I've used MB Wandsworth a dozen times before, and Yes, I did 'blast' them once for poor customer service (and the guy concerned left 2 weeks later...), but on the whole my experience has been a good one.

I'll let you know how I get on.


In the meanwhile I'm video-ing every start up hoping the box will fail. How weird is that? (!)

Thanks for the heads-up

Robert

 

[BlackC55]

It sounds like the fluid level is low.

 

[C43AMG]

That's good news, maybe they have got there act together now. It's just I have had a few colleagues use them in the past, never again.

 

[Pitts Pilot]

It sounds like the fluid level is low.

The problem existed before the B service, at which time the oil was changed - so new fluid level, and the problem has reoccurred ONCE since.

MB Basingstoke were quite particular about the gearbox fluid (or so it seemed to me). I had driven up from London that morning and the car went straight into the workshop when I arrived.

However, they later parked it on the forecourt for an hour, saying the 'box was too hot to do the oil change and I would have to wait....

So two levels. What's the chance of both being wrong?

The whole thing has got me quite concerned if I'm honest!

Cheers,
Robert

 

[Pitts Pilot]

That's good news, maybe they have got there act together now. It's just I have had a few colleagues use them in the past, never again.

The guy who was fired (probably a couple of years ago) promised to call me and didn't, but the incident that might have sealed his fate (you never know what goes on...) was when I delivered the car to them early one morning only to pitch up (of my own accord- no phone call ) at 4pm to discover it had not moved from the spot I had parked it

I was furious! And decided to 'make an issue of it' and complained bitterly that they were wasting my time.

There have been some excellent guys doing the customer 'liaison' job since.
Currently there is a gay guy (who's name I cannot remember) who is totally brilliant. He's a joy to deal with; he similes at you, he phones you back when he promises, he's efficient, he seems genuinely pleased to see you and keeps you informed of what's going on, he cannot be helpful enough, etc, etc.

Their servicing/hands on car seem to be OK too.

I checked a couple of months ago when I was there having a seat recovered under warranty, he's NOT intending to go anywhere


As we all know, it's about the people, and right now MB Wandsworth seem to be doing an above average job, (and I'm very un-English about these things: I'm not shy to complain or praise, whatever is due!)

Cheers,
Robert

 

[C43AMG]

That's very good news, good to hear.

 

[Pitts Pilot]

Damn, blast, etc, etc

Damn, blast, f@@k, you barst@@d

The car was in MB Wandsworth today, and they found nothing wrong with the gearbox

Not a single fault code was found, it is, by every measure they have, in perfect working order!

Yet 7 days ago, after a B service and gearbox oil change, it give me neutrals again instead of Drive.


This is really frustrating. The flipping car has been teasing me for 3 months now, and I don't like it one bit.


I have agreed with MB Wandsworth that I will video the problem when it occurs. This is straightforward as I carry a smartphone...


The service rep agreed with me that it was probably an intermittent fault with the valve unit that controls the gear changes, but without so much as an error code I do not have a chance for a warranty claim; no chance at all

As for said absence of a fault code on the Star machine (I saw a copy of the readout), I am mystified.


So, I wait and present video evidence, but even then, I'm told, the MB warranty people will need much more, such as diagnostic evidence.



What makes a gearbox decide one morning its going to give you neutrals rather than a gear, on startup?


Hey-ho, I'll have to live with the problem for now....


Damn, blast, etc, etc,

Robert

 

[BlackC55]

I'd put good money on the fluid level being low.

 

[BlackC55]

Let me check it foc.

 

[Mercedes man]

Hi had this on customers s class 7 g was axilary battery u/s.took a while to find but this was probelm every morning car would start drive a few hundred yards and then box of neutrals

 

[Pitts Pilot]

It sounds like the fluid level is low.

I think I might owe Olly an apology

I just spoke to GNN Motors in sunny California. GNN repair MB 7g transmission valve units and will ship them anywhere in the world.

Check out their site G&N Motors | Mercedes Service & Repair Center


Anyway, I had a chat with a guy there and asked if he had ever heard of 'a box full of neutrals' and he replied that he had, and it was usually due to low transmission fluid.



So what are the chances of having low fluid level, then doing a B service where the oil is changed, and STILL having a low fluid level?

Well, fairly high it would seem!


He said that the fluid level must be measured when the oil is at 43 C.

So as my car is going to PCS on Friday to have a Renntech Lowering Module fitted, I'll ask if they could double check the transmission oil level..... (at 43 degrees C).


Sorry, Olly


Cheers,
Robert

 

[Pitts Pilot]

Hi had this on customers s class 7 g was axilary battery u/s.took a while to find but this was problem every morning car would start drive a few hundred yards and then box of neutrals

Had the rear battery on a professional battery tester and the read-out was fine...battery in good condition.

One to watch though - thanks


Cheers,
Robert