What to expect from a 7G+ transmission?

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molgrips

Active Member
Joined
Jul 26, 2021
Messages
105
Location
Cardiff
Car
CLS 250
Forgive me if this is already covered but I've searched a lot and this is all rather specific. As per my other thread I've recently got a 2013 CLS 250 with 86k miles, and I'm not sure if it's got transmission problems, or will do soon. I was expecting a Mercedes to be very smooth and it's not.

  1. There's a pause in power when accelerating normally as it shifts. To me this feels like an adaptation to take some other issue into account. Is this normal?
  2. When downshifting manually (in manual mode) at constant speed, not only is it really slow but there's some odd behaviour. The rev needle climbs a bit, then pauses, then climbs to the required speed. It's as if it's hunting for some kind of bite point. Is this also normal?
  3. The most concerning is the rattle when moving from P or N to D or R. You can feel the transmission grab and then there's a definite rattle. It does it when warm.
I only bought the car three weeks ago so if there's a real issue I can in theory try and return it. However it's at the point where to me, it indicates there might be a problem but the dealer will easily shrug it off. So the question is, do any of you recognise these characteristics?
 
Difficult to be sure about points 1 & 2 without driving the car, but #3 is definitely indicative of an issue.
 
My E250 was much smoother shifting after i had the trans fluid changed so it could be worth seeing if yours has been done. Mine also had a software update which also improved things. When warm the changes are almost imperceptible, a bit more noticeable when cold. Since the software update mine also seems smoother in S rather than E.

The rattle/grab could be engine/transmission mounts? I had mine changed at 90k and it transformed the whole car, including making the gear changes much smoother. Can you feel any vibration coming through the transmission tunnel inside the car? Before i had mine changed i could definitely feel a vibration which disappeared completely after all the mounts were changed. I think this is an easier way of assessing the condition of the mounts rather than the trick of putting it in drive and holding on the brake to see if the engine moves when you rev it slightly.
 
I took it to a local place (A1 diagnostics in Cardiff - it is also booked at Continental Cars on Friday) using an Autologic machine and they said it didn't come up with any software updates or codes related to transmission directly, although there were ABS implausible signals from all four wheel sensors which were cleared and didn't return.

Transmission fluid was changed 30 k miles and 2.5 years ago at a dealer, according to the service report.

Engine mounts are a distinct possibility. Can I feel vibration? Well again, I don't quite know what to expect, but overall the car isn't particularly smooth in general. It's certainly not filling me with a lovely 'ooh Mercedes' feeling. Once it's in D or R when stationary, it does vibrate a bit.
 
The ATF change on your 2013 car was first due in 2018, so the car seems to have been serviced correctly. It will next be due in 2023 (assuming the annual mileage remain average or below).

If you bought the car from a trader (i.e. not a private sale), I would try raising this with the selling dealer first, especially point no. 3.
 
I took it to a local place (A1 diagnostics in Cardiff - it is also booked at Continental Cars on Friday) using an Autologic machine and they said it didn't come up with any software updates or codes related to transmission directly, although there were ABS implausible signals from all four wheel sensors which were cleared and didn't return.

Transmission fluid was changed 30 k miles and 2.5 years ago at a dealer, according to the service report.

Engine mounts are a distinct possibility. Can I feel vibration? Well again, I don't quite know what to expect, but overall the car isn't particularly smooth in general. It's certainly not filling me with a lovely 'ooh Mercedes' feeling. Once it's in D or R when stationary, it does vibrate a bit.
When i bought mine i was in a similar position - i didn't really have anything to compare it to (in terms of engine/trans mounts at least). It was only when i used a W212 as a loan car as mine was being serviced i realised all my mounts were completely shot. This despite a full AA inspection! So if you put your hand on the transmission tunnel inside the car near where your knee is you should be able to feel the very slightest vibration, but very slight, almost nothing. Anything more obvious and it would suggest the mounts are cooked. It's tricky because i guess the mounts gradually fail and get progressively worse, so a sliding scale rather than an obvious good/bad. When i had mine changed - it wasn't that expensive for the engine and trans mounts, i was surprised how much nicer the gear change was as well as the general smoothness and quietness of the car.
 
I can see two engine mounts from the top. With the bonnet up I had my 'assistant' put the car into drive then park repeatedly. The engine shifts clockwise and I can see the nearside mount compress by about 2-3cm and the offside one go up a similar amount. They compress immediately and there's no apparent movement with the vibration which does suggest they're shot - it looks like they flatten straight away and they there's no more shock absorption movement left.

With the car in drive but stopped I can feel vibration through the steering wheel and I can see it.
 
Engine and gearbox mounts would be an easy first step, my 7g is now over 100k and touch wood very nice.
I did my rear gearbox mount s few months ago and I immediately noticed a much tighter nicer feel to changes and acceleration and deceleration.
 
I can see two engine mounts from the top. With the bonnet up I had my 'assistant' put the car into drive then park repeatedly. The engine shifts clockwise and I can see the nearside mount compress by about 2-3cm and the offside one go up a similar amount. They compress immediately and there's no apparent movement with the vibration which does suggest they're shot - it looks like they flatten straight away and they there's no more shock absorption movement left.

With the car in drive but stopped I can feel vibration through the steering wheel and I can see it.
Yes they definitely sound like they're shot. From what i read they can fail from about 50k miles.
 
How many are there? I can see two for the engine, presumably there are some for the transmission too?
 
You should really look for a STAR diagnosis, anything really wrong with your trans will show up.
 
How many are there? I can see two for the engine, presumably there are some for the transmission too?
From memory i think there are two for the engine and one for the transmission. It was a few hundred to get them all changed - the best money i've spent on mine for sure!
 
I did the test where I had someone try to drive off with the brakes on, and the engine didn't seem to move unusually, not like in the YouTube videos. So any mechanic doing the same test will conclude the mounts are fine.

It's continuing to improve when driving now, not sure why exactly. But the clunk when shifting from P or N to D or R is pretty bad and if anything is getting worse. It could be that the clutch is engaged too hard when in drive with the brake pedal pressed.
 
Hi , you can buy them yourself (and change them yourself if you are even half handy with a spanner) They are not expensive , Lemforder is the name most go for as they are one of the suppliers to Mercedes Benz.


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Let us know how you get on :thumb:
 
Good couple of videos, but that top one ain't 'arf making some horrible noises !
 
Spoke to the fantastic people at Continental Cars of Cardiff. I hate garages generally but they were great - he was happy to talk tech with me and was very knowledgeable indeed, so thumbs up.

He concluded there's actually nothing at all wrong with my car, in fact remarkably so - but there were two problems - one is the NOx update which has cost smoothness, response and economy; and the other is down to me. I'd been booting the car about a bit in various modes which seems to have confused the adaptation. I need to be careful to keep any booting to S or M mode and general sensible driving to E mode, because each mode has different adaptations. So if you rev it up in E mode it'll then be worse for normal driving.

On the one hand it's a shame that the NOx update has made it worse but on the other at least it's not actually a fault and I can relax! The D/R clunk is still there but it's got a bit better now so who knows, perhaps that's just how they are, perhaps it'll improve.
 
Spoke to the fantastic people at Continental Cars of Cardiff. I hate garages generally but they were great - he was happy to talk tech with me and was very knowledgeable indeed, so thumbs up.

He concluded there's actually nothing at all wrong with my car, in fact remarkably so - but there were two problems - one is the NOx update which has cost smoothness, response and economy; and the other is down to me. I'd been booting the car about a bit in various modes which seems to have confused the adaptation. I need to be careful to keep any booting to S or M mode and general sensible driving to E mode, because each mode has different adaptations. So if you rev it up in E mode it'll then be worse for normal driving.

On the one hand it's a shame that the NOx update has made it worse but on the other at least it's not actually a fault and I can relax! The D/R clunk is still there but it's got a bit better now so who knows, perhaps that's just how they are, perhaps it'll improve.

Matt looks after my CLS and Mrs jdrrco's W202 and he's very good at his job. Stick with him.
 

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