W219 CLS with 7G gearbox - cost of oil change?

[Wighty]

Yep,


I’ve already contacted Star, hopefully should get a quote from him soon.

Let us know how it goes .

 

[Peter C1974]

Hmm. The last two mornings the hard downchange has not occurred at the end of my road. I have changed the gearbox setting to Sport - would this make any difference or has something else changed (fixed itself!)?

 

[Steve@Avantgarde]

Nothing fixes itself!

 

[EmilysDad]

Nothing fixes itself!

We all live in hope ..... I've a few things around the house that need fixing

 

[Wighty]

Nothing fixes itself!

What about a robot , I bet that could fix itself

 

[steveq]

The human body does and indeed most of creation does -- up to certain limits, of course.

 

[Larkone]

In IT we have the magic invisible pixies that always fix faults just before the technician turns up.

 

[Peter C1974]

Same again this morning, no hard downshift at the end of my road.

There is something that I am doing differently. Where as before I would barely touch the accelerator and almost coast up the road, the past few days I’ve been accelerating (gently) causing the transmission to select gears more quickly (whilst coasting the changes were slow).

Looks like the transmission needs less gentle treatment for it to work gently!

 

[Wighty]

Same again this morning, no hard downshift at the end of my road.

There is something that I am doing differently. Where as before I would barely touch the accelerator and almost coast up the road, the past few days I’ve been accelerating (gently) causing the transmission to select gears more quickly (whilst coasting the changes were slow).

Looks like the transmission needs less gentle treatment for it to work gently!

Good to hear about the shifting . You may even be able to talk yourself out of getting the ATF/filter change being done at all .

 

[Botus]

did anyone mention cold start..

idle might be up to cope with enrichment for a bit,
to get the Cat hot many autos hold back on gear changes to force revs up and to increase exhaust gas speed / temp.
some will stop the first change happening till x revs, others for x amount of distance, this feature comes and goes to some extent with ambient air temp (so if cold one morning and mild the next might not happen etc.)

the other point you do have a sport / comfort switch ? most do and this alters behaviour of the box and indeed which gear it drives off down the road in.


as an aside mine is currently in sport

first few changes the other day were, rough / nasty / rough / ****** hell.... then I stopped noticing

 

[Peter C1974]

Another update:

Gearbox behaved itself again this morning at the end of my street - no hard downshift. Not sure whether the issue is related to engine speed, I will keep an eye on the tacho in the future.

Another symptom:

Pulling onto a motorway, if I accelerate very gently, the gearbox will not slip into 7th gear at 70MPH unless I give the accelerator a good prod. If I don't, the gearbox will hold 6th gear apparently indefinitely. However, if I accelerate a little quicker, then the gearbox will change up into top below 60MPH.

I think that an oil change would be a good idea. Hitherto I have not heard back from Star.

 

[Botus]

how do you know its 6th 7th change....

for last 15 to 20 years TC lock up has been in place to add to the efficiency of auto boxes,
in normal mode the drive on a convention "slush box" auto is exclusively by transmission fluid being flung around the torque convertor, with an efficiency of between 0% (which is why you can stop at the lights and the engine keeps going) and a max of around 98%

this 2% loss costs money, performance and emissions. to resolve an electromagnetic clutch can lock up the TC under certain conditions... steady throttle, constant speed, lower power situations... as soon as you are on off the brakes, accelerating, or changing gear it drops out... the TC lock up can be seen on the rev counter and felt in light throttle conditions as if another gear change

I suspect what you think is a gear change is the TC lock up clutch coming in, if you are booting it will either not happen or come in later as you back off a bit

these go wrong on Mercedes more than I have ever heard on any other car.... in fact NEVER heard of it till I started reading this forum...

 

[Peter C1974]

Botus,

Unless activation of the torque converter lock up reduces engine speed by approx 1,000 rev/min whilst the car is traveling at 70MPH then I’m certain that the reported issue relates to the 6th-7th gear change.

Torque converter lock up does not reduce gearing!

Peter

 

[star]

My apologies, will do it this eve.

 

[Botus]

Botus,

Torque converter lock up does not reduce gearing!

Peter

no of course can't change gearing, but the effect is very similar. Your issue when I re read, sounds back to front by the way (for the TC clutch) but it may be a fault here that's causing your box to not change correctly

the very best a non lock up TC can give is 98% efficiency (drive) under perfect conditions. on lower throttle, old oil, slight worn gearbox, it will it will give less, of course up to 100% slip. So at the point we are discussing, a TC might be operating around 85% efficiency so as the lock up clutch comes in you get a magic drop in revs of maybe 15%

on my old omega (4 speed TC lock up in 3 and 4th) in top, software stopped from locking unless speed above 49mph and it feels exactly like another gear change and the revs drop 400 to 500 rpm

 

[Stevetaxi]

MB service kit for 722.9g is £114 inc vat+postage

 

[Peter C1974]

Oil changed this morning, thank you Ian. £209 inc VAT, job done.

I will update this post again in a couple of days once I've had the chance to drive the car from cold.

 

[Wighty]

Oil changed this morning, thank you Ian. £209 inc VAT, job done.

I will update this post again in a couple of days once I've had the chance to drive the car from cold.

Good job Peter and that's a nice price

 

[Botus]

from longevity perspective an oil change is essential, so well worth doing it. will be interesting to hear of your thoughts on the change quality over the next few weeks.

I though it was nicer for a few days but soon noticed was just as rubbish as before

 

[Naraic]

Yep 7g isn't that smooth. I find in stop/start it's better to be in C than S so you don't get that harsh downshift into 1st as you are coming to a halt.

I await your report re the oil change.