S430 auto box 'slipping' ?

[Cool Mart]

Last couple of days I've noticed the revs increase between gear changes, and reading through this forum have seen a few similar problems, but nothing exactly the same so I thought I'd post and see if anyone had any ideas.

By the speed I'm doing I'd guess the change was between 3rd and 2nd. I put my heavy foot down and it disengages 3rd, the revs rise about 2000 rpm and then 2nd engages with a jolt. I have noticed a few other sluggish changes recently but as this is the first auto I've driven for quite a while and I put that down to my hesitant foot tickling a kick down switch at the moment of change.

MAS/MAF comes up in similar threads but I'm not sure of the connection between airflow and gear selection.

What do you think ?

 

[frog1520]

MAF can definitely affect the gear changes. When my MAF is knackered
the gear changes are crap!

How many miles on it? When was the ATF last changed? Changing the
ATF made my changes much smoother, so that might be an idea if the
MAF doesnt fix it!

 

[Cool Mart]

Car's done 101,000, no idea if the MAF has ever been changed.

Martin

 

[Birdman]

I had 'flaring' on the 1/2 upchange on a 5-speed autobox and it required new clutches. Hope it's the air mass sensor or ATF as they're cheaper problems to fix. Btw you can source the OEM Bosch part for much less than the MB price. But it needs the fault codes reading.

 

[Cool Mart]

Oooo, don't like the sound of that ... how much did it cost if you don't mind me asking ?

 

[Birdman]

The 1-2 shift problem involved replacement clutches and these were rebuilt by Lancaster MB - or rather, a specialist they brought in for the purpose from elsewhere, and were done under warranty. It would have been a few grand otherwise.

If you're getting flaring during the upchange then this probably involves the clutches imo. If flaring occurs only on the downchange (going from 3-2 or 2-1) then the air mass sensor or an electrical fault in the gearbox may be the answer, with luck. In either case you should check the history to ensure the ATF has been changed at least once. While supposedly sealed for life the autobox needs new fluid/filter periodically. Some madmen do it every few thousand miles. More reasonable souls settle for 50-60,000 between changes. Either way, you need to check. But getting the star fault codes is the next move imo.

 

[Dieselman]

Low ATF will give flaring between changes. Have you checked the level?

 

[Cool Mart]

New ATF and filter = problem solved !

 

[Birdman]

That's interesting. At what mileage was it changed?

 

[Cool Mart]

I can't find any evidence in the history of it ever being changed up until now - 102,000 miles.

The garage described the oil as 'burnt'

Changes are slicker now, they all take the same amount of time and with no flaring.

 

[Birdman]

I can't find any evidence in the history of it ever being changed up until now - 102,000 miles.

The garage described the oil as 'burnt'

Changes are slicker now, they all take the same amount of time and with no flaring.

Thanks. That disposes if the 'sealed for life' claim pretty decisively. They meant, 'sealed for 100,000 miles and then exchanged'. Since MB put millions of test miles into each new model before launch, one wonders what they were actually thinking when they made the claim.

Maybe they weren't!

 

[Dieselman]

Thanks. That disposes if the 'sealed for life' claim pretty decisively. They meant, 'sealed for 100,000 miles and then exchanged'. Since MB put millions of test miles into each new model before launch, one wonders what they were actually thinking when they made the claim.

Maybe they weren't!

Isn't 100k the rated life of the box?
After 80k if a 722.6 has a problem techs are advised to change the whole box.

 

[Birdman]

Isn't 100k the rated life of the box?
After 80k if a 722.6 has a problem techs are advised to change the whole box.

If it is rated at 100,000 (news to me) it doesn't add up. I would guess it is one of those cover stories manufacturers cook up so they can say, "We don't expect our stuff to last THAT long" and everyone is happy. Plus, you can buy an extended warranty from MB for 6years/120,000 miles at £730 per year for my AMG (which has the W140 CL600 box)and MB can't have costed in a new gearbox at 100K at their prices. Can they?