Autobox query

[Vlad]

Just been to see a 320 CLK....lovely car, but suspect that its got a dodgy gearbox as the gearbox will not hold the car on a slope, even on the slightest of inclines it will roll back as soon as you lift your foot off the brake, whereas the car should just hold its position even if you didn't have your foot on the brake.

With this in mind, I suspect that the Torque Convertor is knackered......if this is the case, why would a torque convertor fail and will it eventually lead to the rest of the gearbox failing.....the autobox itself had nice smooth changes, kicked down as it should and gave off no nasty noises.

Any idea how much to buy a new torque convertor (I suspect @ £900 just for the convertor) and to fit it?

 

[panason1c]

Nothing wrong, dont worry......this is 'normal' with the 722.6 auto gearbox........many other makes auto's will 'lock' on a hill but mercedes (722.6) transmissions do not have this feature built into the 'box and will readily roll back on the slightest of slopes.

 

[Ian B Walker]

Any idea how much to buy a new torque convertor (I suspect @ £900 just for the convertor) and to fit it?

£927 plus vat. I have just bought one for a CLK240 which has a split rad to ATF interface. Easy box to drop out though. Box out and in should take no longer than 6 hours.

 

[renmure]

Nothing wrong, dont worry......this is 'normal' with the 722.6 auto gearbox........many other makes auto's will 'lock' on a hill but mercedes (722.6) transmissions do not have this feature built into the 'box and will readily roll back on the slightest of slopes.

Phew... I was begining to worry that mine had a problem as well!!

 

[Vlad]

I'm not sure that it is normal....my other half has a 320 Cabrio and I have also previously had a 320 Coupe and both hold on the steepest of hills, feet off the brakes with no roll back....this one I tested today rolled back on the slightest of inclines.

Any further thoughts????

 

[Vlad]

£927 plus vat. I have just bought one for a CLK240 which has a split rad to ATF interface. Easy box to drop out though. Box out and in should take no longer than 6 hours.

Ian...thanks for that...by the way does the contamination of the autobox with coolant also wreck the autobox in addition to the torque convertor and in the case of the 240 that you have just done, were there any un-toward noises from the torque convertor...ie grinding etc?......just trying to gleen some more info in order that I can add it too the memory banks just in case it comes in useful in the future

 

[Ian B Walker]

Ian...thanks for that...by the way does the contamination of the autobox with coolant also wreck the autobox in addition to the torque convertor and in the case of the 240 that you have just done, were there any un-toward noises from the torque convertor...ie grinding etc?......just trying to gleen some more info in order that I can add it too the memory banks just in case it comes in useful in the future

Vlad, the symptoms of my problem were, hesitation in acceleration, horrid thumping from the rear end (first thought it was the diff) and a slight rumble from the bell housing. I took it to my dealers for a diagnostic as I was not able to put my finger on it. They said that the converter and rad were shot after doing a glycol test. The trans oil was bright orange . The box moves though the gears very smoothly and I am led to believe that it is ok. I threw 20 ltrs of atf though it to flush it out (Dexron II, as suggested by the dealers). I hope this is of help to you. And yes it should stop on a hill whilst in gear.

 

[Vlad]

Cheers for that Ian...always nice to learn something new.

 

[panason1c]

VLAD, Have a look at this thread, i think you will find that the general concensus is that some do and some dont.....it's normal!

http://forums.mercedesclub.org.uk/showthread.php?t=18145&highlight=rolls+back+hill


ps....my 2002 ML is fitted with the same gearbox (722.6) it also rolls back on an incline, it did the same with it's original 'box and it still does even with a brand new gearbox and torque converter fitted just over a year ago. When i mentioned this to my MB dealer (Taunton) they said it was 'normal' for MB's to roll back that dont have the 'hill start' feature. (or something like that)

 

[television]

The fact that a car rolls back on a hill means nothing and there is no test for this, the gearbox does not have a fault whin/if it rolls back, a touch of an increase in idle speed would stop the car from rolling back.

The Glycol fault one should not be in this thread, the Glycol issue that affects the 203,209 and 211 has nothing to do with this

 

[panason1c]

http://www.mbclub.co.uk/forums/showthread.php?t=28447

 

[Vlad]

Update....this CLK that I've been looking at.

As mentioned the car had absolutely no hold function on a hill whatsoever...ie lift off the brakes and it rolled back like a train out of control...not good.

Discussed it with vendor and they took it into their Merc specialist, who cleaned the throttle body, which helped clean up the idle which was low.

Car now holds on a steep hill ...inline with what I would expect of a Merc, ie with only minimal roll back...ie you have plenty of time to move your foot from brake to accelerator without crashing into the car behind you.

This may be of interest to you if your Merc (V6 engine) is suffering from uncontrolled roll back as opposed to very gradual roll back on a hill.

 

[panason1c]

Thanks for the update, which demonstrates that the actual gearbox isnt faulty if the car rolls back on an incline and that it is simply the 'creep' effect that prevents the car from rolling back depending on the idle speed of the engine.

I experimented with my ML yesterday, it will normally roll back even on a slight incline but increasing the revs by only 100rpm prevented it rolling back on a fairly steep incline.

 

[television]

Thanks for the update, which demonstrates that the actual gearbox isnt faulty if the car rolls back on an incline and that it is simply the 'creep' effect that prevents the car from rolling back depending on the idle speed of the engine.

I experimented with my ML yesterday, it will normally roll back even on a slight incline but increasing the revs by only 100rpm prevented it rolling back on a fairly steep incline.

A 25 rpm increase in idle stops mine rolling back

 

[stevesey]

Mine holds really well, but it creeps more that I'd like - would be prepared to swap a bit of one for the other (but not that worried that I'll pay a dealer to hook it up and drop the idle speed).

 

[panason1c]

A 25 rpm increase in idle stops mine rolling back

It's all relative to what the revs normally are at idle on different models.

That's why, as i said earlier, some will roll back, some won't.

 

[television]

Mine holds really well, but it creeps more that I'd like - would be prepared to swap a bit of one for the other (but not that worried that I'll pay a dealer to hook it up and drop the idle speed).

That will make all of the difference

 

[jaymanek]

did you have it in Winter or Summer as this makes a huge difference on how well it holds on a hill... are you sure the switch wasnt in winter the second time..

 

[jamesmc]

My CLK would hold on a hill but when the MAF started to play up sometimes, after a run, the tickover would be low plus the engine would miss a bit, that was enough to allow it to roll on a slight hill. Now sorted and ticking over at normal speed all is well again on hill holds.

I have noticed that on steep hill it will creep a little which I accept as normal.

 

[Vlad]

It was in "S" mode