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Discussion Starter #1
Hello,
Running low on ideas for a gearbox fix. Jerks through gears until it’s warmed up in S and W mode.
Here’s what’s been changed so far...

Oil
Filter
Torque convertor been bled
Gearbox control unit

The gearbox control unit was done today and my partner said it’s still jerky but a lot better. Sometimes you don’t have time to warm it up. But if you don’t it’ll rev high and have no power!!

Any ideas?? Everything that’s been done to the car before we bought it hasn’t been done properly, but obviously this is the main problem right now.

Thanks
Jayne
 

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Registered 2002 SLK230
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12 Posts
Hi Jayne,

I too recently bought a 230 and although I didn't have the same troubles as you, I did find that the "professional" that maintained the car for the previous owner didn't get the gearbox oil level right and that can cause bad changing symptoms. To get it right you need to get the transmission hot to 80C and use the special dipstick (which is not provided with the car) to check it. That's definitely the first check to do if it hasn't been done already.

Ray
 

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Discussion Starter #3
Thanks for the reply Ray.
I think the oil level was checked (we had to buy one of those huge flexible dip sticks when we changed it) but I’ll ask my partner to double check it again when we get into work in the morning. Honestly I’m hoping it’s either high or low and that’s the problem and we can fix it.
 

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Discussion Starter #5
Thanks for the links. After reading through them I t looks like the right oil level is crucial. That’s the job for tomorrow now. Fingers crossed!!
 

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Registered 2001 SLK320
Joined
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910 Posts
Hello,
Running low on ideas for a gearbox fix. Jerks through gears until it’s warmed up in S and W mode.
Here’s what’s been changed so far...

Oil
Filter
Torque convertor been bled
Gearbox control unit

The gearbox control unit was done today and my partner said it’s still jerky but a lot better. Sometimes you don’t have time to warm it up. But if you don’t it’ll rev high and have no power!!

Any ideas?? Everything that’s been done to the car before we bought it hasn’t been done properly, but obviously this is the main problem right now.

Thanks
Jayne

Dave 2302 probably better than I on this but what exactly do you mean the TC has been bled? It should be drained when doing a trans service but it has to be refilled to the correct level.
Also which control unit are we talking about? The TCU that connects the trans to the ECU or the conductor plate? There are also a number of solenoids in the valve body that could be at fault as well as some speed sensors.
 

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Premium Member 2002 SLK320
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764 Posts
Dave 2302 probably better than I on this but what exactly do you mean the TC has been bled? It should be drained when doing a trans service but it has to be refilled to the correct level.
Also which control unit are we talking about? The TCU that connects the trans to the ECU or the conductor plate? There are also a number of solenoids in the valve body that could be at fault as well as some speed sensors.
You cannot drain the TC on all R170s. Some (I think it's the later ones) you can only drain the transmission and not the torque converter (there is no drain plug for it). So a fluid change requires less fluid*. There may well be a way of syphoning the fluid out, but it's not usual.
* Unless, of course you drain the transmission, refill, use car and repeat the process. Then it would require more fluid:grin:.
 

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Premium Member 2002 R170 SLK V8 5.0
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3,539 Posts
Hi,

722.6, (well any Auto I've ever come across in many years as a Rebuilder), does not require T/C Bled, even with a brand new Converter and Tranny that has no oil in it, fit into Car, add 4 liters, start Engine, top Fluid to Max, short road test, re check Fluid and add top up if necessary .................

Simples :wink:

The Pump fills the Converter, Valve Block and Cooler as soon as you start the Engine, that is why Auto Levels must always be checked with Engine Idling in P at normal Temperature, (80c)

HTH, Cheers Dave
 

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Registered 1998 SLK230
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42 Posts
Mine was doing the same thing. I dropped the transmission pan, changed the filter inside the pan, new gasket, reinstalled, Ravenol fluid, and my problem was gone. It looked like the original trans filter. I'm finding more and more regular service items that were never done.... Running better every time I change something that was previously never attended to...
 

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Premium Member 2001 SLK200K/2001 SLK320
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2,279 Posts
Mine was doing the same thing. I dropped the transmission pan, changed the filter inside the pan, new gasket, reinstalled, Ravenol fluid, and my problem was gone. It looked like the original trans filter. I'm finding more and more regular service items that were never done.... Running better every time I change something that was previously never attended to...

To be fair, as the 722.6 was supposed to be "sealed for life" I don't think it ever would have been part of a service regimen.

According to one of Kent Bergsma's videos on MB Medic, the MB techs have since managed to work out that any damage/sludging/blockaging/shaving etc. to the 'box will occur within the first 43k miles (70k kms) from new and should ideally be serviced before that magical figure is reached. The 'box is then "sealed for life" for a 2nd time, no one has yet to answer the question of "how long is life?" though
 

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Premium Member 2002 R170 SLK V8 5.0
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3,539 Posts
To be fair, as the 722.6 was supposed to be "sealed for life" I don't think it ever would have been part of a service regimen.

According to one of Kent Bergsma's videos on MB Medic, the MB techs have since managed to work out that any damage/sludging/blockaging/shaving etc. to the 'box will occur within the first 43k miles (70k kms) from new and should ideally be serviced before that magical figure is reached. The 'box is then "sealed for life" for a 2nd time, no one has yet to answer the question of "how long is life?" though
Hi,

I can answer that ..............

When the Mfrs Warranty runs out ..............

After that they don't give one cahoot >:D
 
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Discussion Starter #12
Thanks for all the replies.
After loads of messing around with the fluid levels it seems a lot better. I haven’t been able to use it daily because of the weather (seals, another problem!!) But just moving it outside the workshop everyday and a little drive around the industrial estate with little time to warm up is loads better. Still a bit jerky in S but so much smoother.

We’ve got the level right in between the markers. Is that right?

Yeah the filled for life is a load of rubbish!! I also have a 2004 Mini Cooper cvt with so many gearbox problems it’s amazing!! Apparently that’s filled for life too, I got it on 52k miles so I’m not exactly sure how long “life” is.
 

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Premium Member 2001 SLK200K/2001 SLK320
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2,279 Posts
Thanks for all the replies.
After loads of messing around with the fluid levels it seems a lot better. I haven’t been able to use it daily because of the weather (seals, another problem!!) But just moving it outside the workshop everyday and a little drive around the industrial estate with little time to warm up is loads better. Still a bit jerky in S but so much smoother.

We’ve got the level right in between the markers. Is that right?

Yeah the filled for life is a load of rubbish!! I also have a 2004 Mini Cooper cvt with so many gearbox problems it’s amazing!! Apparently that’s filled for life too, I got it on 52k miles so I’m not exactly sure how long “life” is.


The general rule of thumb appears to be that if you buy a Merc with a 722.6 and there is no history of the trans fluid and filter being changed, then ideally it's something that should be done

Level ground, engine running at operating temp, fluid inbetween the two top markers :tu:


MB Trans Fluid Check



My bad when I earlier said that Kent was at medic, I meant source obviously :)
Full series of 3 vids:






HTH
 

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Registered 1998 SLK230
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42 Posts
To be fair, My car looked very neglected when I bought it. I figured on doing every service change possible. It is pushing 178,000 after all.... I also placed a rare earth magnet in the trans pan, as there was none. I don't believe the filter was EVER changed. It was so clogged, the engine HAD to warm up to thin the fluid enough to pass through...
 
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