Gearbox trouble, big or small..?
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
Gearbox trouble, big or small..?
Hi.
First of all, I'm a bit surprised to see that here is no thread alternative for S600..?
(My car is a CL600, but I wanted to increase my chances of response by writing here also, since the same gearbox sits in the S600. Probably even in 55AMG & 65AMG, only with quicker TCU.)
Anyway,
Last week I bought a CL600 from 2008 in Germany and drove it home (to Sweden).
On my way home I spent a night at a hotel, about half way home.
The next morning the car was of course cold, and made TERRIBLE gear changes to second & third gear!!!
The guy had me fooled of course, by showing me the car all warmed up!
My mechanic says that the car does rev quite high before it moves, even when warmed up (like a manual car with clutch all worned out).
So I now have three choices;
- Flush the gearbox for about 500 dollars (small problem).
or
- Buy a used gearbox at eBay, för about 1.000 dollars.
or
- Renovate my gearbox for about 2.000 dollars (big problem).
What would you guys choose..?
And do you have any experience on this matter perhaps?
Oh, and btw the purchase was made from a private person, so no use in even call him about this. It's an obvious con.
Thankful for your thoughts!
Best regards
Roger
First of all, I'm a bit surprised to see that here is no thread alternative for S600..?
(My car is a CL600, but I wanted to increase my chances of response by writing here also, since the same gearbox sits in the S600. Probably even in 55AMG & 65AMG, only with quicker TCU.)
Anyway,
Last week I bought a CL600 from 2008 in Germany and drove it home (to Sweden).
On my way home I spent a night at a hotel, about half way home.
The next morning the car was of course cold, and made TERRIBLE gear changes to second & third gear!!!
The guy had me fooled of course, by showing me the car all warmed up!
My mechanic says that the car does rev quite high before it moves, even when warmed up (like a manual car with clutch all worned out).
So I now have three choices;
- Flush the gearbox for about 500 dollars (small problem).
or
- Buy a used gearbox at eBay, för about 1.000 dollars.
or
- Renovate my gearbox for about 2.000 dollars (big problem).
What would you guys choose..?
And do you have any experience on this matter perhaps?
Oh, and btw the purchase was made from a private person, so no use in even call him about this. It's an obvious con.
Thankful for your thoughts!
Best regards
Roger
Last edited by maxabo; Nov 20, 2025 at 05:07 AM.
Member
Joined: Nov 2016
Posts: 160
Likes: 46
S-65 AMG
If you can have someone rebuild an S600 trasmission for $2000 including Removal and Installation I would do that.
There are a ton of Dodge/Mercedes transmissions available on Ebay, but I am not sure they are compatible with the specific version in the V12 cars, and finding a good V12 Trasmission is going to be difficult.
I have a tool that cross references used auto parts in the American market. You put in what you need (2008 W221 S600 transmission) and it gives you all the parts that will fit. What it came back with was only S600 and CL600 transmissions.
There are a ton of Dodge/Mercedes transmissions available on Ebay, but I am not sure they are compatible with the specific version in the V12 cars, and finding a good V12 Trasmission is going to be difficult.
I have a tool that cross references used auto parts in the American market. You put in what you need (2008 W221 S600 transmission) and it gives you all the parts that will fit. What it came back with was only S600 and CL600 transmissions.
Last edited by auburn2; Nov 24, 2025 at 07:47 PM.
MBWorld Fanatic!
Joined: Apr 2009
Posts: 1,264
Likes: 367
'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
Hi.
First of all, I'm a bit surprised to see that here is no thread alternative for S600..?
(My car is a CL600, but I wanted to increase my chances of response by writing here also, since the same gearbox sits in the S600. Probably even in 55AMG & 65AMG, only with quicker TCU.)
Anyway,
Last week I bought a CL600 from 2008 in Germany and drove it home (to Sweden).
On my way home I spent a night at a hotel, about half way home.
The next morning the car was of course cold, and made TERRIBLE gear changes to second & third gear!!!
The guy had me fooled of course, by showing me the car all warmed up!
My mechanic says that the car does rev quite high before it moves, even when warmed up (like a manual car with clutch all worned out).
So I now have three choices;
- Flush the gearbox for about 500 dollars (small problem).
or
- Buy a used gearbox at eBay, för about 1.000 dollars.
or
- Renovate my gearbox for about 2.000 dollars (big problem).
What would you guys choose..?
And do you have any experience on this matter perhaps?
Oh, and btw the purchase was made from a private person, so no use in even call him about this. It's an obvious con.
Thankful for your thoughts!
Best regards
Roger
First of all, I'm a bit surprised to see that here is no thread alternative for S600..?
(My car is a CL600, but I wanted to increase my chances of response by writing here also, since the same gearbox sits in the S600. Probably even in 55AMG & 65AMG, only with quicker TCU.)
Anyway,
Last week I bought a CL600 from 2008 in Germany and drove it home (to Sweden).
On my way home I spent a night at a hotel, about half way home.
The next morning the car was of course cold, and made TERRIBLE gear changes to second & third gear!!!
The guy had me fooled of course, by showing me the car all warmed up!
My mechanic says that the car does rev quite high before it moves, even when warmed up (like a manual car with clutch all worned out).
So I now have three choices;
- Flush the gearbox for about 500 dollars (small problem).
or
- Buy a used gearbox at eBay, för about 1.000 dollars.
or
- Renovate my gearbox for about 2.000 dollars (big problem).
What would you guys choose..?
And do you have any experience on this matter perhaps?
Oh, and btw the purchase was made from a private person, so no use in even call him about this. It's an obvious con.
Thankful for your thoughts!
Best regards
Roger
First thing I would do is check the fluid level, which is sort of your first option. I’d change the filter while at it, and inspect the trans plug O-ring for leaks. Leaky fluid can wick up the harness and into the TCU, destroying it.
Doing this will tell you whether the other two options are of any value to you at all.
Conductor plates are also known issues on these transmissions, often from leaky fluid through the harness but not always. Best case, it’s a simple fluid and filter. Worst case, well that’s a lot worse, so start there and report back.
Cheers and GL,
maw
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Joined: Sep 2007
Posts: 1,481
Likes: 310
95 SL600
Cold hard shifts are usually bad or contaminated solenoids. $500 for a flush seems high when a used transmission is $1000. Valvoline max life transmission fluid is relatively inexpensive and what I would use. These transmissions are pretty robust, but not being able to repair a 20 plus year old car puts you and your bank account at an extreme disadvantage especially with any v12 Mercedes. The radiators have also been known to leak coolant into the transmission as well.
Senior Member
Joined: Oct 2011
Posts: 320
Likes: 185
From: Philadelphia
2002 CLK55 AMG: 2004 S55 AMG: 2009 C63
Sounds like a low fluid issue to me. Start by checking the fluid (Red Safety Lock Cap behind engine near fire wall) just break it off, replacements are pennies on the dollar. (or take a tiny flat head and you can get it off) Get a long dip stick from amazon and stick it down there and see where it comes up. If it needs fluid, add some and take it for a drive after its cold.
Start there first. If that fixes the issue, do a complete trans service. Filter, conductor plate, 13 pin connector, etc. FCP Sells the kit. As mentioned above these transmission are pretty robust, it wouldn't suprise me to be low on fluid due to a leak somewhere.
GL
- Joe
Start there first. If that fixes the issue, do a complete trans service. Filter, conductor plate, 13 pin connector, etc. FCP Sells the kit. As mentioned above these transmission are pretty robust, it wouldn't suprise me to be low on fluid due to a leak somewhere.
GL
- Joe
MBWorld Fanatic!
Joined: Apr 2009
Posts: 1,264
Likes: 367
'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
Sounds like a low fluid issue to me. Start by checking the fluid (Red Safety Lock Cap behind engine near fire wall) just break it off, replacements are pennies on the dollar. (or take a tiny flat head and you can get it off) Get a long dip stick from amazon and stick it down there and see where it comes up. If it needs fluid, add some and take it for a drive after its cold.
Start there first. If that fixes the issue, do a complete trans service. Filter, conductor plate, 13 pin connector, etc. FCP Sells the kit. As mentioned above these transmission are pretty robust, it wouldn't suprise me to be low on fluid due to a leak somewhere.
GL
- Joe
Start there first. If that fixes the issue, do a complete trans service. Filter, conductor plate, 13 pin connector, etc. FCP Sells the kit. As mentioned above these transmission are pretty robust, it wouldn't suprise me to be low on fluid due to a leak somewhere.
GL
- Joe
OP, you were on the right track when you asked the question. Stay with that at least through Option One. If it gets more complicated than that there are plenty of us here to advise you beyond "diagnose".
maw
Last edited by maw1124; Nov 26, 2025 at 08:49 PM.
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
We have now done a diagnostic test, and that showed no (zero) failures, strangly enough!
I'm very glad for your responses guys!
I have also now learned that according to Mercedes, they recommend an oil change by 60.000 kilometers (37.000 miles), and never again after that.
And since the history of this car is pretty unknown, I would not be surprised if the original oil still is in there.
I will check with the mechanic if he manages to "check the fluid (Red Safety Lock Cap behind engine near fire wall) just break it off, replacements are pennies on the dollar."
Otherwise I will keep my appointment on the Dec 11 for a flush. I have already bought the oil therefor (20 liters Dexron 6 for about 130 dollars feels like a bargain in this context).
I'm very glad for your responses guys!
I have also now learned that according to Mercedes, they recommend an oil change by 60.000 kilometers (37.000 miles), and never again after that.
And since the history of this car is pretty unknown, I would not be surprised if the original oil still is in there.
I will check with the mechanic if he manages to "check the fluid (Red Safety Lock Cap behind engine near fire wall) just break it off, replacements are pennies on the dollar."
Otherwise I will keep my appointment on the Dec 11 for a flush. I have already bought the oil therefor (20 liters Dexron 6 for about 130 dollars feels like a bargain in this context).
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Member
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From: Ohio
2005 S55 AMG, 2001 SL500
Sounds like your issues are similar to what I was experiencing in my '05 S55 which also showed no codes. The PO had been chasing it and had tried two new conductor plates without success. Long story short the issue was vastly improved by flushing the tranny/torque convertor and installing a rebuilt valve body and TCU sourced through MK-Ultra Electronics. I opted for Fuchs Titan 4134 transmission fluid for the final fill which is also compatible with your car. I can't say it shifts as new as I have no experience with a new 722.6 but the difference is night and day. Smooth yet crisp up and down the gears hot or cold.148,000 miles on the car when repaired,153,000 miles now. All-in-all I'm very pleased with the results. Good luck!
722.6 AMG OEM Stock Speed Shift 240-0106 Valve Body With Bluetop Solenoids – Mk-Ultra Electronics
Auto Trans Fluid ATF 4134 (5 Liters) - FUCHS 800350077 | FCP Euro
722.6 AMG OEM Stock Speed Shift 240-0106 Valve Body With Bluetop Solenoids – Mk-Ultra Electronics
Auto Trans Fluid ATF 4134 (5 Liters) - FUCHS 800350077 | FCP Euro
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Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
I have already bought the oil (Dexron 6).
Veeery exiting to see how the car acts after that...some say there is a risk that I can't even drive it off the lot afterwards!
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Joined: Apr 2009
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'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
Even if that happens you just learned a new valve body is only $500.
This M113 engine and 722.6 transmission is one of Mercedes' best ever combinations.
Think about how many '96-'06 cars wore a 430, 500 or 55 on the trunk and let that sink in.
One of Mercedes' best ever.
That didn't happen because people couldn't change their transmission fluid.
Let us know how it goes, and GL.
maw
Member
Joined: Sep 2022
Posts: 155
Likes: 118
From: Ohio
2005 S55 AMG, 2001 SL500
Nothing against Dexron VI but I'm particular to the point of being obsessive.
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
MBWorld Fanatic!
Joined: Apr 2009
Posts: 1,264
Likes: 367
'06 MB S55 AMG; '04 Audi Allroad 4.2; '05 BMW M3 Conv.; '92 MB 500E
maw
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
Btw, my issue was not about maintenance (could be because of lack there of, but) it has clearly gone way passed that stage...if you read the beginning.
Last edited by maxabo; Dec 8, 2025 at 10:13 AM.
Member
Joined: Sep 2022
Posts: 155
Likes: 118
From: Ohio
2005 S55 AMG, 2001 SL500
Here's a link to MK-Ultra: Stock Replacement Mercedes Transmission Control Modules EGS52 – Mk-Ultra Electronics You should probably reach out to them. Good Luck!
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
Sorry to hear that. I'm assuming the TCU was checked for fluid intrusion too? If it's wet, it's probably as good as cooked. Happened to me and even after being cleaned it wouldn't communicate with Star or Xentry diagnostics. Installed a refurbished stock TCU sourced through MK-Ultra. It could communicate but no real improvement, so I did some research which narrowed things down to conductor plate, valve body sleeves, and solenoids. The conductor plate had been replaced twice by the PO without improvement, so I eliminated that. Then, as luck would have it, I found the refurbished valve body on the MK-Ultra website which included new valve sleeves and blue top solenoids. Ordered that and had it installed. Bingo! Good as new? I don't think so but it's night and day. Costs: $130.00 for TCU - $500.00 for valve body after core return - $905.00 for installation which included all fluid, gaskets, PIN connector, and required TCU adaptation.
Here's a link to MK-Ultra: Stock Replacement Mercedes Transmission Control Modules EGS52 – Mk-Ultra Electronics You should probably reach out to them. Good Luck!
Here's a link to MK-Ultra: Stock Replacement Mercedes Transmission Control Modules EGS52 – Mk-Ultra Electronics You should probably reach out to them. Good Luck!
In my case we haven't checked the TCU, because the electrical contact (socket on the transmission) was fine. I've heard of oil travelling from there to the TCU.
I've seen the blue top solenoids on YouTube. Do they make the gear changes faster, or what..?
Last edited by maxabo; Dec 18, 2025 at 01:49 AM.
Member
Joined: Sep 2022
Posts: 155
Likes: 118
From: Ohio
2005 S55 AMG, 2001 SL500
Waow! Glad to hear that! And your symptoms were simular to my symptoms..?
In my case we haven't checked the TCU, because the electrical contact (socket on the transmission) was fine. I've heard of oil travelling from there to the TCU.
I've seen the blue top solenoids on YouTube. Do they make the gear changes faster, or what..?
In my case we haven't checked the TCU, because the electrical contact (socket on the transmission) was fine. I've heard of oil travelling from there to the TCU.
I've seen the blue top solenoids on YouTube. Do they make the gear changes faster, or what..?
Here's a link to a FCP Euro tutorial describing a 722.6 performance upgrade. Rather long as the entire process is shown, but well worth watching even if you have a mechanic do the work. Bing Videos After watching it myself I came to the conclusion my issues were most likely being caused by worn valve body overlap sleeves, but I didn't have the interest / equipment / tools to replace them. So, from both a labor and parts cost perspective finding a plug and play valve body refurbished by a trusted source was a real plus. Install. Adapt the TCU. Done.
Good luck!
Last edited by CICBarkeep; Dec 18, 2025 at 08:34 AM.
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
Yes, my symptoms were very similar to yours although I did NOT experience the high revs before the car would move issue you mentioned. And yes, the blue tops offer higher line pressure = quicker shifts.
Here's a link to a FCP Euro tutorial describing a 722.6 performance upgrade. Rather long as the entire process is shown, but well worth watching even if you have a mechanic do the work. Bing Videos After watching it myself I came to the conclusion my issues were most likely being caused by worn valve body overlap sleeves, but I didn't have the interest / equipment / tools to replace them. So, from both a labor and parts cost perspective finding a plug and play valve body refurbished by a trusted source was a real plus. Install. Adapt the TCU. Done.
Good luck!
Here's a link to a FCP Euro tutorial describing a 722.6 performance upgrade. Rather long as the entire process is shown, but well worth watching even if you have a mechanic do the work. Bing Videos After watching it myself I came to the conclusion my issues were most likely being caused by worn valve body overlap sleeves, but I didn't have the interest / equipment / tools to replace them. So, from both a labor and parts cost perspective finding a plug and play valve body refurbished by a trusted source was a real plus. Install. Adapt the TCU. Done.
Good luck!
I think the high reving from standstill have gotten better now, some days after the flush...at least we think so!
So your car when cold, was also really slamming hard in to second gear...to then shift normal higher up in gears..?
And when warm it shifted normal all threw 1-5..?
How much do these "blue-top-solenoids" cost, and where do I best buy them..?
Last edited by maxabo; Dec 20, 2025 at 05:15 AM.
Member
Joined: Sep 2022
Posts: 155
Likes: 118
From: Ohio
2005 S55 AMG, 2001 SL500
Thank you soo much! At 16:10 it takes off. :-)
I think the high reving from standstill have gotten better now, some days after the flush...at least we think so!
So your car when cold, was also really slamming hard in to second gear...to then shift normal higher up in gears..?
And when warm it shifted normal all threw 1-5..?
How much do these "blue-top-solenoids" cost, and where do I best buy them..?
I think the high reving from standstill have gotten better now, some days after the flush...at least we think so!
So your car when cold, was also really slamming hard in to second gear...to then shift normal higher up in gears..?
And when warm it shifted normal all threw 1-5..?
How much do these "blue-top-solenoids" cost, and where do I best buy them..?
The link I sent earlier should have been your first clue but.......Genuine and OEM Replacement Car Parts Online | BMW Volvo Audi VW Mercedes Porsche Saab | FCP Euro Good luck man. You've earned "you're on your own from here" status.
Member
Joined: Nov 2016
Posts: 160
Likes: 46
S-65 AMG
You did not say what the specific problem is with the shift. If it is flaring the 2-3 shift you might try this:
TransGo - Mercedes 722.6 SHIFT KIT® Valve Body Repair Kit
The transgo really know what they are doing.
TransGo - Mercedes 722.6 SHIFT KIT® Valve Body Repair Kit
The transgo really know what they are doing.
