Flush or replace gearbox..?
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
Flush or replace gearbox..?
Hi. 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 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.
or
- Buy a used gearbox at eBay, för about 1.000 dollars.
or
- Renovate my gearbox for about 2.000 dollars.
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
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 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.
or
- Buy a used gearbox at eBay, för about 1.000 dollars.
or
- Renovate my gearbox for about 2.000 dollars.
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 04:36 AM.
MBWorld Fanatic!
Joined: Oct 2021
Posts: 1,194
Likes: 636
From: Iowa
2008 CL550, 2022 EQB 300, 2023 EQS 450 4Matic
Hi. 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 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.
or
- Buy a used gearbox at eBay, för about 1.000 dollars.
or
- Renovate my gearbox for about 2.000 dollars.
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
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 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.
or
- Buy a used gearbox at eBay, för about 1.000 dollars.
or
- Renovate my gearbox for about 2.000 dollars.
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
MBWorld Fanatic!
Joined: Feb 2017
Posts: 2,307
Likes: 1,210
From: Baltimore County, MD
'13 s212 63 p30. '06 LX470
Diy a drain and fill. Once you verify the issue is there with new fluid at the proper level, you can make the best choice. There is no way to know if a used part will fail after install, so imo, a rebuild would be the way. Make sure you consult with someone that has STAR DAS in order to properly diagnose the faulty part or function.
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
I feel bad for you...I got hosed on a private sale on my CL also. The seller was a liar--so disappointing. Before you start spending money, have you run a Quick Test on it with a code reader--preferably a real Xentry setup? It might point you in a more precise direction. Could be something minor. With that said, if you plan to keep your car a long time like me, I replace everything I can at points like this, because after 18 years of use the parts are worn out and need refreshing. Seals have gotten hard, plastic brittle, electronic connections deteriorated. Are you going to do some of the work yourself?
Hopefully that shows us something!
Yes I'm planning on keeping this a number of years, for it to be driven some few miles summer time.
On tuesday it's going to the mechanic...and I think we have set our mindes to a couple of oil changes, without flushing.
MBWorld Fanatic!
Joined: Oct 2021
Posts: 1,194
Likes: 636
From: Iowa
2008 CL550, 2022 EQB 300, 2023 EQS 450 4Matic
Keep us posted on your progress. FWIW, you should probably replace all of the fluids, unless you are sure they've been done previously. Also, clean out all of the drains around the windshield and sunroof, in case the former owner never did--prevents water incursion and the assorted troubles that come with it.
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
Keep us posted on your progress. FWIW, you should probably replace all of the fluids, unless you are sure they've been done previously. Also, clean out all of the drains around the windshield and sunroof, in case the former owner never did--prevents water incursion and the assorted troubles that come with it.
I will.
Senior Member
Joined: Aug 2021
Posts: 335
Likes: 33
2008 E320 Bluetec, 1987 190e 2.6, 2007 CL600
I bought a 2007 CL600 with similar issues of gearbox slipping. I scan and it has speed sensor y3/6n3 codes so i am starting out with replacing the conductor plate and upgraded solenoids with full trans service and resetting codes and adaptations. This is probably the cheapest and most impactful route starting out. Are you able to scan the car, mine has no CEL but it’s going into limp mode
This is not a surprising or unexpected issue at this age but what mileage are you at? We have the 722.6 transmission and this is a common issue when the fluid hasn’t been changed even more so on the hot and heavy v12 I’d suspect
This is not a surprising or unexpected issue at this age but what mileage are you at? We have the 722.6 transmission and this is a common issue when the fluid hasn’t been changed even more so on the hot and heavy v12 I’d suspect
Last edited by BetterDaze; Nov 29, 2025 at 01:04 AM.
Trending Topics
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
I bought a 2007 CL600 with similar issues of gearbox slipping. I scan and it has speed sensor y3/6n3 codes so i am starting out with replacing the conductor plate and upgraded solenoids with full trans service and resetting codes and adaptations. This is probably the cheapest and most impactful route starting out. Are you able to scan the car, mine has no CEL but it’s going into limp mode
This is not a surprising or unexpected issue at this age but what mileage are you at? We have the 722.6 transmission and this is a common issue when the fluid hasn’t been changed even more so on the hot and heavy v12 I’d suspect
This is not a surprising or unexpected issue at this age but what mileage are you at? We have the 722.6 transmission and this is a common issue when the fluid hasn’t been changed even more so on the hot and heavy v12 I’d suspect
If you with CEL mean diagnostic errors, my car showed no errors (zero) when we did a diagnostic test on the transmission.
On tuesday Dec. 11 I'm flushing the gearbox.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Senior Member
Joined: Aug 2021
Posts: 335
Likes: 33
2008 E320 Bluetec, 1987 190e 2.6, 2007 CL600
Sorry to hear but hopefully you can source a v12 722.6 to use? Or will your mechanic help rebuild it?
i think the previous owners of these cars got too happy with the paddle shifts not knowing what they are doing and burning the clutches up
i did do the service on mine and all codes went away except “slipping in gear 4” but I ran out of new trans fluid to put in, I’m hoping a proper fill will fix that but if not I’ll be in the same boat
i think the previous owners of these cars got too happy with the paddle shifts not knowing what they are doing and burning the clutches up
i did do the service on mine and all codes went away except “slipping in gear 4” but I ran out of new trans fluid to put in, I’m hoping a proper fill will fix that but if not I’ll be in the same boat
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 444
Likes: 8
From: Sweden
2008 MB CL600. 2020 MB E300 de. 1987 BMW M535i.
Senior Member
Joined: Aug 2021
Posts: 335
Likes: 33
2008 E320 Bluetec, 1987 190e 2.6, 2007 CL600
I got mine all put back together and its driving normal until it attempts to shift into 4th. Car is scary fast btw I’m in love with it!!! I reset the adaptations but it’s still doing the same thing, I think I’m missing something within the menus. I reset the shifts but maybe there a certain values/ratios that need to be entered or you need to code the shifts some other way?
i left it alone for now since i only bought this car as a future project/toy but i am contemplating parking the car for a year and saving up to get an upgraded transmission or rebuild kit, it sucks for sure but if man built it a man can take it apart and do it again! Don’t give up, let me know how things turn out
i left it alone for now since i only bought this car as a future project/toy but i am contemplating parking the car for a year and saving up to get an upgraded transmission or rebuild kit, it sucks for sure but if man built it a man can take it apart and do it again! Don’t give up, let me know how things turn out
Last edited by BetterDaze; Dec 20, 2025 at 09:50 AM.
