Hi.
Sorry about intruding here, with the wrong car!
But since my problem is about the 5-speed gearbox (55 & 65 that is), I thought I would increase my chanses of response by writing here also.

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 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

Changing trans fluid should be standard procedure for any new (used) car, it makes a difference.
The transmission connector on these transmissions will fail, allowing fluid into your conductor plate. Once this happens the transmission will start acting odd, and you'll get codes relating to "gear ratio implausible." This is because the trans fluid gets into the conductor plate and kills the electronics.

I'd replace the conductor plate, transmission connector, and add fluid to see what happens.

If the connector has been bad long enough, oil will wick up the wires into your transmission controller, which may or may not damage it. You'll be able to look and tell immediately by discconnecting the module and seeing if the plug is oily. If so, take the module out and turn it upside down, a bunch of oil may come out. Had that once, so I sprayed it down with Electronic cleaner spray and replaced the above 2 parts, no more issues.

Also, low fluid will make the transmission kind of behave in the way you describe sometimes.

I can now inform you guys that the flush did not help one bit.

probably conductor plate then, it's a known failure point if fluid leaks in. The speed sensor housed on the plate can also just go bad sometimes. Pretty easy replacement. Had to do that on my '55. The transmission in mine died at 150k miles, but I have a limited slip differential and abused it constantly.