722.6 Trans Slipping Code 147 - PeachParts Mercedes-Benz Forum

Roncallo · #1 10-01-2008, 10:01 PM

While driving I did hear and feel what sounded like transmission slipping generally on moderate acceleration from about 30mph. Sounds like a groan and you can feel vibration. Scan later revealed a code 147 which confirms slipping.

OK so I have a slipping trans. Ive done a search and it appears that there are many things wrong with the 1996 version of the 722.6 trans. Some are very simple alike a $3.00 spring etc.

I would like to know what can be corrected with the trans in the car. What should I try before pulling the transmission out of the car for overhaul.

This trans is out of a 1996 SL600 with 46,000 miles. I have also erased the adaptation values recently. Can that be causing it to slip as it re-adapts.

I dont have a thermocouple but the fluid level has been adjusted so that the highest it gets it just to the top of the 80°C range when hot and fully warmed up.

vince · #2 10-02-2008, 07:49 AM

The groan and vibration could be caused by the torque converter lockup clutch. It seems to happen more when the transmission is cold. The dealer did a software update on my 2000 C280 and it helped quite a bit.

Roncallo · #3 10-02-2008, 06:59 PM

Quote:

Originally Posted by vince

The groan and vibration could be caused by the torque converter lockup clutch. It seems to happen more when the transmission is cold. The dealer did a software update on my 2000 C280 and it helped quite a bit.

That is why I thought it was a clutch. It sound just like the torque converter clutch in my F150 when it went bad but it occurs when the converter should not be locked up so I believe it is some other clutch. I got my ATSG manual today so I will have a good idea of how this thing works shortly. I can already see they had about 4 valve body changes in 1996 alone. Mine is a late 95 production date so that apeares to be troublesome. So there appear to be issues. My reading through the threads points to a new conductor plate.

vince · #4 10-02-2008, 07:18 PM

Don't confuse the 722.6 with the Ford transmission (I've had both). The 722.6 converter clutch is programmed to engage in all gears and is also programmed to operate with a measured degree of slip.

Mine would groan at speeds between 30 and 40, especially if I let off the throttle and got back on the throttle.

The 722.6 doesn't have a valve body in the sense that the old M-B transmissions did either. They don't even call it a valve body anymore (and it is a lot less expensive). They call it a valve gear and it is basically a way to port fluid from the solenoid valves to the clutch packs.

Roncallo · #5 10-02-2008, 08:05 PM

Quote:

Originally Posted by vince

Don't confuse the 722.6 with the Ford transmission (I've had both). The 722.6 converter clutch is programmed to engage in all gears and is also programmed to operate with a measured degree of slip.

Mine would groan at speeds between 30 and 40, especially if I let off the throttle and got back on the throttle.

The 722.6 doesn't have a valve body in the sense that the old M-B transmissions did either. They don't even call it a valve body anymore (and it is a lot less expensive). They call it a valve gear and it is basically a way to port fluid from the solenoid valves to the clutch packs.

A converter clutch wont give you a Code 147 or 51. I need to get some live data out of this thing.

Roncallo · #6 10-04-2008, 07:18 PM

I believe I have isolated my problem to be caused by the wrong rear axle ratio. See the link below. I'm still not sure why it vibrated under load. But I have the shifting understood. The vibration may be a torque converter

M120 into 560SL (With Pictures!)

Thank you everyone