Has anyone had any dealings with or any knowledge of the Merc 722.6 5 speed auto box thats fitted to jeep grand cherokees and pretty much every merc from about 98 to 06?
got a slight issue with the one in the jeep. and being a porridge box virgin i dont really know what to be looking at
Main problem is two fold - and one of them being kinda important.
1 - when cold it feels very slow to engage drive and when setting off it just kinda draaaags. maybe 30 seconds later and its fine.
2 - when it fully up to temp and working hard - eg dragging the caravan down the motorway or high speed motorway driving - when you get off the motorway and start doing normal stop start driving, you frequently get the engine management light pop up and it will go into limp mode and stick in 1st or 2nd gear. You cruise to a stop and and the MIL light goes out and pop it out of drive and back in and everything is fine for a bit, then it will do it again. Other times the MIL light comes on and goes away with no other symptoms. Once or twice during very high speed runs (only 70mph, honestly), the MIL light will go on the revs will jump from 2500rpm to 2750, light will go out and it goes back down to 2500....Only seems to do this after doing 'hard work' as well.
These boxes dont display error codes on the dash either - when you get the codes from the obd11 it just gives a generic "the gearbox has told me it had a problem" number 0702 and thats it. To get the proper codes you need to plug it in to a merc or jeep bit of kit and get raped a million quid for the privilege of reading the gearbox ecu directly.
Before i go for the dealership trouser down route - does anyone have any idea what might be causing this?
In my own mind I'm thinking oil level wrong, giving bad cold gearbox response and possibly overheating after working hard? Also true to form there is no dipstick on these merc boxes, just a cover saying dealership only so i have had to buy an aftermarket dipstick for it. Should be here next week.
they also only accept atf4+, would the wrong oil cause these problems?
cheers for any help,
Nick.