1992 500E won't upshift once warmed up

[cjscustomauto]

I recently bought a 1992 500E, love the car. It has 184k on it. Here's the problem I'm having. Once the car is warmed up, the transmission doesn't want to shift into 4th gear until its revving very high. Also it doesn't shift into 3rd leaving me only with 1st and 2nd gear sometimes. If the car is cold, it shifts fine through the gears. Reverse works perfect whether its hot or cold and the car only does this sometimes. It will also downshift from 3rd to 2nd for no reason. If its acting up and I put it in park at a light, then back into drive sometimes it will shift fine and go into 4th like it should. Some days it doesn't act up at all, I've driven it clear across town with no shift issues. I don't know what's going on maybe someone can help. I also noticed the fluid is kind of overfull on the dipstick but was going to take it to a shop for a transmission fluid and filter change. Any advice appreciated. Thanks

 

[gsxr]

Start with the fluid & filter change. Make sure it's a Mercedes repair shop that knows to drain BOTH the transmission pan AND the torque converter. It will take 8 quarts of fluid if both are drained and the filter is replaced. Also make sure they use Dexron-III rated fluid, not Dexron-VI. There's a decent possibility the problem may go away with fresh fluid, filter, and correct fluid level.

BTW - welcome to the forum!

 

[emerydc8]

Dave is probably right. After I took delivery of my 94 E420, the transmission was doing all kinds of weird things from not up-shifting to not even engaging. I was sure the transmission was toast. But I decided to change the fluid and filter and add a bottle of the Lucas stop slip. That was about three years ago. The problem has never returned. I'm thinking that something was clogging the valve body, but will probably never know for sure.

By the way, if you are going to take your car to a non-Mercedes mechanic, I would make sure they don't overtorque the transmission pan bolts, which is easy to do (the manual specifies 8Nm for the pan bolts, 14Nm for drain plugs). I would even be concerned about them using a non-Mercedes pan gasket like Victor Reinz or some other cheap knockoff. In fact, I wouldn't let a non-Mercedes mechanic touch my car at all, even to change the fluids. Welcome to the forum.

 

[cjscustomauto]

Here in Tucson there are a number of Mercedes-Benz specialty shops, so I'd trust they'd do the work right. I usually repair my own cars, but I'm not crazy about getting trans fluid on everything and disposal of the fluid. I did notice my trans seems over full. I bought my car from the 2nd owner who claimed he was an aircraft mechanic but he only had it a year and put 9,000 miles on it. He claimed all he did was change the oil and a ball joint that broke which caused the front tire to roll the front fender out a little. My friend said it can't he anything too serious otherwise it just wouldn't shift into the gears altogether. I'm going to go ahead and get it serviced, will report back with my findings. Also my friend mentioned I could have a bad ground.

 

[gsxr]

Oh wow, you're in luck... if you live near Tucson, I'd recommend going to Group One Motorwerks:

http://grouponemotorwerks.com/

The shop owner (Bart) has owned several 124.036's and definitely knows what he's doing on these cars. Strange about the broken ball joint, hopefully the fender damage isn't too bad. Maybe you could post up some photos of your new ride? You can start a thread in the "Owners" section. On a side note, these transmissions are fully mechanical, it's not possible for a "bad ground" to cause the symptoms you describe.

 

[cjscustomauto]

I actually talked to Bart, I was calling the Mercedes shops and he told me he has an e60 so I was thinking that would be the best place to take it since he is familiar with the e class in particular. Thanks for the advice, I really hope this corrects the problem I am having because I really like the car.