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Slow Shifting Mercedes

My MB E320 shifts slowly when I first start the car in the morning. Seems engine temperature has to reach near the middle of the gauge before the transmission will shift from 2nd to 3rd and above. After it shifts it will be fine for the rest of the day, as long as the engine temperature remains in the middle range of the gauge.

What year??? How many miles??? How often has it been serviced??? Hows the fluid level and condition??


1997, 153k, the transmission filter was changed earlier this year. The fluids then were checked and in good condition, according to the dealer, a MB dealership. Thanks for helping.

Sounds like the classic Mercedes “Morning Sickness”. It’s very common with MB transmission designs. “Morning Sickness” is usually caused by leaking seals and it’s a function of age.

First off, any automatic with 150,000 miles or more on it owes you nothing—when it starts acting strangely, and has clean oil in it, it’s overhaul time.

Secondly, leaking around the front seal, rear seal, and piston cap seals says that all of the rubber in the box is hard and deteriorating.

The best bet, if you’re wanting to keep the car for another 150,000 miles, is to install a factory rebuild available through any MB dealer. It comes with a factory warranty, meaning Mercedes themselves stand behind it.

In the long run it’s much cheaper than buying a new car.


With the age and mileage it certainly does sound like the clutch piston seals have hardened and are leaking. This is a very common ocurrance in any automatic transmission. Rubber clutch piston seals harden with age and when hydraulic pressure is applied to it to apply a clutch, the fluid passes by the seal causing late shifting and even a no shifting condition. When the transmission is cold the symptoms are worse. As the trans warms up, the seals soften and will seal better. This is why when cold, your problem is worse. Unfortunately the only permanent cure for this problem is overhaul. Nothing too special about these. They are pretty basic to overhaul. The master kits are expensive but not too bad. If hardened seals are the problem here you can get away with pouring a can of Berrymans B-12 Chemtool in the trans. This stuff will soften the seals and help shift the transmission. Its also good for keeping the transmission and valve body clean. Try this first. I have had customers use this for many months with no problems. I used it myself on my own transmission for several months until I could find the time to rebuild it.


Heres what to get: Pour 1 can down the dipstick tube, run the gear selector through all the gears and drive it. The real test will be in the morning. Let us know what happens.