I've lived with this problem for about five years now and I'm trying to figure out if it can be fixed without pulling the transmission out. The transmission is leaking, but it's very difficult to tell where it's coming from, because it's closer to the top (probably more from the passenger side) and I can't actualy see where it's leaking from. I can always tell when it's time to add more fluid because the engine RPM will surge for less than a second when it shifts from second to third gear. The higer the load, the more it will surge.

When I check the fluid level after this occurs, it's always slightly below the full line. Adding about 1/4 to 1/2 quart of fluid always fixes the surging problem for about 200-300 miles, then it starts again. If I add more, it seems to leak out at a faster rate, down to about the half-way mark on the stick, then the leaking tapers off to a slower leak.

Other than the surging RPM, the transmission does not slip at all (I'm not even sure that the RPM surge is cause by a slipping). When the fluid level is correct, it shifts as hard as the day I bought it. When it had 175,000 miles (54,000 miles back), I talked to an MB tech about the problem and he said that the oil pump seal is a common failure on the 124, which would require that the transmission be completely removed. However, I did see a post about a B1 cover that is a common source of leaking on these cars. Any input woud be appreciated. Thanks.

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles