There is a service bulletin from ATSG about delayed engagement of forward gears after replacing the B2 seals. If you installed the new style seal on an old style piston, this could be part of your problem.

If your gearbox is from 1981, chances are you have (or had) the old style B2 piston. Did you replace it with the new style? Did you install the new style B2 piston guide?

Do you have any engagement at all of forward gears?

I'm not sure if it's possible to install the B2 piston without a properly seated thrust pin...... If so, that might explain no engagement. I can't remember for sure, but I think it is possible to see the pin from below if you remove the filter from the valve body.

I'm not an expert, but I would think a longer thrust pin would only help solve a slipping problem

Do a search, there is a link to the ATSG document somewhere on this forum. When you find it check out page 109.


"I'm a hobbiest DIY mechanic, not a professional tech. Evaluate my comments accordingly..."


J. M. van Swaay

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1994 E320 Wagon, 230,000 miles
1995 E320 Sedan, 106,000 miles
1994 E500 Sedan, 79,000 miles