What you are describing is a lack of positive engagement of the unit once it warms up a little. You may also find that it engages OK at higher speeds, but not, say, below 50 or 60MPH. First check the fluid level. Low fluid can give these symptoms. If fluid level is OK, it's probably leaking seals in thehydraulics. What I did was drain and refill with Redline MTL...expensive at $9/qt, but the OD has behaved much better for 6 years and 60k mi now.

Otherwise it may be time for an overdrive seal kit to repair the leaky piston seals you undoubtedly have. Duane ("OD Guru") hasn't been seen on this BB for a while - he used to sell these parts at a good price and offer detailed expertise on installation.
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Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar MGB, and numerous old motorcycles)

Don't have a solution, but my OD also works well for the first 3 times using it (does that nice *bump* and smoothout) but then gives me a big vibration before dropping down, or else it doesn't catch at all, so I turn it off.

I changed the (manual) transmission fluid to Amsoil last month but I did not service the OD unit itself.



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__Stef; 81 DL wagon B21A SU carb M46 __313k