D8H 46A Transmission Pump

Good day all,

This started this winter....... Whenever I let my old D8H sit for over a month or so, the transmission lube pump (5M6701), located in front of your right foot in front of the floor boards, loses prime. This doesn't allow you to shift the transmission and worse yet, no lube is going to the transmission. I have to fill up the pump through the little plug on top, start the cat and bleed air bubbles and repeat about 2-3 times before the pump will grab and then it will be good again until we let the machine sit for a long period of time. The first time it happened, we had a gauge on the pump, it showed nothing for pressure, but when we did finally get it to grab, the pressure was in the higher end of the required pressure spectrum (I can't remember exactly what it was or what the specs are) that our service manual says is required.

What would be allowing this pump to lose it's prime?

Thanks for any help on this.

It may be a bad seal on the pump drive shaft. Look for any signs of oily wet spots on the tubes to the pump. Also check the seal under the magnetic screen cover.