with help from Pete's wirte up I got my aux pump working

I found that the previous owner had disconnected the wiring from the aux pump. But the heater still worked.

I found that the design of the aux pump allow coolant to flow through the pump even without it running. Apparently the mono valve must also be open for this to happen. I guess the design allows the heater to still work to some extent if the pump fails.

Anyway, I removed the pump and removed the two tiny, but long screws at the rear of the motor. I carefully worked the cover off the motor. The brushes and all stay put so no worries there.

I found some rust inside. I guess over the years water seeps inside the motor cover from washing the engine and such. I hope it was not from the shaft seal leaking.

I used a brass brush to clean up some of the loose rust and corrosion. The motor did not spin freely. When I applied power I could feel it wanting to turn but it would not more. I sprayed it with a little PB Blaster, but any spray lube should work just as well. The lube freed up the motor shaft very nicely.

I put the motor cover back on and ran the motor a few times to let the brushes clean up the commutator? Removed the cover and added some more spray lube.

Put it all back together and we will se how long it lasts.

I'm guessing you should run the heater regularly, just like the AC. Even when it's summer. That would keep the motor and monovalve from sticking or freezing from no-use.

__________________
1987 300TDT
1981 VW MKI Caddy 1.6 diesel, waiting on engine swap
1983 D-50 Power Ram 4x4 "Mitsubishi" 2.3 turbo diesel
assorted gas powered crap and motorcycles

RIP: 1984 300TDT, 1982 300TDT, 1984 190D 2.2, 1992 300D 2.5, 1987 300TDT, 1982 Maxima LD28, 1983 Maxima LD28, Isuzu C223 P'ups X3, 1983 Holiday Rambler 6.2 Banks turbo diesel, 1984 Winnebago LeSharo 2.1 TD, 1985 Allegro 6.5