In need of 401 v6 water pump

[nwdan]

Hello,
I am new here, and I hope this is the right place to find some answers. I have acquired a 1955 Kenworth Pacific bus with a 401 GMC V6. The only thing wrong with the bus is a water pump that has seized. After searching far and wide, I realized that no one seems to know where to find a new or rebuilt one. To make things worse, the shop that I gave the old pump to lost the original! I am screwed if I can't at least find another old one to have rebuilt. Please help.

-Dan

[WE7X]

Since it is a bus, is it a rear engine or front ?
I have a 1970 RM-7500 which is a rear motor (401M) school bus chassis, converted to an RV.
I had to replace a Water Pump many yeas ago, while on a trip east, and had some trouble finding the correct one. I had the old pump with me, so at least I had something to compare.
There were three options as I recall, and they all had to do with the length of the impeller shaft. All had the same bolt pattern, but I think the flange for the pulley was extended a bit on the one I needed.
I have the air brake pump setup on mine, and that may be the difference, even though the air pump belt does not run across the water pump pulley.
I have looked, but do ot see any record of a part number for that replacement pump i purchased.

Rod Johnson
Issaquah, WA

[nwdan]

Yes, it's a rear engine vehicle. It's just the 401 without the M though. Someone has to know where to get one, or possibly could sell me an old one, I hope.

[WE7X]

Dan,
I do not think the 'M' designation would make any difference for water pump, but the front cover for the bigger motors may a bit different. I think one puts the water pump higher on the motor, but don't quote me on that. I seem to recall a discussion some time ago; about when putting a motor from a larger series truck into a pickup, the front cover may have to be swapped out, for the water pump to be in the correct location for the cooling fan shroud on the radiator (on the smaller trucks). I may be hallucinating, but I seem to recall something like that. I do not know just what the difference is, or maybe it was related to the difference in timing gears vs. timing chains on the bigger motors....Again, don't quote me. <grin>
I have two 478's here, in the garage, with no belts on them, and the 401 in the motorhome. If it comes to that, since you are fairly close to me, you could 'borrow' one of my water pumps to try, and then get one to match it. It comes off without disturbing the housing (6 bolts or 8?) , so it would not be much trouble.
Rod Johnson
Issaquah

[nwdan]

If I can't come up with another one, I would not mind trying one from a spare engine if you have one. If it fits, I might have more options on potential vehicles to pull a pump from. I see a 305 on craigslist in maple valley for only $60, but I don't know if the pump will fit.

Also I need to move my bus to a spot for the winter, only a half mile, but I have to install the pump and pulley to move it. Maybe I could use one of yours for a day if it fits? Thanks for the info.

-Dan

[abus319]

Dan
I looked at the "known part number" section of Jollys page and got NAPA 55-835.
That didn't show up on NAPA's website but a Google search came up with the following cross reference numbers;
Gates 42099, GMP 130-2835, ASC WP 371, Borg Warner P450, and Carquest 51-1513.
I looked at the rendering of the Gates and it looked like the 305 pump so Im not sure if its the correct pump, but might be a place to start.

[tommr]

nwdan. is your bus air brake equipped? the air brake equipped 401 has a threaded pump shaft with a cast iron pulley. those pumps are available. thx

[tommr]

Our 47 has air brakes and the 401.

[ilvracn]

Tommr do you have the part # sounds like the pump on my v-12

[nwdan]

WE7X: The part number you gave me for napa is correct: 59-8146. They don't have one anywhere in the nation though, so I'll need a core to send in to be rebuilt. Now I have to find one in a junkyard.

tommr: Do you know of another place that might have one?