The Stovebolt Site Forums The Shop Area Engine Shop 261 water pump

I am replacing my water pump and the new one I purchased has a small hole at the top left looking from the front that intersects with a hole in the block. The old pump didn't have this hole,which one is correct?another question I have is the water pump has 2 - 3/4 inch hose fittings and the thermo housing has one,I realize 2 of these go to the Heater circuit but what about the third one,the cylinder head was off when I purchased the truck,and I didn't see how it was plumbed.

This is a '59 261 pump and thermostat hsg. I don't know which
truck or bus this came out of so can't tell you the routing
of the hoses.
http://www.pbase.com/dennygraham/image/161809621/large

dg

Denny,

Have you checked the operation of the thermostat (a Dole pellet by-pass thermostat was originally used, I think)?

GMC kid 7530,

My 1960 261's water pump (from a school bus) did not look like Denny's. It had an extra port (or two); and, the thermostat housing had a port on the bottom, like Denny's.

Years ago, someone posted the purpose for those ports (sqeeze or 3B or Mike B?) - a by-pass hose. I wildly guessed they were for a heater at the rear of the bus (or, maybe for a transmission warmer/cooler).

Maybe someone will post an answer?

You may plug the holes if they are not used (mine were plugged with hex-head steel plugs).

Years ago, I used a smaller truck's water pump and thermostat housing, to better match my 1954 radiator. Today, I use a water pump relocation plate and a 54 water pump and thermostat housing.

Denny, I believe the GMC 228 had this type of water pump set-up.

Not quite:
http://www.pbase.com/dennygraham/image/161813564

dg