Packard Forum Index » Pre-War (1899-1942)

The back plate does not match mine.

After cleaning the plate up a little, it appears the hole was "brazed" over a bit.




Shouldn't be a problem closing that hole up and drilling another one that lines up with the plate. RIGHT?

I would think that would work. I know when I bought a "new" water pump, it came with a new back plate and gasket. I bought my pump through Patrician Industries. As an alternative, you might reach out to them to get a new backplate.

Thanks

Thanks to all for the help. I believe I have finally figured out what I have.
My '37 coupe had a '47 engine with a '37 pump that had a '47 plate on the back. The bypass holes don't line up

That plate is definitely different than mine. I put a new Kanter water pump on my car, and it's worked well for about 5,000 miles now. I have a spare that I rebuilt from parts I got from David Flack. The new pump looks identical to the original.

I wonder why they changed the block location and maybe size of the bypass on later blocks. 37 and 47 model radiators are approximately the same shape and size so unlike later models with lower radiators (and a different block), the pump and fans on the earlier models would be in about the same location. Not entirely sure of the reasons a bypass is present or remember the path thru the pump unless it is to help air get out of the system. If that is the purpose perhaps the changed bypass size and location allowed a better escape path but if there is another purpose would love to know opinions..

The 1938 cooling system was much improved, with a ball bearing, mechanical seal water pump and a pressure cap. I think the 1938 pump had a larger shaft. I suspect the '38 pump had a higher capacity at lower engine speeds. The bypass port in the block and pump allowed some coolant circulation in the engine to promote more uniform warm-up when the thermostat was closed and prevent heat buildup around the exhaust ports. It also allowed trapped air to escape when refilling the system.

The 1937 water pump has a 1/4" bypass from the pump discharge into the engine block, above and outside of the water tube. There is a 1/8" bypass in the pump casting between the pump inlet and the pump discharge. I don't know if the original spec thermostats had a bypass port in them.

I have ordered a new one from Kanter. I was told they are updated with modern seals and bearings. I still have a long way to go so I will start my next topic.
Delivery is July 2025.