Technical Correct grease for early flathead water pumps?

I am running a '36 flathead in my Model A pickup and noticed when adding some water last weekend that there was a thin layer of grease on the underside of my radiator cap. It dawned on me that it is coming from my water pumps. My understanding is that water pumps that could allow grease into the cooling system used a water soluble base that would not coat and clog the cooling system. Is there any grease in production today that meets that need? I really don't want to crap up my cooling system and I also don't want to drop $200 on rebuilds that may or may not be able to be serviced 10 years from now.

Aside from cost, another reason for my apprehension to have my pumps rebuilt with modern seals is that I have a very rare accessory right side pump that has heater hose connections. I don't want to modify this pump to the point that it can't be serviced when it eventually goes bad again.

I know that there is "water pump grease" for sale from various vendors but it is advertised as water proof lubricant that will not dissolve in water. This is exactly what I don't want. Any suggestions?

 

I can understand your concerns but that water pump was designed and used for years for the very reason that it is not water soluble. That grease will eventually possibly clog your radiator and affect the cooling capacity. However any water soluble grease would wash away very fast and eliminate the lubrication provided. Your packing also holds in the coolant and for grease to get past it could be an indication that it needs replaced.

 

Look for some of this.

 

Or this

 

Actually, early flathead pumps have a mechanical seal that prevents water from getting into the bushings and grease cavity. Packing isn’t used. When you grease one of these pumps it has a fill hole and an exit hole (on most) so that you don’t pump grease past the seal or crack the cast housing. Regular running of the pumps does allow grease to work into the inner bushing and past the seal though, thus the problem.

 

Not sure if I’m on the right page as regards what you’re asking:
A top flat head expert here once told me to put a cup of water soluble oil in the radiator to help lubricate the original water pumps.
Never heard anyone else mention it, but I followed his advice.
Would be interested in others comments.

 

Clem, your expert was probably talking about post '37 pumps. The early ones are built differently. Post '37 actually have a weep hole to bring engine oil to the bronze bushing.

 

^^^yes, that is what I have on my 8ba, cinted bronze bushings in pre ‘49 water pumps. But post ‘38
Thanks alchemy, you’re a wealth of information .

 

I am learning something here...I think. So, not wanting to hijack the thread, but I have a '48, so do I need to grease the water pumps?

 

Sure, just squirt it in the zerk on the front.


(There is no zerk. No way to "add" grease to a 38-48 water pump. Hopefully if they were rebuilt the builder cleaned the weep holes so the oil supplied by the engine will get to the bronze bushing.)