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1924 Model 41 With Foamy Coolant


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Hello all,

Just got my 24-41 up and running again after 6 years of sitting. It is GREAT to have it running again. Had many fuel issues to overcome but that's all settled now.

This foamy coolant thing is not a new problem. After a good run the coolant has a thick foam on it. Some will go out the overflow tube and make a foamy puddle on the ground or along the road. It's not a dirty foam as you might get with a bad head gasket. It's clean and coolant colored.

My theory is that the water pump is either sucking air at one or both of the packing glands or that the pump is cavitating. It actually leads to somewhat low coolant levels so I would like to do something about it. Has anyone else had this problem and, if so, how did you solve it? Additives? I currently use a 50/50 mix of water & Prestone.

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Hi- on culprit on such a foam issue is the grease used on the water pump shaft....on that era car you probably have a small grease cup reservoir, and you're supposed to turn the top every now and then to add more lube to the shaft...the lube also seals the shaft and prevents air getting sucked into the pump....it has to be the heavy water pump grease, with the right properties of water resistance, not any regular light grease......just one place to be looking...

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Most often, this problem is caused by an old collapsed hose on the suction side of the pump which causes cavitation and results in foaming. Be sure to replace the old hose with one that has a spiral wire to keep it from collapsing when it gets hot.

As previously mentioned, leaking packing can also cause this. Replacing the packing with graphite impregnated braided packing minimizes the need for water pump grease. Just adding more grease that will eventually coat the radiator core is not recommended. Be sure to check the condition of the water pump shaft for pitting before installing new packing too. A new or dressed up shaft will also minimize the need for adding grease.

My 2 cents...

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The shaft was replaced several years ago. I believe we used stainless steel. It should still have a good surface. The packing however may be getting old and probably wasn't braided graphite. I have some of the braided graphite and will give it a try. Also will get some water pump grease and inspect the lower hose.

Let's not consider this solved yet, just in case anybody else has any more ideas.


Jerry Van

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