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Dodge1939D11

Radiator cap

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Folks,

I am looking for a replacement radiator cap and the one I have (Everseal R-3) on my 1939 dodge luxury liner. The cap I have comes up as a zero pressure cap when I do a search - does this mean there is no pressure in the cooling system?

Sincerely,

Confused and in Hot Water....

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Benefits of AACA Membership.

Yes. These are low or no pressure systems. There is no recovery tank. They do have the ability to run overflow in a tube down the side of the radiator but that's about it.

These systems will develop a bit of pressure just like any closed vessel holding near boiling water will, but as I am told, is not a pressure system. I am not sure when the move to pressurized systems was for Dodge but if you are using an R-3 and have no overflow tank the '39 is not a pressure system. It is like my '36's.

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1936 D2 Very interesting.

So I have noticed that as I have the engine running a very fine drip coming out of the overflow tube. The engine does not run hot but I end up putting about 1/2 can of coolant into it after driving about 40 miles. I can not see any leaks anywhere (I had one very minor seepage that I corrected with the proper application of a screwdriver to hose clamp)

Is this normal or do I have an issue someplace?

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Typically there would be roughly 7 pounds or less pressure within the cooling system, this is caused in part from the expansion, your rad cap does not sound like it is working properly, even though they come up as you say as no pressure again there is minimal pressure which the cap should be keeping in check.

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Normally your coolant level should be to the level of the top radiator hose. If you overfill above this you will have coolant leakage out the overflow pipe. There will also be some coolant loss in normal driving in any open non-pressurized system and don't worry too much about that if it's not much, just keep topping up to the hose level. You say you lose about a 1/2 can of coolant over 40 miles but you don't say how big the can is. How much volume are you actually losing? If it's a lot you may have just a hose leak or a loose clamp (double check them all) rather than something more serious like a radiator leak. See if there's a water pump leak which should be a fairly easy fix.

Edited by Bill Miller (see edit history)

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Right around 1/2 a gallon which seems like a lot. I will check all the places you mentioned, but I have not seen any leaks as of yet. I wonder if my temp gauge is stuck and the thermostat is sticking. It does not boil over which is confusing.

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Found a leak in the water pump from the weep hole. Odd thing is that it does not do it when the engine is running. Once the engine stops, there is a class II leak (army speak there) which is what drains the radiator.

I am assuming this is not normal.

Is it easy to rebuild a water pump?

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Found a leak in the water pump from the weep hole. Odd thing is that it does not do it when the engine is running. Once the engine stops, there is a class II leak (army speak there) which is what drains the radiator.

I am assuming this is not normal.

Is it easy to rebuild a water pump?

Everything is easy once you have done it once or twice. I am sure you can handle it though

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I do not know much about the later stuff but I am always reading Andy Bernbaum, also that the earlier units were re-designed but basically unchanged for a very long time so maybe that applies in your case and you can find a good part number of a kit still avail.

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I was very happy with

Flying Dutchman Pump Rebuilders

200 Davis Creek Road Selma, OR 97538

They were easy to deal with, had fast service and replace the old style packing with new, modern seals.

Before

IMG_1975_zpscafc7dc0.jpg

After, with new shaft, new modern seal and a new impeller

IMG_2443_zpsd30ea833.jpg

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I don't know what sort of seals your water pump uses on the '39, but I had a leak on my '15 DB water pump which tightening of the gland nuts on either end would not stop. It turned out the old string-type seals were shot so I just bought several feet of new string seal and wound it on myself, retightened the nuts (don't over-do it) and all is well. You can't get this stuff from PEP Boys or NAPA, etc. They just look at you like you are crazy. If this is what you use you can get it in several thicknesses from Restoration Supply by the foot and also I think from Tom and Cindy Myers.

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Or a good marine or boat parts supplier.

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Here are some tidbits on the radiator cap...

post-67404-14314219501_thumb.jpg

The first shot is a list of applications for the R-3 and R-4 caps. The second shot is a Zinc R-3 cap and the third shot is a Chrome R-3 cap.

post-67404-143142195007_thumb.jpg

post-67404-143142195009_thumb.jpg

Edited by 1936 D2
Corrected cap number data (see edit history)

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