55 Dodge/Fargo/Desoto Radiator Cap

Hi all,

I have a 1955 DeSoto 671 truck with a 251 flathead six engine.

Does anyone know where I could get a radiator cap. Im having a problem finding a replacement Or a modern day equivalent that will suit?

Cheers
Anthony

Here is the Tridon list. A cap to suit will definitely be here but just have to find it from the part numbers.
www.tridon.com.au/databank/documents/CAT058-Automotive-Cap.pdf

REPCO should be able to match it for you if you take in a sample.

If you want to do a drawing and put it up with the dimensions I have a box of caps, some certainly Dodge, and you can have what you need.

I don't think it would be the end of the world if you had just a water splash stopper with no pressure on the Dodge 6. If you use nice rain water straight it is up to 30% more thermally efficient than stuff with additives. Additives increase the boiling point but it is not such a great advantage because they run hotter because they transfer heat much worse than straight water. In cold climates additives are essential to stop the water freezing but in Australia its main use is to stop corrosion, particularly on alloy engines. Many modern engines are designed to run normally so hot that plain water can not cope.

Just had a look at my Dodge manuals. Many Dodge, Plymouth, Desoto and Chrysler cars of the 40's with the flat 6 had zero pressure. The overflow came out under the cap from the radiator neck - they were just splash stoppers. The trucks had caps ranging from the above zero pressure to 5 psi with the overflow above the neck - the water had to push the cap up to escape. I think if you got a cap under 7psi you will not stress the radiator and achieve the aim of a higher boiling point. If the overflow comes out the neck below the cap like some Dodge cars and light trucks 1,000 psi will make no difference.

Your engine was designed for and probably did its first 50 years of life with just straight water. With a clean radiator they do run very cool normally 160-180 degrees in the old money so you have plenty of fat with no pressure before 212 degrees is reached. If it sits a lot a rust inhibitor is a good thing to stop the Dodge head water distribution tube rusting away, which they all do eventually.

Lang

This is the first time I have heard of another engine with a water distribution tube in the head. The only other was our David Brown Cropmaster tractor engine. It was rusted out but a new one made from stainless was made and fitted.

Sorry, not in the head, in the block to direct water over the valve stems.

All the flat 6 Chryslers had them from the 30's onward. Most people rebuilding these days fit copper or stainless tubes to solve the problem forever. I have owned and seen many Dodge vehicles, never restored, which on disassembly had absolutely no tube left and showing no sign of trouble. They are easy to get at just by taking off the water pump but getting a rusted unit out with a hooked tool can be fun even though they just sit loosely and slide in by hand when new. You will have to pull the radiator because the tubes are about 18" long.

They would not have fitted them if it was not necessary and I can see where there may be dead spots in the water flow requiring a directed stream around the valves.

Lang

The Cropmaster has an overhead valve engine hence it is in the head and as you mention directs cooler water onto the vavle stem area inside the water jackets.

Hi Lang/all,

Thanks for the info!

Where is the best place to buy parts like the water distribution tube?

Is there a good supplier of all things for the old Dodges etc?

Cheers
Anthony

I think the US Dodges had the big cap used on WW2 stuff......like the GMC 6x6.....

Here are a few

Water distribution tube and other parts
www.dodgeparts.com.au/?product=water-distribution-tube

www.ebaystores.com.au/Erics-Classic-Dodge-Truck-Parts

Ross Prince at Hervey Bay has lots of mechanical stuff NOS, new and repro. I bought a repro water pump off him a few months back amazingly cheaply and with modern bearings and seals. Ross should have the tubes as well.
0434744075

Vintage Power Wagons are fantastic and I have been dealing with them for 30 years. A great on-line catalog specialising in the Power Wagon family but most Dodge trucks used the same stuff.
www.vintagepowerwagons.com/

There are quite a few others around Australia.

Lang