Radiator Cap Replacement
 

Hello All,

When I bought my 1934-35 REO Speed Wagon truck it did not come with a radiator cap. Does anyone have an idea what radiator pressure the cap would suit the truck's six cylinder "Gold Crown" motor?

Kind regards
Lionel

Lionel, I have no specific knowledge ( don't even know what the truck looks like) however it is probable that it was not even a pressure system in 1934.
At this point in my post, I did a little search, and found this:

The modern pressure cap The unsung hero of the modern vehicle cooling system must surely be John Karmazin of Harrison Radiators Division of General Motors in America. His invention was the radiator pressure cap which was first used in Buick cars in 1939, and has long since been taken for granted.

So, My guess was about right, that pressure systems came into being at the start of WWII. With G.M. behind it, the common standardized caps were the A.C. Delco types that you will be familiar with. My carrier has a design of cap that was a Ford thing specific to carriers, and before that there were valves that held pressure, but dumped the excess. the valves were fitted to the overflow pipe (1938 ish). If you think about the other M.V.s found on this forum, many were fitted with a catch tank that siphoned the water back into the rad when things cooled down.
I think your cap would have been made by the Rad manufacturer or by the truck manufacturer. Try setting up a search for one on ebay.
Good luck.

Hello Lynn,

Thank you for your detailed reply and for your extensive research. I greatly appreciate it.

Here is an internet photo of a same model REO Speed Wagon truck as mine accessed 28th March 2022 from, https://www.smartcycleguide.com/L49132542. The photo has the truck parked in a wooden barn.

Of course the photographed REO truck is in better condition than mine. Unlike the REO truck in the photo my truck sat in a paddock for 40 plus years after it was parked up by the previous owner's father. Since I have owned my truck it has been sitting patiently in my shed. By then the weather had not done my truck any favours though. The next photo is my REO parked beside its stable-mate, that is also waiting patiently in my shed for some attention. However, things like the white one keep usurping their place in the queue.

Notice that the wooden barn REO does not have a radiator cap either! Must be a common occurrence - leave a truck sitting for a while and someone nicks the radiator cap.

Kind regards
Lionel