gmc radiator pressure valve fix.

[54 jimmy]

ok so i have been searching for a replacement pressure valve for my gmc radiator. my rad is good and i plan on using it im my s10 swap truck. so here it goes. first you need to get a 16 lb rad cap fo a chevy. seaond drill out the top peaned parts of the cap to release the pressure valve. third make sure the overflow tude does not protrude and catch the valve. don't forget to get a new gasket for the plug. and finally reassamble everything and good to go. well i hope. all the parts to this fix cost me a wopping five bucks. beats buying a new radiator for a few hundred for our gmc trucks as they are a little difficult to find certian parts for.

[54 jimmy]

more pics

[Dan Bowles]

I don't know what motor you are planning to run on your truck but we had the top hose neck replaced on our stock Chevy radiator to a larger diameter when we did the S10/327 swap in my son's '54. The guy tanked it, changed the top neck, and painted it for $60. To go with your fix, that's a pretty cheap swap.

[54 jimmy]

dan thanks for the info but my truck was a one ton with the bigger inline6 so the nech on for the top hose is the right size for my app.

[Klorne]

I know this is a really old post, but it's something I'm considering doing to my radiator. Can you tell me if this fix will operate as a 2 way valve? In other words, if run the hose to an overflow tank, will it pull coolant back into the rad if needed? I cannot find any info on these old radiators online, so I'm hoping someone can help me out with this.

Thanks,
Kevin.

[mr48chev]

It's always best to start your own new thread than tack a question on the end of a 13 year dead thread. Folks will toss out an answer to the first post and never scroll down the page to see what you asked.

One thing, these old radiators and heater cores will handle 4 to 7 lbs pressure max before they fail. Add in that a 70 year old radiator has a lot bigger chance of failing. Even 7 lbs is pushing the limit.