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Topic: Radiator Caps (Read 576 times) previous topic - next topic

Radiator Caps

I played with my cars a little this weekend getting them ready for weekend duty and ran into trouble with my mustang puking out the overflow after i shut it off. Combination of overfilled(i forgot i topped it off months ago and wasnt supposed to) and a bad radiator cap after taking it out and inspecting the seal. No big deal and i lucked out and ordered the same one for it a nos Motorcraft RS-60, which was lucky to find.
Then i thought about the Thunderbirds radiator cap and cooling system and i havent really checked anything out on it other than level, so i went down to look at it.
Everything is fine but i want to flush it and replace my radiator cap on the thunderbird as a precaution anyway since i have no temp gauge on it just an idiot light, but not sure about something so bear with me if this sounds stupid.

The cap currently on it is a Motorcraft RS-51 #16lbs, i dont know if thats original or not to it, and i cant find the same one. Im trying to stick with period stock parts and there are a couple RS-50 and RS-53 floating around but even though they are both the same #16lbs i dont know if they physically fit.

So first, Is the RS-51 correct for my car in the first place?
Second, since i cant find that will the others mentioned fit?

I dont want to just go get a parts store brand cheapie one if i can still get nos period oem parts if i dont have to.
"Beating the hell out of other peoples cars since 1999"
1983 Ford Thunderbird Heritage
1984 Ford Mustang GT Turbo Convertible

Re: Radiator Caps

Reply #1
No idea what came on it originally. Specified pressure in my '87 FSM is 16 psi.

Looking at the Gates interchange page - https://ww2.gates.com/if/automotive/partslookup/Interchange/index.cfm - the RS-50 interchanges to 31527 and the RS-51/53/60 all interchange to 31528.

The 31527 has identical specifications to the 31528 except for the operating pressure.
31527 is 13 psi and
31528 is 16 psi.
Both will fit your car.

https://www.gates.com/us/en/other-products/caps-and-thermostats/radiator-caps.p.7410-000000-000012.v.7410-00225.html
https://www.gates.com/us/en/other-products/caps-and-thermostats/radiator-caps.p.7410-000000-000012.v.7410-00226.html

Re: Radiator Caps

Reply #2
I guess "technically" fitment isnt an issue between them just #lbs rating.
Its weird because im sure i saw the rs-50 with a #16 stamp on it.
Ill grab an rs-53 and pick up some coolant next time i have a chance then.
"Beating the hell out of other peoples cars since 1999"
1983 Ford Thunderbird Heritage
1984 Ford Mustang GT Turbo Convertible