Radiator cap too tight to fit

[johnbuckley]

Got a Macs replacement radiator cap from our agent here in the UK (twist on type for '31 model) . Can't fit it as the lugs are pressed up too much and there is insufficient "give" of the fibre gasket to get it twisted onto the neck. Is this just a rogue cap or has anybody else had the same problem? Any thoughts on how to get it to fit- can't access a file under the lip of the cap lugs and don't want to file the fitting on the rad neck.

 

[Louis]

John,
I had the same problem with my 31, The new gasket was my problem, I just forced my cap down and twisted it enough to get it started then drove it and got it hot and tightened agin, I had to push down very hard as I twisted the cap, it will take a few try's but it will fit. good luck .
Allso clean the the rad. neck to where it is smooth. might even put a small amount of lub. on it to help.

 

[700rpm]

If you have a repro radiator the neck could be incorrect. I have a NOS cap on my 31 pickup, but a repro radiator, and the cap is a tough nut to crack. I just muscle it anyway, because I figure the difficulty will discourage people from trying to take it off when I'm not looking.

 

[Tom Wesenberg]

I would pour hot water on the cap and gasket and try it as Louis mentioned.

If it was the same problem for a gas cap I would put oil on the gasket.

 

[johnbuckley]

Thanks for those really useful tips, guys. Much appreciated.