MTFCA Forum

Should there be a rubber gasket under the radiator cap?

A Ford stock radiator cap?

Yes

Ford part #3927

It was a paper gasket, I believe - not rubber. If you have a motometer or a decorative cap, one could use a rubber gasket or an o-ring to assist in the proper alignment.

Or stop at your local hardware store, even the big box store, and get a drain gasket.

The problem is the thin edge on the original radiator cap. When you screw the cap down, that thin edge engages right on the outside of any gasket used, and often the gasket is distorted and the cap doesn't seal anyway. If you can find one of the caps with the rolled in edge below the thread, you are on a winner.

I make my own, cut off the end of a red urethane boat trailer roller. They end up about 1/8" thick, have a smaller hole in the middle and thus do not so easily distort. My little finger pulls it out if ever I need to top up the radiator.

Allan from down under.

Yes gasket, of some kind. unless you like cleaning the hood & windshield. Or goggles if you have Speedster.
Craig

Paper gaskets are rubbish. I use (and love) Part # 3927M from Lang’s.
It’s nice n thick, rounded end that fits nicely into the Radiator Neck, made of Neoprene and cost $1.65. Bargain.
As suggested by others it has a bit of compression to align the Cap or fancy wings or temperature gauges!
Easily flicked out when coolant topping up is needed. Get a couple
Alan in Western Australia

Old thread suggest using a popup drain gasket as it is the same as sold by vendors and available in most hardware & ome Improvement stores
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