Radiator cap leaks on my 1960

[Donald H.]

I have a DeWitt 55M direct replacement radiator in my 1960. It is their aluminum reproduction of the copper radiator (Early 60 and earlier). It is not the later tank top radiator.

I bought a reproduction 7# AC cap, which leaks around the filler. Looks like I will use it only for judging. I know it isn't correct as an original, but I have assumed it will judge better than a auto supply replacement cap.

I am going to get an auto supply Stant cap to use for normal driving. I am ordered a GM cap that Joe Lucia recommended, but when I looked up the part number it says it is a 15# cap.

My question is, should I get a 7# cap or use the GM 15# cap? I assume with a 13# or 15# cap, the engine would get a lot hotter before it would release pressure. Other than that, is there any problem with running with a higher pressure cap?

Thanks,

DOn

[Terry D.]

Re: Radiator cap leaks on my 1960

Did you have the cap tested? Does it leak or is the system building up more than 7 lbs of pressure? What kind of temperature is the engine at when it leaks? Did you ask DeWitts what cap they would use on their rad? Terry

[Donald H.]

Re: Radiator cap leaks on my 1960

[QUOTE=Terry Deusterman (11486);659011]Did you have the cap tested? Does it leak or is the system building up more than 7 lbs of pressure? What kind of temperature is the engine at when it leaks? Did you ask DeWitts what cap they would use on their rad? Terry[/261184740044 is correct. Kevin 775

The engine runs very cool. Tested with and infrared thermometer and the rad hose and thermostat housing is 150 degrees. The cap just doesn't feel like it seats good. I did send DeWitt and email today, so I will not hear until tomorrow or later from them.

[Joe L.]

Re: Radiator cap leaks on my 1960

I have a DeWitt 55M direct replacement radiator in my 1960. It is their aluminum reproduction of the copper radiator (Early 60 and earlier). It is not the later tank top radiator.

I bought a reproduction 7# AC cap, which leaks around the filler. Looks like I will use it only for judging. I know it isn't correct as an original, but I have assumed it will judge better than a auto supply replacement cap.

I am going to get an auto supply Stant cap to use for normal driving. I am ordered a GM cap that Joe Lucia recommended, but when I looked up the part number it says it is a 15# cap.

My question is, should I get a 7# cap or use the GM 15# cap? I assume with a 13# or 15# cap, the engine would get a lot hotter before it would release pressure. Other than that, is there any problem with running with a higher pressure cap?

Thanks,

DOn

Don-----


The radiator cap which GM specifies for your application is a GM #850795. The information I have is that this is a 7 LB release cap. However, whether it is or isn't, it's the one that GM currently specifies and approves for your application. However, keep in mind that this is a cap designed for use with a COPPER/BRASS radiator. As far as I know, GM never offered a cap of 7 LB release for aluminum radiators. Caps for aluminum radiators have special features to minimize galvanic corrosion.

I think it would be perfectly OK for you to use a 15 LB RC-26 cap which is designed for use with aluminum radiators (but can also be used with copper/brass radiators). Basically, your cooling system, especially now with the DeWitts aluminum radiator, is no different than systems originally using a 15 LB cap. The higher pressure system will probably actually be a benefit.

[Donald H.]

Re: Radiator cap leaks on my 1960

Joe, I went ahead and ordered the GM 6410206 cap, which I saw you had recommended in another thread.

I did solve my problem for the interim. I borrowed a tester and found that the repro 7# cap would only hold 4#. i bought a 7# Stant cap at NAPA and it holds a solid 7#, so until I get the GM cap, I will just use the NAPA cap. I was able to bend the ears on the repro that hold the cap on inward enough to create a better seal and get it to hold higher pressure, but not that I would trust for much.

[Joe M.]

Re: Radiator cap leaks on my 1960

Donald, use the aftermarket cap until you are finished with Ops, once you get your car parked inside for judging, switch out the cap.

[Donald H.]

Re: Radiator cap leaks on my 1960

Donald, use the aftermarket cap until you are finished with Ops, once you get your car parked inside for judging, switch out the cap.

I think the judging is outside, so will I have a chance to switch the caps? As I recall at Kissimmee they when directly from Ops to the other areas of judgin.

Don

[Joe M.]

Re: Radiator cap leaks on my 1960

I can't answer that. Lone Star Regional was indoors. Car went through Ops on Thursday, judged on Friday. Seize the moment if it appears!