Can We Talk Radiator Caps?

[Fred D.]

1972 Coupe 350/200

Please see my radiator cap in the attached pictures.

RC-15 Top.jpgRC-15 Bottom.jpg

Two questions for those in the know.
1. Can anyone confirm that this is the correct cap?
2. The rubber gasket at the top is missing, and it tends to allow the fluid to leak out (in the form of vapor). Is there a way that I can fix this?

[Patrick H.]

Re: Can We Talk Radiator Caps?

Fred,

1. Appears correct if you have AC.
2. There are people out there who restore radiator caps. I'd suggest that if you want to make it work properly.

Patrick

[John G.]

Re: Can We Talk Radiator Caps?

DeWitt's carries what appears to be an exact repro.

[Gary B.]

Cap restorers

At one time John Pirkle & son were restoring radiator caps. I don't know if they still do, but they did an excellent job, as they do with everything.

Gary

[Kenneth T.]

Re: Can We Talk Radiator Caps?

Fred,

We can talk caps.
1. I concur with Patrick, looks correct to me if you don't have the aluminum expansion tank.

2. The lower gasket is there and that is the one that seals the tank / radiator to enable pressure build up.

If the pressure exceeds the value of the spring (15lbs) it will act as a relief valve, compress and allow the coolant to enter the chamber between the top and bottom gasket. That's the overflow and the hose carries the coolant out.

If you are having too much / frequent expansion and overflow, I would pressure check the cap. I have a Stant unit that can check the radiator / cooling system and the cap. I you know someone who has one, have them test your cap, it may be relieving too early. If the cap checks out, You may have some other problems developing within your cooling system.

That's the reason for the long winded response. You can get repros or NOS R-15s , but it is interesting to know what is going on and why.

Ken

[Fred D.]

Re: Can We Talk Radiator Caps?

Thanks for the info guys.

I do have AC, no expansion tank, and believed it to be correct also (but was never sure).

I switched to this old one in preparation for judging and found that my coolant will slowly go low. It never puddles, so I'm guessing it leaks as vapor (or as liquid while driving and I have never noticed).

I have been using a Stant for many years now with no problems. With my Stant, it has a rubber gasket on the bottom side of the cap, where this one doesn't. I naturally assumed that this one had lost that seal. It sounds like one isn't supposed to be there?

Ken must be right. It must not be holding to 15#. Good idea to test it. I will have to look into some where to do this.

[Mark D.]

Re: Can We Talk Radiator Caps?

I recommend John Pirkle Sr. and Jr. at Masters City. People may tell you they are no longer restoring radiator caps but, that is not correct...they are. They have restored RC-15 and RC-26 caps for me and I have been completely satisfied. See the link below if you care to contact them.

Regards,

Mark

http://www.johnpirkle.com/company%20history/company%20history.htm

[Patrick H.]

Re: Can We Talk Radiator Caps?

DeWitt's carries what appears to be an exact repro.

Please see the Archives as to the accuracy, and inaccuracy, of the variouis repros.

The short answer is that none are exact. Some aren't even that close.

Patrick

[Thad L.]

Re: Can We Talk Radiator Caps?

Pirkle did mine. 70 with a/c looks great. I had the same issue-the gasket was gone. Picked it up in Florida in january.
Thad

[Peter L.]

Re: Can We Talk Radiator Caps?

Fred -

Picture #1 - I keep looking at the picture of the cover and I see the circle around the AC but there does not appear to be a circle around the 15#/RC-15. Is there a circle around the 15#/RC-15 on this cover?

Picture #2 - I suspect that the cap is leaking/not holding pressure is because the rubber seal at the bottom is as hard as a rock, as is the seal under the valve or the seal under the valve might be gone or cracked. These seals can be replaced from a donor AC Radiator Pressure Cap.

Pete

[Fred D.]

Re: Can We Talk Radiator Caps?

Thad, Mark, Gary,

I contacted John Pirkle via email and he replied that he is no longer restoring radiator caps

Wondering out loud if anyone else does this?



Peter,

I was wondering the same thing after studying the judging manual,so I ask someone. I was told the circle over the RC-15 #15 can be really, really faint. Having said that, I still dont see it, so it might not be there.

[Patrick H.]

Re: Can We Talk Radiator Caps?

Thad, Mark, Gary,

I contacted John Pirkle via email and he replied that he is no longer restoring radiator caps

Wondering out loud if anyone else does this?



Peter,

I was wondering the same thing after studying the judging manual,so I ask someone. I was told the circle over the RC-15 #15 can be really, really faint. Having said that, I still dont see it, so it might not be there.

I'll try to remember to bring my scope to the meet, and we can look.

Patrick

[Henry S.]

Re: Can We Talk Radiator Caps?

Patrick,
I just re-read the Winter 2006 Restorer article. That was a good article. There was mention of possible another article in the works, do you know the status of it? I am looking for the best repros of the RC26, since you have studied these which do you think is closest to original, if any? Thanks for your advice. Shooter

[Jeffrey S.]

Re: Can We Talk Radiator Caps?

Pete:
You said that the seals can be replaced using ones from a donor cap. Does the cap needing the repair have to be disassembled/rivet drilled out to exchange the seals?
Jeff

[Patrick H.]

Re: Can We Talk Radiator Caps?

Patrick,
I just re-read the Winter 2006 Restorer article. That was a good article. There was mention of possible another article in the works, do you know the status of it? I am looking for the best repros of the RC26, since you have studied these which do you think is closest to original, if any? Thanks for your advice. Shooter

Article?
Hmm. Kinda stalled due to a variety of issues, but all the info is still on my computer. The RC-26 is actually a bit harder to track.

"Generally" LICS has some very nice repros, definitely the best of the RC-26. His RC-15 would be better if he accepted that what ACDelco built doesn't match the drawing in one small area. Until that happens his repros remain detectable.

Patrick