RE: [Chrysler300] Radiator cap pressure 300C

["'John L. Chesnutt' chesnutt@xxxxxxxxxxxx [Chrysler300]" <Chrysler300-noreply@xxxxxxxxxxxxxxx>]

Hi,
I have always used a 14# cap and have had no problem for the last 59 years we have had our 1957 300C. Several years ago I finally put a new core in the radiator as the tubes looked like they were leaking. The replacement was a four tube vs the original three tube. The shop that I use said he could not get a three tube from his suppler. A 7# cap is ok, but I would rather not lose any water when driving at high speed on hot days. The four tube took about a half gallon more water than the original.

John

-----Original Message-----
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of 'Henry Schleimer' henry.schleimer@xxxxxxxxxxxxxxx [Chrysler300]
Sent: Tuesday, October 17, 2017 7:06 PM
To: 'Larry Jett'; 'John Grady'
Cc: 'chrysler300@xxxxxxxxxxxxxxx'
Subject: RE: [Chrysler300] Radiator cap pressure 300C

241 degrees is about 6 psi with the 50% coolant mix that I use.  The radiator guy also said there are 10 and 13 psi caps available.

 

Cheers  Henry

 

From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Larry Jett LarryWJett@xxxxxxxxx [Chrysler300]
Sent: Wednesday, 18 October 2017 11:15 AM
To: John Grady
Cc: Henry Schleimer; chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] Radiator cap pressure 300C

 

  

Can't speak to the 57 radiators, but on the way to the New Mexico meet, our 63 300 sport indicated 241 degrees on my Dakota Digital heat gage and nothing blew on the way up the Grapevine in 105 ambient.  Using the 14 pound cap.  




Eat, Drink, and be Larry........

 

 

 

 

 

 

 

                                                                     

 

 

 

On Tue, Oct 17, 2017 at 5:41 PM, John Grady jkg@xxxxxxxxxxxxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

  

I agree with that 100% . Smart guy 

Sent from my iPhone


On Oct 17, 2017, at 7:47 PM, 'Henry Schleimer' henry.schleimer@optusnet.comau [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:

Poked a small hole in my radiator and took it a radiator shop yesterday to get soldered.  While there I asked for a new 14 lb radiator cap.  The owner said I didn’t want one that high and recommended a 7lb cap.  After I said that 14 was the factory spec he said he was aware of that BUT for the old style large tank radiators the pressure is too high making them crack along the top seam.  The difference in temp is not that great but the stress in the solder is much reduced.  He said if you get over 100 C your have problems with your system anyway.

 

I then remembered my parents’ 67 Valiant which had the same top tank design and recalled we must have had the top tank resoldered about 4 times in its life.  I said I had never heard a radiator guy recommend a lower cap pressure.  He said it was funny that!  He also said if I fitted a 7 lb cap he wouldn’t see me for the next 20 years!

 

To reinforce the issue of the big top tank having a flex problem, he pointed out the bottom smaller tank usually never cracks.  It all started to make sense.

 

I know this may generate many opinions but I’m willing to give it a try.  I thought I might pass this on to people who have the same problem with tanks cracking in an otherwise ok cooling system.

 

If I don’t have any cooling problems at the lower pressure, there is no need  to put extra stress on the system.  Better the cap lets go rather than the radiator, hose, block plug etc.  If it keeps losing too much water, I can always go up in pressure.

 

Cheers

 

Henry

 

 

 





[Non-text portions of this message have been removed]



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Posted by: "Henry Schleimer" <henry.schleimer@xxxxxxxxxxxxxxx>
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Posted by: "John L. Chesnutt" <chesnutt@xxxxxxxxxxxx>
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