Radiator caps...what rating to use?

Edbert

Founding Member

Jul 13, 2002

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Austin TX

Feb 27, 2008

#1

• Feb 27, 2008

• #1

Standard caps are either 14 or 16 pound caps right? I was looking around and see high-performance caps rated at 20# and even some as high as 28#!

So, the difference determines how much pressure can build before it releases, thus allowing higher temperatures? What is the benefit or detriment of getting a higher rating?

 

iskwezm

10 Year Member

May 24, 2005

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Rowland Heights,California

Feb 27, 2008

#2

• Feb 27, 2008

• #2

A higher pressure cap will raise the boiling point of the water, but too high will stress your cooling system if its not up to the increased pressure.

 

69gmachine

Member

Dec 2, 2004

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Southern Maryland

Feb 27, 2008

#3

• Feb 27, 2008

• #3

Stick with the 14# cap. You'll probably just create a leak somewhere because the cap won't vent.

 

B

bnickel

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Aug 21, 2002

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lubbock, texas

Feb 27, 2008

#4

• Feb 27, 2008

• #4

stock mustang caps can go as low as 9lb depending on the application but most use a 13lb one. i wouldn't personally go any higher than 16lb.

 

66 Restomod

Member

Jan 2, 2007

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Raleigh, NC

Feb 28, 2008

#5

• Feb 28, 2008

• #5

Just wondering, is there a difference on cap pressure if a non-stock overflow tank or catch can is added? I'm thinking of adding a catch can next to the radiator on my 66, not sure if I'll need a new cap...

 

Tim65GT

Active Member

Feb 24, 2004

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West Texas

Feb 28, 2008

#6

• Feb 28, 2008

• #6

Just wondering, is there a difference on cap pressure if a non-stock overflow tank or catch can is added? I'm thinking of adding a catch can next to the radiator on my 66, not sure if I'll need a new cap...

Click to expand...

No, they have two independant purposes. Just route a hose from the overflow tube at the neck to the new catch can that will allow the coolant to siphon back into the radiator as it cools.

 

Edbert

Founding Member

Jul 13, 2002

3,548

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Austin TX

Feb 28, 2008

#7

• Feb 28, 2008

• #7

Yeah, the neck has the outlet not the cap. The pressure rating on the cap determines at what point fluid is released into the top of the neck.

 

B

bnickel

Founding Member

Aug 21, 2002

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lubbock, texas

Feb 28, 2008

#8

• Feb 28, 2008

• #8

the caps are different though. the one with a catch can will have 2 rubber seals one without will only have one seal. these days you'd be hard pressed to find a cap that doesn't have 2 seals though.