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#1209441 - Mon Mar 20 2017 02:38 AM Re: radiator cap [Re: DaveV]  
Achipmunk  Offline
Joined: Dec 2001
Posts: 15,762
Boiling Springs, S. C. 29316
Can you find another radiator shop close by??? We have an older shop here that will actually order the pieces it takes to "make up" a heater core but I'll admit, its a bit pricey at around 200 bucks but then most of us would never have to worry about it in our live time....or at least it could be repaired later.
Don't give up just yet...........

1937 Chevy Pickup
1952 Chevy Panel
Pictures in my Photobucket
1950 Chevy Coupe

I'd rather walk and carry a Chevy hub cap than ride in a Ferd.
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#1209457 - Mon Mar 20 2017 04:45 AM Re: radiator cap [Re: DaveV]  
Forty9  Offline
Shop Shark
Joined: Apr 2008
Posts: 637
Henderson, Nevada
Stant 10203 is a 0 pressure cap. Napa can cross reference it to their brand. Amazon also has Stant 10203.


#1209468 - Mon Mar 20 2017 11:40 AM Re: radiator cap [Re: Forty9]  
DaveV  Offline
Shop Shark
Joined: Sep 2012
Posts: 86
SE Wis
So it is ok to run a 0 psi cap. Thanks for all the replies. Dave

Last edited by DaveV; Mon Mar 20 2017 11:43 AM.

#1209485 - Mon Mar 20 2017 02:15 PM Re: radiator cap [Re: DaveV]  
tclederman  Online
Joined: Sep 2001
Posts: 25,908
Jarvisburg, NC
Yes, a 0 psi radiator cap is OK.

4psi should also be OK.

If you go higher, you might be moving into pressure-territory that might be too high for other components (the heater, for example).

1954 3106 Carryall Suburban - part of the family for 46 years
1954 3104 5-window pickup w/Hydra-Matic
Z-series (54/55) GMC 350 (2-ton) COE
If you have to stomp on your foot-pedal starter, either you, or your starter, or your engine, has a problem.

#1209573 - Tue Mar 21 2017 12:52 AM Re: radiator cap [Re: Hotrod Lincoln]  
52Carl  Offline
Master Gabster
Joined: Mar 2010
Posts: 5,167
Originally Posted By Hotrod Lincoln
. You can make a zero-pressure cap by removing the lower rubber gasket of the existing cap.

Hey Jerry,
For an overflow tank to function, doesn't the radiator cap need to have a tight seal as the antifreeze cools off? The coolant loses volume as it cools, creating a vacuum which is the force that draws the coolant back out of the overflow tank. If the cap has had the seal removed, wouldn't that break the vacuum, preventing the coolant to be drawn back into the radiator? Maybe I don't understand how a pressure cap, modified by removing the lower seal works.

#1209661 - Tue Mar 21 2017 03:43 PM Re: radiator cap [Re: DaveV]  
Jim Sears  Offline
Shop Shark
Joined: Jan 2013
Posts: 1,475
As long as the neck of the radiator is sealed then all the pressure/vacuum is acting on the overflow tube. A pressure cap with the lower seal removed still seals the top of the neck.
You should always start with the radiator full to the top and the tank 1/2 full. It will eventually equalize to a level doesn't overflow and is air free.

Last edited by Jim Sears; Tue Mar 21 2017 03:45 PM.

#1209673 - Tue Mar 21 2017 05:08 PM Re: radiator cap [Re: DaveV]  
Hotrod Lincoln  Offline
Joined: Feb 2004
Posts: 15,314
Dellrose, TN
Jim's got the picture. There is a flexible metal piece at the top of the cap that seals the top of the filler neck as the cap is tightened fully. It would also be possible to drill the top of the radiator cap for a long sheet metal screw that would retract the spring loaded center of the cap slightly to prevent pressure buildup. A factory 0-PSI cap is a better choice, though.

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#1209743 - Wed Mar 22 2017 01:42 AM Re: radiator cap [Re: DaveV]  
52Carl  Offline
Master Gabster
Joined: Mar 2010
Posts: 5,167
Thank you for the education gents. (Glad I didn't go all "I-told-you-so, what-were-you-thinking-with-your-2-3-braincells-to-rub-together, etc. smile )

#1209798 - Wed Mar 22 2017 05:04 AM Re: radiator cap [Re: DaveV]  
Rich'sToys  Offline
Shop Shark
Joined: Jul 2004
Posts: 3,085
Janesville, Mn
I learned something there too!


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