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#69318 11/28/2006 5:39 PM | Joined: Nov 2005 Posts: 30 Apprentice | | Apprentice Joined: Nov 2005 Posts: 30 | Hi Folks, Just a quick question as I put my '52 GMC back together. The radiator I have is not pressurized, which seems to me like a bad idea. should I modify it to hold pressure and run a 6 lb cap, or leave well enough alone? I am running a stock 270, and live in 100+ degree summers. I have an old Brit car that won't make it to the end of the driveway without a 13lb cap and a big electric fan... Maybe the unpressurized system works fine the way it is? Thanks, Tom | | |
#69319 11/28/2006 6:13 PM | Joined: Feb 2002 Posts: 12,029 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Feb 2002 Posts: 12,029 | most came with a 3lb I think, and 7lb is about as much as ya wanna stress the ol rad
Bill | | |
#69320 11/28/2006 6:46 PM | Joined: Dec 2003 Posts: 2,733 Shop Shark | | Shop Shark Joined: Dec 2003 Posts: 2,733 | I would advise the use of a proper pressurized cap or you invite boiling problems. | | |
#69321 11/28/2006 6:49 PM | Joined: Aug 2005 Posts: 6,377 Ex Hall Monitor | | Ex Hall Monitor Joined: Aug 2005 Posts: 6,377 | You should be OK unpressurized if you don't sit idling for periods of time. It gets over 100 here too & the 38 is unpressurized. The only time it gets uncomfortably warm is at idle. For that fact that's when I get uncomfortably warm too. 
Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.
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#69322 11/28/2006 6:55 PM | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Tom,
Do you have a shop manual for your engine and/or truck? The GMC radiator and engines are distinctly different from those used in same year Chevrolet trucks.
I think that a 1952 Chevrolet small-truck radiator cap was 0 lbs pressure. In 1954 that changed to 4 lbs pressure in small trucks and 7lbs pressure in automobiles.
If you have a GMC radiator, I think there is a pressure-relief valve on the radiator. Maybe a GMC person can provide information about using a pressure cap on these radiators (maybe someone above was specifically referring to a GMC radiator/engine?).
Tim | | |
#69323 11/29/2006 1:56 AM | Joined: Mar 2004 Posts: 3,068 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 3,068 | I would use a low pressure cap and an overflow catch can, to keep the radiator full.
Just my 2 cents,
Scott | | |
#69324 11/29/2006 2:43 PM | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | I have the GMC radiator, just like the one in the manual. It has the 4 lb relief valve over to the side. The main filler does not have a spill pipe/hole in the neck so no matter what cap you put on, there will be no regulated relief through the main cap. The pressure relief comes from the spring loaded seal at the bottom of the cap assembly and when that opens, there is supposed to be an exit hole above that and below the top of the cap. This hole is missing in the GMC type setup, at least in the manual and on my radiator. | | |
#69325 11/30/2006 6:50 AM | Joined: Sep 2006 Posts: 12 Apprentice | | Apprentice Joined: Sep 2006 Posts: 12 | my 52 gmc has been running a 6 lb cap for years and even on the hottest day in the summer the engine temp never gets above 180  | | |
#69326 11/30/2006 1:34 PM | Joined: Mar 2006 Posts: 483 Shop Shark | | Shop Shark Joined: Mar 2006 Posts: 483 | | | |
#69327 11/30/2006 3:24 PM | Joined: Aug 2005 Posts: 6,377 Ex Hall Monitor | | Ex Hall Monitor Joined: Aug 2005 Posts: 6,377 |
Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.
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