| |
Labor Day Putting down your wrenches or time for
MORE wrenching? 
Plenty of places to share. | | Click on image for the lowdown. 
====
| | |
7 members (Wickedbass, Wally / Montana, TexasA&M48Truck, FAST55, Chester2392, JW51, 68ironhead),
50
guests, and
4
robots. | | Key: Admin,
Global Mod,
Mod | | | Forums66 Topics128,010 Posts1,055,298 Members48,419 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | 
#47753 07/16/2005 12:44 PM | Joined: Oct 2004 Posts: 7 Junior Member | | Junior Member Joined: Oct 2004 Posts: 7 | I have a 48 3/4 ton with a 1960 235 in it.Its been on the road for 2 years now and all of a sudden in the past week everytime i drive it at highway speeds it pours antifreeze out the overflow tube when i shut it off.It has a waterpump from Carter and a new 160 T-stat.It never overheats and only started this problem in the 90 degree days we are having now.Any suggestions?
Joe Bruno
| | |
#47755 07/16/2005 1:40 PM | Joined: Mar 2005 Posts: 85 Wrench Fetcher | | Wrench Fetcher Joined: Mar 2005 Posts: 85 | Is there a spring in your radiator hose(s). Could one be collapsing at highway speed? It is possible... | | |
#47756 07/16/2005 2:30 PM | Joined: Feb 2004 Posts: 29,742 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,742 | Have somebody test the radiator cap. A weak pressure relief spring, and/or a bad gasket will allow it to puke coolant after shutdown. A good-condition cap a couple of pounds higher rating might help IF you've got a tubular radiator that will handle the extra pressure. Don't overstress a honeycomb radiator with a too-high pressure cap.
A recovery system will allow it to recycle the coolant, if you don't mind going non-stock.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | |
#47757 07/16/2005 7:22 PM | Joined: Mar 2005 Posts: 1,029 Member | | Member Joined: Mar 2005 Posts: 1,029 | The next time it happens, don't top it up and see if it happens the time after. You may just be overfilling. Another thing to do is to not shut down immediatly after high speed driving; cool-off laps so to speak.
Timing is also more critical in hot weather, you may need to advance the timing slightly.
Baldy | | |
#47758 07/16/2005 10:06 PM | Joined: Feb 2001 Posts: 81 Shop Shark | | Shop Shark Joined: Feb 2001 Posts: 81 | I have a 62 chevy 1/2 ton truck with a 235 six that once had the same problem. Suggested solution-go to Auto-Zone or similar store and purchase an overflow kit-shouldn't cost over $10 -and install on your truck. Also use a 7 pound pressure cap. Expect overflow after most drives but the antifreeze siphens back in your radiator instead of on the ground! This setup has worked for me for over 20 years in this Texas climate of over 100 degrees so should work for you. I am assuming that your radiator is in good shape? Hope this helps.
Green Machine
| | |
#47759 07/16/2005 10:34 PM | Joined: Jan 2000 Posts: 2,074 'Bolter | | 'Bolter Joined: Jan 2000 Posts: 2,074 | Also, use only amount of coolant to contol corrosion. Straight coolant only increases the boiling point, a mixture with more water actually cools better. Went on a run with several old cars some years back, one car puked coolant right out the gate. After several stops and adding water we finally got the mixture right, never boiled over again.
Overflow catch can is also the way to go. | | |
#47760 07/17/2005 11:30 AM | Joined: Oct 2004 Posts: 7 Junior Member | | Junior Member Joined: Oct 2004 Posts: 7 | Thanks so much.I do have an overflow tank but have a stock O lb. pressure cap.I will try a 4 lb. and see if that does it.Thanks again 
Joe Bruno
| | |
#47761 07/17/2005 2:10 PM | Joined: Sep 2003 Posts: 343 Member | | Member Joined: Sep 2003 Posts: 343 | What pressure rating cap should we use on a stock (1954) radiator? I am assuming these are the low pressure type radiators.
1954 GMC 1/2-ton Longbed
1971 Pontiac LeMans Sport
| | |
#47762 07/17/2005 2:29 PM | Joined: Feb 2005 Posts: 399 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Feb 2005 Posts: 399 | shop manual says 4#..that's what I have in mine | | |
#47763 07/19/2005 12:58 AM | Joined: Mar 2005 Posts: 170 Member | | Member Joined: Mar 2005 Posts: 170 | Does your radiator neck have provision for a pressure cap ? I believe the overflow tube needs to come off the neck at the cap so coolant will only come out when the cap lifts.
I'm putting a new 235 into my '40 and have been thinking about the same issue. My radiator has a 0 pound cap and the overflow tube comes off the top of the radiator, not the filler neck. I expect to have to have the neck changed to take a pressure cap and move the overflow tube to the neck.
Steve | | |
|
|
| |
