The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 09-28-2010, 03:16 PM   #1
67sss
Registered User
 
67sss's Avatar
 
Join Date: Nov 2002
Location: Mt. Vernon, WA..
Posts: 2,322
coolant overflow

I have a 68 project truck with a 350, and yesterday after running it in the driveway for a while, I turned it off then coolant came out of the overflow tube on the radiator. Temp gauge read normal, new thermostat installed and mixed 50/50 coolant. Why would this happen? What size radiator cap should I use?

Thanks.
67sss is offline   Reply With Quote
Old 09-28-2010, 03:23 PM   #2
Lance-ftw
Registered User
 
Lance-ftw's Avatar
 
Join Date: Sep 2010
Location: Fort Worth, Texas
Posts: 143
Re: coolant overflow

Quote:
Originally Posted by 67sss View Post
I have a 68 project truck with a 350, and yesterday after running it in the driveway for a while, I turned it off then coolant came out of the overflow tube on the radiator. Temp gauge read normal, new thermostat installed and mixed 50/50 coolant. Why would this happen? What size radiator cap should I use?

Thanks.
my first guess would be radiator cap is too weak. I think 13lbs is standard isnt it? Some one would have to confirm that.
Lance-ftw is offline   Reply With Quote
Old 09-28-2010, 03:54 PM   #3
El Jay
Gone to greener pastures
 
Join Date: May 2007
Location: Gateway to the Delta
Posts: 7,354
Re: coolant overflow

If you don't have a catch tank that is normal.
If you look at a stock radiator, you'll see that "FULL COLD" (or something like that) is embossed on the radiator tank about 2"-3" below the filler neck.

Both of my trucks had 16# caps on them when I got the trucks, so that is what I continue to run.
__________________
'69 Chevy 1/2 T LWB Stepper: Daily Beater
'72 GMC 3/4 T Fleet: Another Daily Beater
'72 Plymouth Gran Coupe: ?


"Ah women. They make the highs higher and the lows more frequent." Friedrich Nietzsche

"Never kick a fresh turd on a hot day." Harry S. Truman

GUN CONTROL: Never having to say, "I missed you."

Always fire two warning shots into your attacker's chest area before putting a bullet between his eyes. Paraphrased from Louis Awerbuck
El Jay is offline   Reply With Quote
Old 09-28-2010, 04:14 PM   #4
Stocker
20' Daredevil (Ret)
 
Stocker's Avatar
 
Join Date: May 2003
Location: Jefferson State
Posts: 13,591
Re: coolant overflow

^^ Yep... iirc, A/C rigs use 16# and non-A/C use about 13#. If you fit a coolant recovery tank (advisable) be sure to get a cap for a sealed system or the coolant won't get sucked back into the radiator as it cools.
__________________
- Mike -

1972 K20 LWB 350/350/205

RIP El Jay
Stocker is offline   Reply With Quote
Old 09-28-2010, 05:04 PM   #5
'72customdeluxe
Registered User
 
Join Date: Jan 2008
Location: Tejas
Posts: 691
Re: coolant overflow

Might have just burped a little excess fluid
__________________
'72 cheyenne super step, '05 long bed gmc
'72customdeluxe is offline   Reply With Quote
Old 09-28-2010, 07:59 PM   #6
68gmsee
Active Member
 
68gmsee's Avatar
 
Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
Re: coolant overflow

Everytime I filled the radiator on my 69 it would burp out fluid out until it was happy. Usually about 2 inches below full. Never had a problem with overheating.

My 68 GMC did the same but would run hotter than normal on unusually hot days. I installed an overflow tube made from black pvc pipe and replaced the cap as mentioned above. Never overheated this last summer and everytime I check the fluid the radiator is full. I guess it just likes a full radiator.
68gmsee is offline   Reply With Quote
Old 09-28-2010, 08:23 PM   #7
frankdatank01
Registered User
 
Join Date: Jun 2007
Location: Dayton, Ohio
Posts: 95
Re: coolant overflow

Can't help with the diagnosis, but I had a Ford Pinto in high school that did this every time I stopped the car in the parking lot (it had no overflow catch can, just a tube pointed at the ground. After a while it was a big event as I would be about 25 feet away, put my arm up to the sky and then bring it down on queue. It was awesome and I received great cheers....

Tank
frankdatank01 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 05:15 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com