pressure on the cooling system? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Blue_71 · 07-31-2003, 09:20 PM

when my truck gets up to about 220 degrees it starts blowing hoses off.... ive finally took a wrench and tightened every clamp to almost breaking and it hasnt done it sinse... ive got a 2 core radiator, long chrome water pump, no heater so the hose is just looped from pump to intake, no thermostat, and a 15 lb cap... it'll blow a 8 lb off quick.... last time it did it to me i had 2 girls in the truck and nothing blocking the heater hole and the truck was about 220

(you can bet your butt i made a cover for the hole as soon as i got home)

Gordo · 07-31-2003, 09:26 PM

If you don't have a fan shroud, it may be your problem. It's also a good idea to run a stat, sometimes the coolant flows threw the radiator to quickly and doesn't cool down enough.

Two girls in the truck, you dog you!

Longhorn Man · 07-31-2003, 09:27 PM

Why don't you have a thermostat?

lukecp · 07-31-2003, 09:38 PM

Throw a 180 degree stat in there....that could be a big part of the problem since the stat controls the flow of coolant. It shouldn't be running at 220 without a stat. I would imaigne it would run much cooler than that w/o a stat.

Blue_71 · 07-31-2003, 10:00 PM

no stat cause the old one was froze up and i didnt have the $$ to get a new one

forgot to mention ive got a flex fan and a 2wd fan shroud. it usually doesnt get past 200, but it was about 100 that day out and of course you know i was being a show off

i was wondering if it could have anything to do with the stat and not having a heater core

Alex · 07-31-2003, 10:00 PM

It would run hot without the thermostat because the coolant doesn't have the chance to absorb the heat of the block before it runs back to the radiator. The thermostat slows the coolant flow. So, get one in there before you tackle any other issues with the cooling system.

Longhorn Man · 08-01-2003, 08:54 AM

Alex hit the nail right on the head.
And whats with the flex fan Josh? I thought you knew better than that. I have one of those foam air filters you can have too if you want it.

**old Rusty C10** · 08-01-2003, 10:12 AM

get the flex fan off of there dammit!!!!! and the stat should be in there
gee whiz kids!!!!!!!!!!!!
lol id also look for the right shroud although it wont make too much of a difference

ChevLoRay · 08-01-2003, 11:03 AM

My son's hot rod '69 had a flex fan, and it didn't overheat. You need a fan shroud, regardless of which fan you run. You also need the thermostat, for the reasons that everyone else has mentioned. They don't cost any more than a couple of gallons of gas, but I understand your delimna. When you have girls to haul around, you need gas, not a thermostat. Gasoline, though, not "gas".

Regardless of which thermostat you use, you may need more radiator than a 2-row core can do for your engine cooling. The heater may help your cooling, when it overheats, but if the weather is HOT and you have girls in the cab, more heat is the lat thing you need.....well, maybe. Let's see....I can always put on more clothes and get warm when I get cold, but I can't take off enough clothes to get cool, when I get hot.....Nah. Don't want to go there.

Your fan blades, fixed or flex, should be about two inches from the radiator, with a shroud, to pull the largest volume of air through the radiator, with the thermostat to restrict the flow of coolant, allowing it enough time to stay in the radiator and cool down.

Blue_71 · 08-02-2003, 03:17 AM

the flex fan was free and it looks perty

lol with the 2wd shroud the fan sits even with theoutside rim of the shroud... this is with a LWP, spacer, and flex fan

here's the evil colperate

**Stocker** · 08-02-2003, 09:44 AM

FWIW... My mild 350 doesn't overheat with the stock 2-core radiator, even w/temps over 100*. And the stock clutch fan sits several inches away from the radiator (but flush with the shroud). However...

Several years ago the fan clutch went bad, so I put on a flex fan which was a perfect fit. Only thing is, the truck would overheat! So I fixed the clutch (new silicon fluid) and it's been good ever since.

Obviously, my opinion is ditch the flex fan and get a clutch fan. You should be able to get a junkyard unit cheap. Just take measurements, look for a relatively new one on a larger car or truck. And oh yeah - throw a thermostat in there!

Longhorn Man · 08-03-2003, 11:26 PM

I never heard of flex fans overheating till now...but I have seen plenty of proof about them blowing up and cutting through the hood.

*racedvl* · 08-03-2003, 11:55 PM

Get rid of the flex fan, any chrome that has to do with your cooling system, and for the love of God, drop a t-stat in that pig!

CHROME DOES NOT COOL!!!! It is one of the worst things as far as dissapating heat goes.

07-31-2003, 09:26 PM	#2
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	If you don't have a fan shroud, it may be your problem. It's also a good idea to run a stat, sometimes the coolant flows threw the radiator to quickly and doesn't cool down enough. Two girls in the truck, you dog you! __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

07-31-2003, 09:38 PM	#4
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Throw a 180 degree stat in there....that could be a big part of the problem since the stat controls the flow of coolant. It shouldn't be running at 220 without a stat. I would imaigne it would run much cooler than that w/o a stat. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

07-31-2003, 10:00 PM	#6
Alex Registered User Join Date: Jan 2000 Location: Blaine, MN Posts: 798	It would run hot without the thermostat because the coolant doesn't have the chance to absorb the heat of the block before it runs back to the radiator. The thermostat slows the coolant flow. So, get one in there before you tackle any other issues with the cooling system. __________________ '72 C/10 LWB 402/400 Blaine, MN

08-01-2003, 10:12 AM	#8
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,313	get the flex fan off of there dammit!!!!! and the stat should be in there gee whiz kids!!!!!!!!!!!! lol id also look for the right shroud although it wont make too much of a difference __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

08-01-2003, 11:03 AM	#9
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Flex fans aren't bad... My son's hot rod '69 had a flex fan, and it didn't overheat. You need a fan shroud, regardless of which fan you run. You also need the thermostat, for the reasons that everyone else has mentioned. They don't cost any more than a couple of gallons of gas, but I understand your delimna. When you have girls to haul around, you need gas, not a thermostat. Gasoline, though, not "gas". Regardless of which thermostat you use, you may need more radiator than a 2-row core can do for your engine cooling. The heater may help your cooling, when it overheats, but if the weather is HOT and you have girls in the cab, more heat is the lat thing you need.....well, maybe. Let's see....I can always put on more clothes and get warm when I get cold, but I can't take off enough clothes to get cool, when I get hot.....Nah. Don't want to go there. Your fan blades, fixed or flex, should be about two inches from the radiator, with a shroud, to pull the largest volume of air through the radiator, with the thermostat to restrict the flow of coolant, allowing it enough time to stay in the radiator and cool down. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

07-31-2003, 09:27 PM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Why don't you have a thermostat?

08-01-2003, 08:54 AM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Alex hit the nail right on the head. And whats with the flex fan Josh? I thought you knew better than that. I have one of those foam air filters you can have too if you want it.

08-02-2003, 09:44 AM	#11
Stocker 20' Daredevil (Ret) Join Date: May 2003 Location: Jefferson State Posts: 13,728	Nice lookin' engine... FWIW... My mild 350 doesn't overheat with the stock 2-core radiator, even w/temps over 100. And the stock clutch fan sits several* inches away from the radiator (but flush with the shroud). However... Several years ago the fan clutch went bad, so I put on a flex fan which was a perfect fit. Only thing is, the truck would overheat! So I fixed the clutch (new silicon fluid) and it's been good ever since. Obviously, my opinion is ditch the flex fan and get a clutch fan. You should be able to get a junkyard unit cheap. Just take measurements, look for a relatively new one on a larger car or truck. And oh yeah - throw a thermostat in there! __________________ - Mike - 1972 K20 LWB 350/350/205 RIP El Jay

08-03-2003, 11:26 PM	#12
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	I never heard of flex fans overheating till now...but I have seen plenty of proof about them blowing up and cutting through the hood.

08-03-2003, 11:55 PM	#13
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	Get rid of the flex fan, any chrome that has to do with your cooling system, and for the love of God, drop a t-stat in that pig! CHROME DOES NOT COOL!!!! It is one of the worst things as far as dissapating heat goes.



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