Coolant/Thermostat Problem??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**COBALT** · 06-01-2002, 03:46 PM

Ok, so I got all the new hoses on + a new thermostat, and started filling the system with coolant/water.

1. I thought these things took 15 or 16 quarts of coolant/water? I can only get 8 in. What's the scoop? The only way I know to get coolant in the system is to pull the cap on the flushing tee, and fill the radiator until crap comes out the tee, then run the truck while filling until you have fluid coming out of the tee AND the radiator is full...

2. The truck starts heating up damn quick. It goes past the 1st mark (where it normally sits all the time) and slowly creeps to the 1/2 way mark. This thing is heating up too fast I think. Isn't the thermostat supposed to open??? Is the thermostat not doing its job (it's in the right way), or is it simply that I don't have enough coolant in?

WTF?

Longhorn Man · 06-01-2002, 04:50 PM

8 quarts sounds about right to me. Never actually checked it, but it sounds close enough.
As for heating up, does it get 1/2 way up and stay there? If so, iI'd say your thermo stat is doing it's jub right.
It is not only supposed to keep it from overheating, but is supposed to retaIn the coolant untill it is up to temp. Otherwise, you would be able to remove your stat and forget about it.

**COBALT** · 06-01-2002, 04:51 PM

Ok, I let the truck run on idle for a while. The temperature passes the first mark, but settles about 1/16" past it, then stops. I think this is the new operating temp after replacing the thermostat.

I'm still confused about the capacity. I could have sworn that these trucks took 15 or 16 quarts instead of 8 (4 gallons instead of 2 gallons). Am I just on drugs or what?

Longhorn Man · 06-01-2002, 05:00 PM

Yeah...I think so.

LOL

71Chev · 06-01-2002, 05:10 PM

Coolant capacity is right at about 2 gals.
What temp thermostat did you put in?
185 degree should run about straight up on a factory temp gauge.
160 degree will run a little left of center.

Stop the flashing avatar, PLEASE.

**COBALT** · 06-01-2002, 05:30 PM

sorry. A little revenge for the flashing add...supposed to be funny.

OK, I have a 160 degree thermostat. It looks as though it's holding operating temp just fine, so I guess I'm being paranoid. It's just that the old thermostat kept the operating temp at the first mark ALWAYS, and since I haven't had any other experiences with these trucks well...

8 Quarts should be right on the money, huh? Wow. I must be smoking coolant, and my Hanes manual is full of sh!t. LOL

thanks guys.

71Chev · 06-01-2002, 06:04 PM

Thanks for the new avatar.

Is it possible that the old thermostat was a Fail Safe type thermostat that had failed? When those fail they lock in the open position allowing coolant to flow constantly. Maybe this is why you were running cooler before. Just an idea.

**COBALT** · 06-01-2002, 11:22 PM

Yeah, that had occurred to me. No idea, but I guess that's just as good of an explanation as any...oh well works now!

06-01-2002, 03:46 PM	#1
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Coolant/Thermostat Problem??? Ok, so I got all the new hoses on + a new thermostat, and started filling the system with coolant/water. 1. I thought these things took 15 or 16 quarts of coolant/water? I can only get 8 in. What's the scoop? The only way I know to get coolant in the system is to pull the cap on the flushing tee, and fill the radiator until crap comes out the tee, then run the truck while filling until you have fluid coming out of the tee AND the radiator is full... 2. The truck starts heating up damn quick. It goes past the 1st mark (where it normally sits all the time) and slowly creeps to the 1/2 way mark. This thing is heating up too fast I think. Isn't the thermostat supposed to open??? Is the thermostat not doing its job (it's in the right way), or is it simply that I don't have enough coolant in? WTF? __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

06-01-2002, 04:51 PM	#3
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Ok, I let the truck run on idle for a while. The temperature passes the first mark, but settles about 1/16" past it, then stops. I think this is the new operating temp after replacing the thermostat. I'm still confused about the capacity. I could have sworn that these trucks took 15 or 16 quarts instead of 8 (4 gallons instead of 2 gallons). Am I just on drugs or what? __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

06-01-2002, 05:10 PM	#5
71Chev Senior Member Join Date: Dec 2000 Location: Indiana Posts: 3,074	Coolant capacity is right at about 2 gals. What temp thermostat did you put in? 185 degree should run about straight up on a factory temp gauge. 160 degree will run a little left of center. Stop the flashing avatar, PLEASE. __________________ 71 Chevy CST Long Fleet 350/350/3.07 leaf rear.

06-01-2002, 05:30 PM	#6
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	sorry. A little revenge for the flashing add...supposed to be funny. OK, I have a 160 degree thermostat. It looks as though it's holding operating temp just fine, so I guess I'm being paranoid. It's just that the old thermostat kept the operating temp at the first mark ALWAYS, and since I haven't had any other experiences with these trucks well... 8 Quarts should be right on the money, huh? Wow. I must be smoking coolant, and my Hanes manual is full of sh!t. LOL thanks guys. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

06-01-2002, 06:04 PM	#7
71Chev Senior Member Join Date: Dec 2000 Location: Indiana Posts: 3,074	Thanks for the new avatar. Is it possible that the old thermostat was a Fail Safe type thermostat that had failed? When those fail they lock in the open position allowing coolant to flow constantly. Maybe this is why you were running cooler before. Just an idea. __________________ 71 Chevy CST Long Fleet 350/350/3.07 leaf rear.

06-01-2002, 04:50 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	8 quarts sounds about right to me. Never actually checked it, but it sounds close enough. As for heating up, does it get 1/2 way up and stay there? If so, iI'd say your thermo stat is doing it's jub right. It is not only supposed to keep it from overheating, but is supposed to retaIn the coolant untill it is up to temp. Otherwise, you would be able to remove your stat and forget about it.

06-01-2002, 05:00 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Yeah...I think so. LOL

06-01-2002, 11:22 PM	#8
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Yeah, that had occurred to me. No idea, but I guess that's just as good of an explanation as any...oh well works now! __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

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