Water pump/radiator question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bpmcgee · 10-17-2003, 12:41 PM

Hi,

I've got a 71 blazer, manual transmission, no A/C. The PO bastardized pretty much everything in the truck, including (I think) the radiator.

Right now the heater core has hose going from the intake, and another from the top of the radiator. The port on the side of the waterpump has been plugged.

Here's my question -- How was this originally plumbed? The waterpump that NAPA lists for this truck has no port on the side of it for the heater core. Also, they show a 71 radiator that doesn't have a port for the heater core either! What's up with this?

Thanks,

Brian

JimKshortstep4x4 · 10-17-2003, 01:51 PM

This is what my radiator man told me. Trucks with ac should have the outlet on the radiator for the heater. This does not always hold true, but I have seen it setup this way on some original installations. With these trucks over thirty years old, a lot of changes have been done to them over the years.

It is not a bad thing to run the heater to the radiator as far as I can tell.

Jim

jef5150 · 10-17-2003, 01:55 PM

ok,this is the way your radiator/heater core is "SUPPOSED" to be hooked up, your gonna get replys that say it doesnt matter how you hook it up ,im just saying this is how its "supposed" to be done according to chevrolet,,jeff

67cst · 10-17-2003, 02:06 PM

my truck is non-ac. i had to replace my leaky rad, the truck was set up with one hose going to the rad and other going to the intake. i got a new rad and it didnt have the fitting in the rad for the hose to clamp on. so i pulled the plug out of the water pump and the hose went there. works like a charm. no problems whats so ever.

Derek

**COBALT** · 10-17-2003, 02:15 PM

Yes those drawings are right. Later water pumps (and ones for AC) have a port you can use. I run a long water pump right now, and I have no port on the radiator. That's because the radiator was replaced at some point, and the engine (along with the water pump) came out of an '80 pickup which may or may not have had AC.

Since I'm used to this setup I wouldn't change it. Most of the aftermarket radiators that I'd like to use don't have a port on them, and i don't have a problem running a line to the water pump. I think it looks better anyway.

dubie · 10-17-2003, 02:20 PM

OK i need to ask another related question here. My 350 will be put in the factory V8 location rather than the inline 6 spot. I have a long water pump on this engine and a clutch fan. Am I going to run into clearance problems with a 4 core rad on this? I currently have the small (2 core??) in there but will be swapping it out. It almost looks like it might hit the rad

bpmcgee · 10-17-2003, 03:17 PM

Thanks everyone! That was just what I needed!

Dubie, go ahead -- hijack away!

Brian

10-17-2003, 12:41 PM	#1
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	Water pump/radiator question Hi, I've got a 71 blazer, manual transmission, no A/C. The PO bastardized pretty much everything in the truck, including (I think) the radiator. Right now the heater core has hose going from the intake, and another from the top of the radiator. The port on the side of the waterpump has been plugged. Here's my question -- How was this originally plumbed? The waterpump that NAPA lists for this truck has no port on the side of it for the heater core. Also, they show a 71 radiator that doesn't have a port for the heater core either! What's up with this? Thanks, Brian

10-17-2003, 01:55 PM	#3
jef5150 Inline 69 Join Date: Apr 2003 Location: valleysprings,california Posts: 1,018	pics,,,,,71chevy service manual ok,this is the way your radiator/heater core is "SUPPOSED" to be hooked up, your gonna get replys that say it doesnt matter how you hook it up ,im just saying this is how its "supposed" to be done according to chevrolet,,jeff Attached Images

10-17-2003, 02:06 PM	#4
67cst i love summertime Join Date: Jul 2002 Location: Kelowna BC Posts: 4,303	my truck is non-ac. i had to replace my leaky rad, the truck was set up with one hose going to the rad and other going to the intake. i got a new rad and it didnt have the fitting in the rad for the hose to clamp on. so i pulled the plug out of the water pump and the hose went there. works like a charm. no problems whats so ever. Derek __________________ 1967 shortbox stepside Chevy, 365 hp 327, th400. GLOVE BOX LIGHTS FORSALE, click link for info http://67-72chevytrucks.com/vboard/s...d.php?t=273724

10-17-2003, 02:15 PM	#5
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Yes those drawings are right. Later water pumps (and ones for AC) have a port you can use. I run a long water pump right now, and I have no port on the radiator. That's because the radiator was replaced at some point, and the engine (along with the water pump) came out of an '80 pickup which may or may not have had AC. Since I'm used to this setup I wouldn't change it. Most of the aftermarket radiators that I'd like to use don't have a port on them, and i don't have a problem running a line to the water pump. I think it looks better anyway. __________________ '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.

10-17-2003, 02:20 PM	#6
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,855	OK i need to ask another related question here. My 350 will be put in the factory V8 location rather than the inline 6 spot. I have a long water pump on this engine and a clutch fan. Am I going to run into clearance problems with a 4 core rad on this? I currently have the small (2 core??) in there but will be swapping it out. It almost looks like it might hit the rad __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

10-17-2003, 01:51 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	This is what my radiator man told me. Trucks with ac should have the outlet on the radiator for the heater. This does not always hold true, but I have seen it setup this way on some original installations. With these trucks over thirty years old, a lot of changes have been done to them over the years. It is not a bad thing to run the heater to the radiator as far as I can tell. Jim

10-17-2003, 03:17 PM	#7
bpmcgee Registered User Join Date: Mar 2003 Location: Northern Illinois Posts: 2,181	Thanks everyone! That was just what I needed! Dubie, go ahead -- hijack away! Brian



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.