heater core keeps blowing out - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cruzn72 · 05-12-2003, 07:00 PM

I have a 72 gmc. The heater core keeps going out on it. I have been told that the pressure from the new water pumps blows the core out. I was also told to put a penny with a hole in the line.

Is there an electric heater that mounts under the dash that will work? It would also be nice to get rid of the ugly heater cover in the engine compartment.

http://photos.yahoo.com/cruzn72@pacbell.net

**COBALT** · 05-12-2003, 07:07 PM

You can go with an aftermarket heater. I'm sure someone here can point you to some cool ones. As for pressure you can install a pressure regulator, but remember the flow is from the intake through the core to the pump.

oldsub86 · 05-12-2003, 11:10 PM

Something isn't right. It shouldn't blow out the heater core. I think I would look for the problem.

Longhorn Man · 05-12-2003, 11:13 PM

Never heard of them blowing out.
Is there a chance that some one may be bending the 'pipe' on the intake and output on the core?
I only say that becouse I blew out a couple that way.

casey · 05-13-2003, 01:11 AM

I put a 460 in my 77 f-150 4x4 and kept blowing heater cores, I think from that high volume water pump on it, I put a H pipe in between the two heater hoses that solved it, I used copper T fittings from plastic water lines in house plumbing,two T fittings with a small peice of hose in between, I really don't think they make heater cores like they use to.

Chevy Wrench · 05-13-2003, 02:00 AM

It may be from electrolisys. Which is basicaly electricity currant in your cooling system. I have seen it happen a few times, where it actually weakens the solder joints inside the core. Try sticking the positive end of a voltmeter inside your radiator ( in contact with the coolant) when the truck is running and the neg. end to ground. If you get any readings, you have a grounding problem. Also, remember to do this with the engine cool, so you wont burn yourself when removing the rad. cap. Iam sure there are different methods and such, so this is mearly a suggestion. Good luck and let us know.
John

**COBALT** · 05-13-2003, 02:36 AM

I've seen aftermarket water pumps trash cheap heater cores. That's why I suggested a regulator. Either that or get a better heater core (there's probably one that goes with the pressure output on the pump, not to mention a radiator). Typically if you go high pressure on one thing then everything else has to follow suit in the cooling system - especially if you get a high volume pump.

casey · 05-13-2003, 10:15 AM

cobalt that reminds me when I put that 460 in with the high volume water pump, it only had a two core radiator, which I think couldn't take the water volume, so the pressure would build up, my theory anyway

XXL · 05-13-2003, 10:22 AM

Hoses backwards? As COBALT pointed out, the flow is away from the core to the pump.

As for an electric heater the "big two" aftermarket air places have one, but they say it's intended to be auxiliary, not the main heat source.

Kenneth

cruzn72 · 05-13-2003, 05:26 PM

I appreciate all of the information. I think I will just plug off the lines and drive it in the spring and summer.

casey · 05-14-2003, 02:51 AM

I did that once when mine blew, I just routed the top hose back into the water pump

05-12-2003, 07:00 PM	#1
cruzn72 Registered User Join Date: Mar 2003 Posts: 99	heater core keeps blowing out I have a 72 gmc. The heater core keeps going out on it. I have been told that the pressure from the new water pumps blows the core out. I was also told to put a penny with a hole in the line. Is there an electric heater that mounts under the dash that will work? It would also be nice to get rid of the ugly heater cover in the engine compartment. http://photos.yahoo.com/cruzn72@pacbell.net

05-12-2003, 07:07 PM	#2
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	You can go with an aftermarket heater. I'm sure someone here can point you to some cool ones. As for pressure you can install a pressure regulator, but remember the flow is from the intake through the core to the pump. __________________ '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.

05-12-2003, 11:10 PM	#3
oldsub86 Registered User Join Date: Dec 2002 Location: Canada Posts: 695	Something isn't right. It shouldn't blow out the heater core. I think I would look for the problem. __________________ 1968 Chevy - 292 with a powerglide

05-13-2003, 02:00 AM	#6
Chevy Wrench former desert rat Join Date: Feb 2003 Location: salt lake city, utah Home of the 3 M's Mormons, methlabs and minivans Posts: 320	It may be from electrolisys. Which is basicaly electricity currant in your cooling system. I have seen it happen a few times, where it actually weakens the solder joints inside the core. Try sticking the positive end of a voltmeter inside your radiator ( in contact with the coolant) when the truck is running and the neg. end to ground. If you get any readings, you have a grounding problem. Also, remember to do this with the engine cool, so you wont burn yourself when removing the rad. cap. Iam sure there are different methods and such, so this is mearly a suggestion. Good luck and let us know. John __________________ 94 Chevy Silverado Ext cab 4/6 drop w/ 18's and 2500watt system (work truck). 67 Chevy swb under const. frame off custom, 20's, bagged and a large rat under the hood,and a 1940 Chevy truck under const.

05-13-2003, 02:36 AM	#7
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	I've seen aftermarket water pumps trash cheap heater cores. That's why I suggested a regulator. Either that or get a better heater core (there's probably one that goes with the pressure output on the pump, not to mention a radiator). Typically if you go high pressure on one thing then everything else has to follow suit in the cooling system - especially if you get a high volume pump. __________________ '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.

05-12-2003, 11:13 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Never heard of them blowing out. Is there a chance that some one may be bending the 'pipe' on the intake and output on the core? I only say that becouse I blew out a couple that way.

05-13-2003, 01:11 AM	#5
casey Registered User Join Date: Jan 2003 Location: Kelowna B.C. Canada Posts: 2,048	I put a 460 in my 77 f-150 4x4 and kept blowing heater cores, I think from that high volume water pump on it, I put a H pipe in between the two heater hoses that solved it, I used copper T fittings from plastic water lines in house plumbing,two T fittings with a small peice of hose in between, I really don't think they make heater cores like they use to.

05-13-2003, 10:15 AM	#8
casey Registered User Join Date: Jan 2003 Location: Kelowna B.C. Canada Posts: 2,048	cobalt that reminds me when I put that 460 in with the high volume water pump, it only had a two core radiator, which I think couldn't take the water volume, so the pressure would build up, my theory anyway

05-13-2003, 10:22 AM	#9
XXL Señor Member Join Date: May 2002 Location: Edge of the world Posts: 5,367	Hoses backwards? As COBALT pointed out, the flow is away from the core to the pump. As for an electric heater the "big two" aftermarket air places have one, but they say it's intended to be auxiliary, not the main heat source. Kenneth __________________ Craigslist \| ebay \| Engrishtees \| www.myattitudesucks.com \| Follow me on Twitter

05-13-2003, 05:26 PM	#10
cruzn72 Registered User Join Date: Mar 2003 Posts: 99	Thanks for the info I appreciate all of the information. I think I will just plug off the lines and drive it in the spring and summer.

05-14-2003, 02:51 AM	#11
casey Registered User Join Date: Jan 2003 Location: Kelowna B.C. Canada Posts: 2,048	I did that once when mine blew, I just routed the top hose back into the water pump



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