Heater woes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Patch** · 08-05-2002, 12:03 AM

Okay...I bought a 1972 Blazer, and since I've owned it, the heater hasn't blown hot. I started to tear it all apart, and then noticed that the heater hose is connected to the radiator, and the water pump......now...correct me if I'm wrong, but both of those hook-ups are pressurized...no? I can put my fingers on the heater core outlets at full engine temp, and there not even warm.
The outlet on the intake manifold is plugged off....I havent seen it this way before...Is this my problem? It seems like the water has no where to go. Help!!! Thanks.......

Hutch · 08-05-2002, 12:15 AM

My 71 had that same hook-up to the radiator before I replaced it.
The new radiator did not have a heater hose connection so I installed the hose to the water pump which was previously plugged off.
Your problem may very well be the vacuum controlled heater valve on the passenger wheel well or a plugged -up core or both.

By the way this is not the time of year to be trying out your heater unless you are trying to turn it off.

**Patch** · 08-05-2002, 12:23 AM

I yanked that water valve first thing....I live in Washington state, so I use my heater to clear up the windshield quite often....: )
I guess the only thing left to do is un-do the hose and blow through the nipples......uhh...yeah.

Hutch · 08-05-2002, 12:30 AM

you might want to check and make sure that there is a thermostat installed.

**Patch** · 08-05-2002, 12:37 AM

I did not check the thermostat.....good point. I should have....
Thanks!

johnnyp · 08-05-2002, 12:00 PM

Patch, something doesn't sound right here. You said the hoses go to the radiator and the water pump? I thought the return hose should either go to the radiator return nipple or the water pump, but not both, and the other hose should be from the manifold. Anybody else?

*Zkast* · 08-05-2002, 02:28 PM

hehe yep, good eye johnnyp!

There should be one hose coming from the intake (near the thermostat housing) to the heater core. Then from the heater core to EITHER the waterpump 3/4 fitting OR the radiator 3/4 fitting.

Basicly there is no water circulating through the heater core because its hooked up to the returns.

**Patch** · 08-06-2002, 08:26 PM

Well......took the heater hose off of the water pump...plugged up the hole, put it on the intake manifold.....and wouldn't ya know it......I got hot water flowing through the core....and nice hot air flowing through the vents.....thanks guy's.

*Zkast* · 08-06-2002, 10:35 PM

lol great news

Just in time to block the heater off so it doesnt burn you out of the cab since its summer time

**Patch** · 08-07-2002, 02:05 AM

You guy's out East are funny. I'm in Washington state....this morning, it was 47 Degrees....raining, and flat out nasty...summer???? What's that? Thanks guy's.

08-05-2002, 12:03 AM	#1
Patch Senior Member Join Date: Jul 2002 Location: Oak Harbor, WA Posts: 709	Heater woes Okay...I bought a 1972 Blazer, and since I've owned it, the heater hasn't blown hot. I started to tear it all apart, and then noticed that the heater hose is connected to the radiator, and the water pump......now...correct me if I'm wrong, but both of those hook-ups are pressurized...no? I can put my fingers on the heater core outlets at full engine temp, and there not even warm. The outlet on the intake manifold is plugged off....I havent seen it this way before...Is this my problem? It seems like the water has no where to go. Help!!! Thanks....... __________________ Patch

08-05-2002, 12:15 AM	#2
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,142	My 71 had that same hook-up to the radiator before I replaced it. The new radiator did not have a heater hose connection so I installed the hose to the water pump which was previously plugged off. Your problem may very well be the vacuum controlled heater valve on the passenger wheel well or a plugged -up core or both. By the way this is not the time of year to be trying out your heater unless you are trying to turn it off. __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS

08-05-2002, 12:23 AM	#3
Patch Senior Member Join Date: Jul 2002 Location: Oak Harbor, WA Posts: 709	Let me back-up I yanked that water valve first thing....I live in Washington state, so I use my heater to clear up the windshield quite often....: ) I guess the only thing left to do is un-do the hose and blow through the nipples......uhh...yeah. __________________ Patch

08-05-2002, 12:30 AM	#4
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,142	you might want to check and make sure that there is a thermostat installed. __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS

08-05-2002, 12:37 AM	#5
Patch Senior Member Join Date: Jul 2002 Location: Oak Harbor, WA Posts: 709	Shoot! I did not check the thermostat.....good point. I should have.... Thanks! __________________ Patch

08-05-2002, 12:00 PM	#6
johnnyp Keepin' It Stock Join Date: Aug 2001 Location: Grand Island, Nebraska, USA Posts: 554	Patch, something doesn't sound right here. You said the hoses go to the radiator and the water pump? I thought the return hose should either go to the radiator return nipple or the water pump, but not both, and the other hose should be from the manifold. Anybody else? __________________ 72 Sierra Grande - Maych Forget about "do it right the first time". Do it wrong the first time to learn how, then do it right the second time.

08-05-2002, 02:28 PM	#7
Zkast Account Suspended Join Date: May 2002 Location: Olathe, Kansas Posts: 929	hehe yep, good eye johnnyp! There should be one hose coming from the intake (near the thermostat housing) to the heater core. Then from the heater core to EITHER the waterpump 3/4 fitting OR the radiator 3/4 fitting. Basicly there is no water circulating through the heater core because its hooked up to the returns.

08-06-2002, 08:26 PM	#8
Patch Senior Member Join Date: Jul 2002 Location: Oak Harbor, WA Posts: 709	Guess What??!! Well......took the heater hose off of the water pump...plugged up the hole, put it on the intake manifold.....and wouldn't ya know it......I got hot water flowing through the core....and nice hot air flowing through the vents.....thanks guy's. __________________ Patch

08-06-2002, 10:35 PM	#9
Zkast Account Suspended Join Date: May 2002 Location: Olathe, Kansas Posts: 929	lol great news Just in time to block the heater off so it doesnt burn you out of the cab since its summer time

08-07-2002, 02:05 AM	#10
Patch Senior Member Join Date: Jul 2002 Location: Oak Harbor, WA Posts: 709	Funny You guy's out East are funny. I'm in Washington state....this morning, it was 47 Degrees....raining, and flat out nasty...summer???? What's that? Thanks guy's. __________________ Patch



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