Heater issuses (not so hot) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71402BB · 03-09-2005, 04:19 PM

First of all I just wanted to say HI ALL. I haven't been on in a while. Now on to the problem. I recentlly had the water pump on my inline in my burb replaced. Before I had done this the heat worked ok warm but not hot. But now I'm lucky if it even gets warm. This can make it really hard to see sometimes, because the heater can't defrost the window fast enough. I'm thinking maybe it's theres a pocket of air somewhere in the system? Although I already tryed to get any air pockets in there out. I cracked the temp sensor at the top of the engine block while I poured in more coolent to try and make sure that I got all of the air that might be in my system out. So now I'm looking for some Ideas seeing that I have run out of them. Thanks in advance -Brian

71402BB · 03-09-2005, 05:32 PM

anyone, have any suggestions?

cdowns · 03-09-2005, 05:44 PM

check heater control valve to make sure it's opening all the way, also check to see if you have flow thru the heater core

**CPNE** · 03-09-2005, 05:46 PM

Might want to add this is a non-a/c system

70 shorty · 03-09-2005, 09:32 PM

I'd replace the thermostat just because it's so cheap, just to rule that out.

modifiedGMC · 03-09-2005, 09:38 PM

Join the club! My 69 doesn't put out much heat either. It has a new 180 thermostat, and a new heater core. It's warm enough to melt frost on the window but not warm enough to melt frost on me going to the truck on cold mornings. Maybe I can count on an early spring unless I figure it out.

Terry Peerson · 03-10-2005, 07:33 AM

If the heater control valve is working, you probably don't have any flow through the core. Take off the hoses and stick a garden hose (with a high-pressure nozzle) in one of the hoses and hook up to HOT water and let it flush for about 5-min (I used the hot water valve to the washing machine). Then switch hoses and flush the other way. Then, just hook everything back up. I just had to do this on my Tahoe and the air temperature increased dramatically. It may not be your problem but, it is an easy thing to do before trying other options. Also, you may want to do this outside as it will make quite a mess.

Good Luck!

TP

NPilot1975 · 03-10-2005, 10:13 AM

Do your heater hoses get warm when the engine is hot? A quick way to check for a stuck valve or a plugged heater core, is one hose will be hot and the return will remain cold. I put an aluminum radiator in my truck and the thing works so good I have to block off all put about a 3"x3" square to get heat. I agree with changing the thermostat to start.

boilerman · 03-11-2005, 03:59 AM

Had a similar problem. Lot's of air and no heat. Froze all last winter. It turned out to be the temperature cable of the heater control. It had simply slipped off the the pin on the door inside the heater box. It was a simple fix. Just pull off the plastic cover where the temperature cable disapears into your heater box and reattach the cable. Of course I didn't figure it out until Summer.

Brainchild · 03-11-2005, 10:06 AM

Since the problem worsened after the waterpump change,I'm betting on the core being plugged.Try flushing it out like was said.It's worth a shot.Easy stuff first

03-09-2005, 04:19 PM	#1
71402BB now thats a true COON DOG Join Date: Nov 2000 Location: Franconia, NH Posts: 1,977	Heater issuses (not so hot) First of all I just wanted to say HI ALL. I haven't been on in a while. Now on to the problem. I recentlly had the water pump on my inline in my burb replaced. Before I had done this the heat worked ok warm but not hot. But now I'm lucky if it even gets warm. This can make it really hard to see sometimes, because the heater can't defrost the window fast enough. I'm thinking maybe it's theres a pocket of air somewhere in the system? Although I already tryed to get any air pockets in there out. I cracked the temp sensor at the top of the engine block while I poured in more coolent to try and make sure that I got all of the air that might be in my system out. So now I'm looking for some Ideas seeing that I have run out of them. Thanks in advance -Brian __________________ current project 67 402BB stout th350 3.08's with a locker. Plan on tubs 18.5's out back! (thanks Burnsman!) 71 SWB Stepside, was a 250, now is a 402 Big Block with 4 speed and 3.73's ( was crushed by a tree, bed sold, motor pulled) was my first truck!... oh well... 72 LWB 4x4 350 4-speed 3.08's posi wearing army olive drab green (SOLD!) 68 BURB 50TH LOOKALIKE work in progress, soon to have 250-I6 with a 3-speed on the tree 4.11's and posi ( currently sitting in back yard tarped awaiting time, $$$, and lots of love!) 67 1 TON- work truck 396 sm 420 4-speed, flat bed 4.57 gears "big red" (my first landscape truck, very rusty and crusty! but still gets the job done when needed!)

03-09-2005, 05:32 PM	#2
71402BB now thats a true COON DOG Join Date: Nov 2000 Location: Franconia, NH Posts: 1,977	anyone, have any suggestions? __________________ current project 67 402BB stout th350 3.08's with a locker. Plan on tubs 18.5's out back! (thanks Burnsman!) 71 SWB Stepside, was a 250, now is a 402 Big Block with 4 speed and 3.73's ( was crushed by a tree, bed sold, motor pulled) was my first truck!... oh well... 72 LWB 4x4 350 4-speed 3.08's posi wearing army olive drab green (SOLD!) 68 BURB 50TH LOOKALIKE work in progress, soon to have 250-I6 with a 3-speed on the tree 4.11's and posi ( currently sitting in back yard tarped awaiting time, $$$, and lots of love!) 67 1 TON- work truck 396 sm 420 4-speed, flat bed 4.57 gears "big red" (my first landscape truck, very rusty and crusty! but still gets the job done when needed!)

03-09-2005, 05:44 PM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	check heater control valve to make sure it's opening all the way, also check to see if you have flow thru the heater core __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

03-09-2005, 05:46 PM	#4
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,664	Might want to add this is a non-a/c system __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

03-09-2005, 09:32 PM	#5
70 shorty Where's my beer? Join Date: Oct 2004 Location: Glen Allen, VA Posts: 1,772	I'd replace the thermostat just because it's so cheap, just to rule that out. __________________ 70 C10, shortstep, .30 over 250,Hurst shifted 3 spd parts hauler. Holley 390, Clifford Intake, Header, ported cylinder head, unknown bigger cam. 79 Corvette L82, 4 spd, black, red interior, headers, flowmasters, and unkown bigger cam. '03 Grand Cherokee Laredo, 4.0 4x4 daily driver. 165K miles, and runs great '08 Tahoe LTZ 4x4 155K

03-09-2005, 09:38 PM	#6
modifiedGMC Registered User Join Date: Oct 2004 Location: Walker Co. Alabama Posts: 474	Join the club! My 69 doesn't put out much heat either. It has a new 180 thermostat, and a new heater core. It's warm enough to melt frost on the window but not warm enough to melt frost on me going to the truck on cold mornings. Maybe I can count on an early spring unless I figure it out. __________________ If it don't fit, force it,...If it still don't fit , modify it 'till it does fit !!!

03-10-2005, 07:33 AM	#7
Terry Peerson Registered User Join Date: Aug 2003 Location: Bonner Springs, KS Posts: 311	If the heater control valve is working, you probably don't have any flow through the core. Take off the hoses and stick a garden hose (with a high-pressure nozzle) in one of the hoses and hook up to HOT water and let it flush for about 5-min (I used the hot water valve to the washing machine). Then switch hoses and flush the other way. Then, just hook everything back up. I just had to do this on my Tahoe and the air temperature increased dramatically. It may not be your problem but, it is an easy thing to do before trying other options. Also, you may want to do this outside as it will make quite a mess. Good Luck! TP

03-10-2005, 10:13 AM	#8
NPilot1975 Senior Member Join Date: Aug 2002 Location: Plymouth, MA Posts: 891	Do your heater hoses get warm when the engine is hot? A quick way to check for a stuck valve or a plugged heater core, is one hose will be hot and the return will remain cold. I put an aluminum radiator in my truck and the thing works so good I have to block off all put about a 3"x3" square to get heat. I agree with changing the thermostat to start. __________________ 1972 Blazer body...need to get a thread started for the rest of the story

03-11-2005, 03:59 AM	#9
boilerman Registered User Join Date: Feb 2005 Location: Seattle, Washington Posts: 15	Had a similar problem. Lot's of air and no heat. Froze all last winter. It turned out to be the temperature cable of the heater control. It had simply slipped off the the pin on the door inside the heater box. It was a simple fix. Just pull off the plastic cover where the temperature cable disapears into your heater box and reattach the cable. Of course I didn't figure it out until Summer.

03-11-2005, 10:06 AM	#10
Brainchild Still drivin' a Rat Rod Join Date: Sep 2004 Location: Monett Missouri Posts: 4,925	Since the problem worsened after the waterpump change,I'm betting on the core being plugged.Try flushing it out like was said.It's worth a shot.Easy stuff first __________________ Rusty Member #13872 Instead of saying.....you are a discomfort in the back of my front.....one should be able to say...... you are a pain in the a$# 71 GMC LWB 49 Chevy 85 Chevy G20 Check out my website



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