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#1 |
Registered User
Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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Heater Help???
So, I'm trying to get some hot air blowing in my '72, and I've got a real head scratcher in the works. So far, I've flushed the block, put in a new T-Stat, water pump, and had the radiator dipped and re-built. I also flushed the heater core, which to my understanding is just an in-out, so if it flushes and water passes through without obstruction it's good right? The inlet hose for the heater core isn't getting hot. It gets slightly warm to the touch, but not hot like the upper radiator hose. I'm certain there is water flowing through it, just seems like it's not hot enough. I would think that the inlet for the heater core should be really hot. I removed the vacuum valve, and replaced with a straight through just to make sure that I had hot water running through the core. Any suggestions? I'm really starting to get frustrated with this because its supposed to be such a simple system. I've got some issues with the cables and doors inside the cab as well, but if I understand how this system works, the core should be getting hot water through it all the time, and when the blower is on, the air should be hot. The vacuum valve is to shut off the hot water going to the core, correct? Help me out here guys.
Thanks in advance. |
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#2 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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Re: Heater Help???
That has me confused too - doesn't make sense why your inlet hose isn't hot to the touch. Doesn't sound like it is flowing right. Would be a bit messy but you could always grab a 5 gallon bucket and yank the hose and see how it's flowing. Hmm.
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#3 |
Registered User
Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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Re: Heater Help???
I tried that before I pulled the water pump and took the radiator down to be re-built. I figured that there was a small chance that the water pump impeller was spinning on the shaft (very uncommon) and that water was just coming out because of gravity. Turned out that the old pump was fine, replaced it anyway. I really don't know where to go from here. My neighbor is a technician and its got him stumped as well. I don't know. The radiator shop said that it was about 25% plugged up, so I thought that could have been it. However, now it's back together will all new parts, and that hose still isn't getting hot. Any chance it's the core? I mean, like I said initially, I thought if you can run water in and it comes out with no leaks inside, then the core is good. There's gotta be someone that has experienced something similar.
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#4 |
People know me
Join Date: Jun 2007
Location: Hermiston, oregon
Posts: 840
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Re: Heater Help???
where do you have your heater hoses hooked to?
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1972 k/5 blazer CST 4X4 Crate 350, th350/205, dana44with trac-loc/14 bolt with detroit locker, 4 wheel discs 4.56s, 8" suspension lift using 73-87springs, 1" zerorate custom front crossmember, HAD CV drivelines and driveshaft e-brake, full cage, PRP seats, Full autometer gauges, 38x14.5x16 Toyo M/Ts, 16x10 Polished aluminum rockcrusher wheels 1967 longbox 4x4, Strong 400/400/208, 44/12bolt 4.10s, 6" lift, 35" Toyo M/Ts on corvette rally wheels |
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#5 |
Registered User
Join Date: Jan 2008
Location: PENDLETON,INDIANA
Posts: 271
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Re: Heater Help???
If Heater Hoses Are Hooked Up In A Spot Before Or After T-stat It Might Not Get Hot Until T-stat Opens Up??
If Hot Water Is Flowing Through The Block And Not The Heater Core You Have A Issue With The Flow To The Core |
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#6 |
Registered User
![]() Join Date: May 2006
Location: Wyman, Kentucky
Posts: 403
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Re: Heater Help???
Connect the two heater hoses together to bypass the heater core and if they get hot the heater core has to have some kind of obstruction.
I never did trust cleaning radiators and heater cores. Good Luck
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1972 GMC Jimmy, 4WD, 454 CI, 350 Turbo, 4" lift, 35" tires The math teacher said my son "Bubba" could be a mathmatical genius. cause he's got 13 fingers! |
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#7 |
Registered User
Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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Re: Heater Help???
Well, the heater hose going into the core is coming directly off of the water pump. The return line from the core dumps back into the radiator. I might try to tie them together as Rusty suggested, however, when I flush the core, water flows freely through. Is it possible that if there is even a minimal obstruction in the core, the lines wouldn't be getting hot? I would think they should be hot either way. Thanks for the suggestions, keep em coming.
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#8 |
Senior Member
Join Date: Jun 2001
Location: Shelbyville, KY
Posts: 3,269
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Re: Heater Help???
If your temp gauge is reading that the coolent temp is up there --around 180+degrees and your thermostat is in correctly--then the water pump should be pushing 180-195 degree water thru the hose to your heater. if that is not happening--it isn't your heater!! remove inlet hose to your heater with engine running---should have a gusher of water coming out HOT. Be careful and don't burn yourself.
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#9 |
Future TOTM Winner
Join Date: Aug 2006
Location: Bulverde, TX
Posts: 2,692
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Re: Heater Help???
I wonder if there is an obstruction in the hose or the water pump outlet? I believe you said the pump was changed recently, but what shape are the hoses in? Sometimes rubber hoses can implode where the inside ruptures and closes off, but the outside looks fine. Just a thought…
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72 Chevy CST K5 HIGHLANDER BLAZER Getting a 6.0,NV4500,NP205,14BFF (Currently laying all over the place in little pieces) 72 Chevy swb step-side "LS" 6.0 Here's a build thread of sorts 2002 HD2500 Crew Cab, 8.1L Allison 4x4 Daily Driver Check it out www.lsdyno.com |
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#10 |
Registered User
Join Date: Jan 2008
Location: PENDLETON,INDIANA
Posts: 271
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Re: Heater Help???
Maybe Move The Hose Going To The Radiator To The Intake
Does Not Make Sense To Me But What If You Were Getting Thet Same Amount Of Positive Pressure On Both Lines Then You Wouldnt Get Much Flow Much Like Hooking Up Two Positive Pressure Hydraulic Hoses On A Snow Plow Lots Of Pressure But No Flow |
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#11 | |
Senior Member
![]() Join Date: May 2006
Location: Philadelphia, Pa. 19454
Posts: 9,505
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Re: Heater Help???
Quote:
![]() ![]() Looping it from the intake back to the water pump mite work as well, see if that hose gets hot
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Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim Last edited by jaros44sr; 02-21-2008 at 03:57 AM. |
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#12 |
Registered User
Join Date: May 2007
Location: texas
Posts: 329
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Re: Heater Help???
Just a thought. But their is more to getting heat out of your core than the water running through it. You also have to move air through it. So if your fins are clogged up, no air can get through, and no heat. How hot a stat are you running? Also could be some of the tubes in the core are clogged. I had a blown head gasket on my burb. years ago. Put stop leak in it to get by. When I dropped the new motor in, the heater core was open to the air for a couple days. (Stop leak is activated by air.) could only get luke warm air after that. Back flushed core with garden hose, didn't clear it. New core did. They are a pain to get to, but I'd say you need a new heater core. If it's original, it's done good to last 35 years. Good luck. Almost forgot. My inlet hose didn't get hot either, due to lack of flow.
Last edited by old man jimmy; 02-21-2008 at 06:47 PM. |
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#13 |
Registered User
Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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Re: Heater Help???
These are all good thoughts. To answer a couple questions, it is a brand new pump, and 195° thermostat. It runs dead on 210°. My hoses are in decent shape and are all clear. I've flushed the whole system multiple times now and I can't believe it's an obstruction anywhere. The core could make sense if it needs ventilation and good air flow through the fins to work properly. I always just thought that if it flowed water, it was good. Is that not correct? Does it really need good air circulation through it as well? Could it just be that the inlet hose isn't going to get hot?
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#14 |
Senior Member
![]() Join Date: May 2006
Location: Philadelphia, Pa. 19454
Posts: 9,505
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Re: Heater Help???
The fins and fan are needed to move the hot air produced by the hot water, you aren't getting hot water to the core. You do have the hoses hooked up 5/8" to 5/8" and 3/4" to 3/4", rite? Do let it run long enuff to open the thermostat?
This may get messy, but I don't have any other ideas! Make sure your system is cold before you break open any rubber hose connections, 210 degrees hurts for a long time. I wonder if you have pockets of air in it??
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Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim |
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#15 |
Registered User
Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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Re: Heater Help???
Yeah, it's definitely running long enough to open up the thermostat, and the correct sized lines are hooked up where they should be. I thought maybe I had an air pocket also, but I've drained it and filled it twice now, and I'm fairly certain there's no air. Maybe the fins on the core are clogged with debris not letting them breath or whatever. If that were the case though, I would think it would run hotter, not cooler. ????
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#16 | |
Senior Member
![]() Join Date: May 2006
Location: Philadelphia, Pa. 19454
Posts: 9,505
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Re: Heater Help???
Quote:
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Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim |
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#17 |
Registered User
Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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Re: Heater Help???
Are you saying you think there's some sort of obstruction? Or are you just saying in general you'd start with the inlet hose temp? I agree if your saying chase it under the hood first, however, I've done everything I can under the hood. I'm certain there is good flow.
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#18 |
Registered User
Join Date: May 2007
Location: texas
Posts: 329
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Re: Heater Help???
When you say you flushed the heater core. Using a garden hose, right? The hose has a bunch more pressure than your pump will ever kick out. So water will flow through the core with the garden hose, where your pump don't have anywhere near that kind of pressure to push water through a clog. When your lines are hooked up, water will flow to the easiest path. So it don't take a big clog in the core for your pump to say. Heck with it, I'll just push this water the other way. From what you say. Still think it's the core. But would check everything else first. As it's the hardest one to get to. But it sounds like you've covered all the other bases. If you haven't seen a heater core. All they are is a baby radiator. Good luck.
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#19 | |
Senior Member
![]() Join Date: May 2006
Location: Philadelphia, Pa. 19454
Posts: 9,505
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Re: Heater Help???
Quote:
Since the inlet tube on the heater core is higher than the radiater cap I'm leaning more towards air bound, you seem confident in your claim of good flow. They used to sell a kit for flushing that was a 'tee'. You would splice this tee into your heater hose and flush away, then just replace the cap on the tee and be done. Let me think, this mite take awhile ![]()
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Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim |
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#20 |
Registered User
Join Date: May 2007
Location: texas
Posts: 329
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Re: Heater Help???
If water is not flowing through the core tubes, the hose won't get hot, the water will just set thier. And their is no valve in the core itself. It's just in through the tubes and out. Their is a vaccumm valve in the hose. But I think he said he alread bypassed that. An easy way to find out is to take off the return hose at the intake, stick it in a bucket, plug the intake, and start the truck. If no water their, put it back on. take the other hose off at the core, put it in a bucket, and start it agein. If you are getting water to the core, but not throught the core. You will know the problem.
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#21 |
Registered User
Join Date: May 2007
Location: texas
Posts: 329
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Re: Heater Help???
Just read and eirlier post that said your "heater hose dumps back into the radiator" You shouldn't ever have a nipple on your radiator for the hose, unless someone has put different radiator on it. It should go into the intake.
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#22 |
Registered User
Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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Re: Heater Help???
Looks like a factory radiator, however, it's not a factory engine. PO could have put a different radiator in when they did the engine. I'm leaning more towards the core now. It makes sense that the pump is not going to put out nearly as much pressure as the garden hose. I'll post a couple of pics later to show you what I've got going on. Thanks,
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#23 |
Registered User
Join Date: Mar 2003
Location: Cheboygan, MI
Posts: 998
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Re: Heater Help???
So, does one hose go from the waterpump to the core inlet and the core outlet hose go to the intake? Pics?
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Tony Johnson -- '71 Blazer w/L-31 Vortec 350, SM465, NP205, performer intake, edelbrock 1406, HEI, 4" lift, Boyd EFI tank, Vintage A/C My Blazer -- |
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#24 |
Registered User
Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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Re: Heater Help???
Ok, the first image shows the 5/8" inlet hose coming out of the water pump which goes into the heater core. It also shows the thru valve I put in temporarily so that I was sure the valve wasn't closed and hot water was getting to the core.
![]() This shows the 3/4" return line coming from the core to the radiator. ![]() |
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#25 |
Senior Member
![]() Join Date: May 2006
Location: Philadelphia, Pa. 19454
Posts: 9,505
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Re: Heater Help???
I think Ol' Man Jimmy nailed the problem, never seen a hose go to the radiator, that area over there is usually for the trans. cooling lines. Yours is A/C equipped and I am not familiar with that setup, so someone with that knowledge will have to chime in. Which leads me to another question, how do you cool your trans.? My blue hose is the 3/4" water pump to core feed... also I'm confused on the temp. bypass valve
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Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim Last edited by jaros44sr; 02-24-2008 at 11:21 PM. |
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