Outer Heater Box hot air question? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

nerve · 12-14-2010, 03:40 PM

There is a lot of hot air coming out around the hose where it meets the outer heater box. See pic below.

Will insulating the area with some spray foam get more heat into the cab of the truck?

66skylarkpost · 12-14-2010, 04:00 PM

i'd be carefull with the spray foam, you wont want to get a bunch inside. you could just silicone or caulk it . i believe there was originaly some sort of a foam seal . when replaced the cores in my trucks , i cut a small pieces of foam matting i had to squares about 2" with couple holes to put one the inlet/outlets .

cdowns · 12-14-2010, 04:01 PM

it might help// but if the inside of the heater box is clogged up with 40years of crap there wont b much extra flow of heat into the cab

**LockDoc** · 12-14-2010, 06:18 PM

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I agree with Cliff. If you aren't getting a lot of heat out of your heater I'd be checking for debris or a mouse nest between the blower motor and the heater core... That would also cause excess air to exit around the tube.

LockDoc

cheyenne shortstep · 12-14-2010, 09:43 PM

Sprayfoam and automobiles do not mix. As suggested [and just done to my truck after a 3 yr hibernation] clean out the heater box first then use something such as seam sealer[flexible], urethane sealer or butyl tape to seal the area around the hose. I would not recommend silicone as silicone attracts and traps moisture, remember this when considering silicone for any hole filling situations.

nerve · 12-14-2010, 09:54 PM

Ok, I just gooped some Silicone around it for now...

If I don't notice any difference I'll remove the box and see what treasures I find inside! For now the heat works well, I had noticed the amount of air coming out and thought the system might be improved if I insulate...

Thanks for the tip Cheyenne Shortstep...I will note that in the future...I'd like to redo entire system in the future...

I have seen some heating/cooling systems without the outer box...any info on these? the tubes plug straight into the firewall???

Thanks again!

Hubscrub · 12-14-2010, 11:18 PM

i used this kit from Classic Parts of America (Part # 68-765) on the 67 sealed everything up nice

tumbleweed68 · 12-14-2010, 11:34 PM

i used the same kit as hubscrub and had great luck with it. It gave me the chance to clean and check the heater core for leaks plus reseal everything. If nothing else.... i would use the tape they use for a/c lines and fittings. That should do the trick!! Good luck!!

camrycurt · 12-15-2010, 11:43 AM

Quote:

Originally Posted by LockDoc

-
I agree with Cliff. If you aren't getting a lot of heat out of your heater I'd be checking for debris or a mouse nest between the blower motor and the heater core... That would also cause excess air to exit around the tube.

LockDoc

What's the best way to get access to clean everything out? Is it better to remove the outer box in the engine compartment or take everything apart under the dash inside the cab?

dznucks · 12-15-2010, 11:56 AM

You have to remove the outer box. You cant get to it from inside the truck.

to do this you will need to unbolt the passenger side hood hinge and slide it forward, carefully. I think there is also a bolt that is hard to get too because of the fender. The PO of my truck had broken the heater box flange at this location, so I didnt have to fool with that bolt. If memory serves me correctly, i think you have to drop the fender to get to it.

Maybe someone else can chime in on that one. There also might be a FAQ or thread on how to remove it.

**LockDoc** · 12-15-2010, 12:00 PM

Quote:

Originally Posted by camrycurt

What's the best way to get access to clean everything out? Is it better to remove the outer box in the engine compartment or take everything apart under the dash inside the cab?

You can clean 90% of it by taking the heater box off of the engine compartment side. Then just blow some compressed air through the inside passages. You have to drop the inner fender panel down to get to a couple of fasteners on the bottom of it. You can probably get them off without dropping the inner panel but I've never been able to get them back on....

LockDoc

ChevLoRay · 12-15-2010, 12:02 PM

Once you pull the front cap, it's not a big problem....

But, the nuts are on the outside (firewall), which attach to studs that are part of the inner heater ducting.

camrycurt · 12-16-2010, 10:12 AM

Great advice as usual. Thanks for the help guys!

mrein3 · 12-16-2010, 01:52 PM

I would pull it and clean it as others suggested. Then I would place 3M Strip caulk around that hole opening. It isn't permanent so you can still swap heater cores when yours leaks.

I keep a box of it around the shop. So far in 26 years of owning vehicles I'm on my first box. It goes a long way.

I don't work for 3M

dan76 · 12-16-2010, 02:50 PM

On the 70 I just acquired, someone (don't know if it was factory) used a substance similar to plumber's putty to seal this area. As it was still pliable (after how long?) I used leftover PP from a kitchen project to reseal this area.

12-14-2010, 03:40 PM	#1
nerve Registered User Join Date: Sep 2010 Location: NY Posts: 48	Outer Heater Box hot air question? There is a lot of hot air coming out around the hose where it meets the outer heater box. See pic below. Will insulating the area with some spray foam get more heat into the cab of the truck? Attached Images

12-14-2010, 04:00 PM	#2
66skylarkpost Registered User Join Date: Mar 2006 Location: kearney,nebraska Posts: 443	Re: Outer Heater Box hot air question? i'd be carefull with the spray foam, you wont want to get a bunch inside. you could just silicone or caulk it . i believe there was originaly some sort of a foam seal . when replaced the cores in my trucks , i cut a small pieces of foam matting i had to squares about 2" with couple holes to put one the inlet/outlets . __________________ '70 k-10 longbox- mid 70's drivetrain 350/350 487x heads 10.1:1 flowmasters ,35's 3.73's auburn posi ,rear shackle flip. '72 short stepside U.S. forestry truck, '73 455 buick,400 turbo,dropped 2"-4 1/4" ,3.07 posi,:'89 silverado 1500 ,OK truck ,5.7 holley tbi ,trick 700r4 3.07 auburn posi ,and my '66 skylark ,'73 centurion and my '84 monte carlo imca stock car Last edited by 66skylarkpost; 12-14-2010 at 04:02 PM.

12-14-2010, 04:01 PM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Outer Heater Box hot air question? it might help// but if the inside of the heater box is clogged up with 40years of crap there wont b much extra flow of heat into the cab __________________ 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

12-14-2010, 06:18 PM	#4
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,370	Re: Outer Heater Box hot air question? - I agree with Cliff. If you aren't getting a lot of heat out of your heater I'd be checking for debris or a mouse nest between the blower motor and the heater core... That would also cause excess air to exit around the tube. LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

12-14-2010, 09:43 PM	#5
cheyenne shortstep Registered User Join Date: Jul 2010 Location: Vista Ca. Posts: 2,405	Re: Outer Heater Box hot air question? Sprayfoam and automobiles do not mix. As suggested [and just done to my truck after a 3 yr hibernation] clean out the heater box first then use something such as seam sealer[flexible], urethane sealer or butyl tape to seal the area around the hose. I would not recommend silicone as silicone attracts and traps moisture, remember this when considering silicone for any hole filling situations.

12-14-2010, 09:54 PM	#6
nerve Registered User Join Date: Sep 2010 Location: NY Posts: 48	Re: Outer Heater Box hot air question? Ok, I just gooped some Silicone around it for now... If I don't notice any difference I'll remove the box and see what treasures I find inside! For now the heat works well, I had noticed the amount of air coming out and thought the system might be improved if I insulate... Thanks for the tip Cheyenne Shortstep...I will note that in the future...I'd like to redo entire system in the future... I have seen some heating/cooling systems without the outer box...any info on these? the tubes plug straight into the firewall??? Thanks again! Last edited by nerve; 12-14-2010 at 09:58 PM.

12-14-2010, 11:18 PM	#7
Hubscrub Cruzin Join Date: Dec 2009 Location: on the road Posts: 2,835	Re: Outer Heater Box hot air question? i used this kit from Classic Parts of America (Part # 68-765) on the 67 sealed everything up nice Attached Images __________________ Lime Wife's 67https://www.google.com/url?sa=t&rct=...wZEMODaS2d94u8 Back to the Fifties 59 https://www.google.com/url?sa=t&rct=...NAeStpydfrcj_U Proverbs 3:5,6 "Thanks to the Interstate Highway System, it is now possible to travel across the country from coast to coast without seeing anything."Charles Kuralt In memory of our first baby daughter, daddy and mommy love you. Danica Grace 6/26/14 Last edited by Hubscrub; 12-14-2010 at 11:19 PM.

12-14-2010, 11:34 PM	#8
tumbleweed68 Registered User Join Date: Oct 2006 Location: Colo, Iowa Posts: 41	Re: Outer Heater Box hot air question? i used the same kit as hubscrub and had great luck with it. It gave me the chance to clean and check the heater core for leaks plus reseal everything. If nothing else.... i would use the tape they use for a/c lines and fittings. That should do the trick!! Good luck!!

12-15-2010, 11:56 AM	#10
dznucks Registered User Join Date: Feb 2006 Location: Smyrna, Ga Posts: 1,647	Re: Outer Heater Box hot air question? You have to remove the outer box. You cant get to it from inside the truck. to do this you will need to unbolt the passenger side hood hinge and slide it forward, carefully. I think there is also a bolt that is hard to get too because of the fender. The PO of my truck had broken the heater box flange at this location, so I didnt have to fool with that bolt. If memory serves me correctly, i think you have to drop the fender to get to it. Maybe someone else can chime in on that one. There also might be a FAQ or thread on how to remove it.

12-15-2010, 12:02 PM	#12
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: Outer Heater Box hot air question? Once you pull the front cap, it's not a big problem.... But, the nuts are on the outside (firewall), which attach to studs that are part of the inner heater ducting. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

12-16-2010, 10:12 AM	#13
camrycurt Registered User Join Date: Jul 2010 Location: Leesburg, VA Posts: 420	Re: Outer Heater Box hot air question? Great advice as usual. Thanks for the help guys! __________________ Curt 1970 C/10, 250 L6 with Rochester BV carb, SM465 4 speed, 3.73 open rear

12-16-2010, 01:52 PM	#14
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,253	Re: Outer Heater Box hot air question? I would pull it and clean it as others suggested. Then I would place 3M Strip caulk around that hole opening. It isn't permanent so you can still swap heater cores when yours leaks. I keep a box of it around the shop. So far in 26 years of owning vehicles I'm on my first box. It goes a long way. I don't work for 3M Attached Images __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

12-16-2010, 02:50 PM	#15
dan76 Registered User Join Date: Mar 2008 Location: Salt Lake City UT Posts: 441	Re: Outer Heater Box hot air question? On the 70 I just acquired, someone (don't know if it was factory) used a substance similar to plumber's putty to seal this area. As it was still pliable (after how long?) I used leftover PP from a kitchen project to reseal this area.



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