Is my heater box blower motor gasket installed correctly? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

HeavyHauler · 02-09-2025, 07:28 PM

I am trying to install my heater box back on engine bay firewall of my 68 Chevy C10 and having some difficulty.

Do I have this big rubber round gasket installed on the box incorrectly?

It is the one that goes to the back of the heater blower motor.

Here is a pic.

EDIT: DO NOT buy Summit Racing heater box gasket set part SUM-RP22236 for 67-72 Chevy/GMC truck without AC. The round firewall gasket is too thick and will not allow you to bolt up your heater box to the firewall. The other gaskets in the kit are fine to use but you would have to buy another big rubber gasket for the heater blower area.

HeavyHauler · 02-09-2025, 10:00 PM

I am not able to find the correct heater blower motor firewall seal like the one in this video. Anybody know where I can find one?

**dmjlambert** · 02-09-2025, 10:12 PM

It may be possible for you to trim the gasket to make it have less depth. If that doesn't work, the video shows the gasket set is from LMC.

**71CHEVYSHORTBED402** · 02-10-2025, 01:49 AM

I bought mine from Classic Heartbeat, fits like it's supposed to.

**dagnabbitt** · 02-10-2025, 12:26 PM

I just installed mine, same. It's a bit annoying because it likes to fall off while you getting ready to install the box. It seems too deep to fit on the firewall but that's because you have to "schmoosh" it down: it creates a strong seal. Get it seated and press it hard onto the firewall, while someone else bolts it down.

**HO455** · 02-10-2025, 06:27 PM

I had to use contact cement to get mine to stay in place we I installed it. For more information see post 1032 in the link.

http://67-72chevytrucks.com/vboard/s...698377&page=42

HeavyHauler · 02-11-2025, 08:20 PM

I am just going to get the correct seal from LMC or Classic. Thanks guys!

HeavyHauler · Today, 12:43 PM

Here is a pic of the difference in blower motor seals. I installed my heater box very easily in under a minute with the correct seal on the left side.

As you can see the seal on the left sits flat on the surface while the seal on the right is funnel shaped. The seal on the right is alot thicker and the rubber doesnt bend as well. Also the diameter of the center hole of the seal on the right is too small and you have to really stretch it to fit the hole on the box.

**lks dcvn** · Today, 05:16 PM

Which place did you end up getting the seal that fits (left one in pic above). Do you have a link or confirmed part number for the one that fits? Thanks.

02-09-2025, 07:28 PM	#1
HeavyHauler Registered User Join Date: Nov 2011 Location: USA Posts: 439	Is my heater box blower motor gasket installed correctly? I am trying to install my heater box back on engine bay firewall of my 68 Chevy C10 and having some difficulty. Do I have this big rubber round gasket installed on the box incorrectly? It is the one that goes to the back of the heater blower motor. Here is a pic. EDIT: DO NOT buy Summit Racing heater box gasket set part SUM-RP22236 for 67-72 Chevy/GMC truck without AC. The round firewall gasket is too thick and will not allow you to bolt up your heater box to the firewall. The other gaskets in the kit are fine to use but you would have to buy another big rubber gasket for the heater blower area. Attached Images Last edited by HeavyHauler; 02-09-2025 at 08:35 PM.

02-09-2025, 10:00 PM	#2
HeavyHauler Registered User Join Date: Nov 2011 Location: USA Posts: 439	Re: Is my heater box blower motor gasket installed correctly? I am not able to find the correct heater blower motor firewall seal like the one in this video. Anybody know where I can find one? Last edited by HeavyHauler; 02-09-2025 at 10:05 PM.

02-09-2025, 10:12 PM	#3
dmjlambert Senior Member Join Date: Apr 2016 Location: Cypress, TX Posts: 3,944	Re: Is my heater box blower motor gasket installed correctly? It may be possible for you to trim the gasket to make it have less depth. If that doesn't work, the video shows the gasket set is from LMC.

02-10-2025, 01:49 AM	#4
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,374	Re: Is my heater box blower motor gasket installed correctly? I bought mine from Classic Heartbeat, fits like it's supposed to. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly guide (kit) for restoring this truck from the ground up, complete with details including full hardware descriptions. Much of the info. applies to all 67-72 GM. My build thread, with some info. about the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025

02-10-2025, 12:26 PM	#5
dagnabbitt Senior Member Join Date: Dec 2014 Location: Edmonton Alberta Posts: 1,503	Re: Is my heater box blower motor gasket installed correctly? I just installed mine, same. It's a bit annoying because it likes to fall off while you getting ready to install the box. It seems too deep to fit on the firewall but that's because you have to "schmoosh" it down: it creates a strong seal. Get it seated and press it hard onto the firewall, while someone else bolts it down. __________________ DAVE Edmonton, Alberta 1959 Apache 1967 K20 1968 C20 1970 C10 1972 GMC 2500 1981 C10

02-10-2025, 06:27 PM	#6
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,567	Re: Is my heater box blower motor gasket installed correctly? I had to use contact cement to get mine to stay in place we I installed it. For more information see post 1032 in the link. http://67-72chevytrucks.com/vboard/s...698377&page=42 __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377

02-11-2025, 08:20 PM	#7
HeavyHauler Registered User Join Date: Nov 2011 Location: USA Posts: 439	Re: Is my heater box blower motor gasket installed correctly? I am just going to get the correct seal from LMC or Classic. Thanks guys!

Today, 12:43 PM	#8
HeavyHauler Registered User Join Date: Nov 2011 Location: USA Posts: 439	Re: Is my heater box blower motor gasket installed correctly? Here is a pic of the difference in blower motor seals. I installed my heater box very easily in under a minute with the correct seal on the left side. As you can see the seal on the left sits flat on the surface while the seal on the right is funnel shaped. The seal on the right is alot thicker and the rubber doesnt bend as well. Also the diameter of the center hole of the seal on the right is too small and you have to really stretch it to fit the hole on the box. Attached Images

Today, 05:16 PM	#9
lks dcvn Registered User Join Date: Jan 2007 Location: Columbus, Ohio Posts: 4,352	Re: Is my heater box blower motor gasket installed correctly? Which place did you end up getting the seal that fits (left one in pic above). Do you have a link or confirmed part number for the one that fits? Thanks.



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