Heater box foam

City
Raleigh
State
Nc
#1
Can anyone tell me where to find the foam for the blend door and mode doors inside the heater box? I cant find it anywhere. I saw a write up on another website, where the guy used waterproof poly foam with adhesive backing, and it comes in sheets, but i cant find it. Called an hvac supply store, plumbing store and a construction supply store, no luck.

Thanks
 

walkerhoundvm

Typical Know-it-all
LIFETIME
CJ-8.com Member
City
Cave Creek
State
AZ
#3
Ace or True Value will have some things that are similar in the door/window section. Usually like $10 for a 10' roll or something.
 

Cmath

Scrambler Enthusiast
LIFETIME
CJ-8.com Member
City
Woodstock
State
Ga
#4
McMaster-Carr has all kinds of things for things. Look under "Raw Materials" and there are a bunch of insulating foams and plastics that come in sheet form.
 

joshvt

Scrambler Enthusiast
LIFETIME
CJ-8.com Member
City
charlotte
State
nc
#6
I just finished rebuilding my heater box this weekend. Did the blower motor upgrade and wasn't happy with the foam mentioned on the other forum for the piece that seals the motor where it goes through the firewall. Check out minicell foam used by kayakers. It's very similar texture to the original, is available in different thicknesses, is easy to work with and it's cheaper than the McMaster Carr options- I got a 12x12 piece for $5 from the local paddling/ outdoor shop. I ended up building up the seal from (3) 1/4" pieces after trying a 1" thick piece and finding out it was too thick. I also used this for the foam between the heater core and the plastic housing. It worked great. HEATER BOX 1.jpg
 

walkerhoundvm

Typical Know-it-all
LIFETIME
CJ-8.com Member
City
Cave Creek
State
AZ
#7
I ended up building up the seal from (3) 1/4" pieces after trying a 1" thick piece and finding out it was too thick. I also used this for the foam between the heater core and the plastic housing. It worked great.
Protip - you can use the omix seal for the blower by removing the collar on the rear of the motor. Mine just slid right off and the foam seal slipped right on.
 

joshvt

Scrambler Enthusiast
LIFETIME
CJ-8.com Member
City
charlotte
State
nc
#8
Are you sure that works for the blazer blower motor upgrade? The blazer motor seemed like it would be a good bit larger in diameter than the stock motor, even with the metal collar removed.
 

joshvt

Scrambler Enthusiast
LIFETIME
CJ-8.com Member
City
charlotte
State
nc
#11
Wish I had know that- would have saved me some time. When you remove the metal bands Do you still have to enlarge the fire wall hole? What are those metal bands for anyway?
 

walkerhoundvm

Typical Know-it-all
LIFETIME
CJ-8.com Member
City
Cave Creek
State
AZ
#12
Wish I had know that- would have saved me some time. When you remove the metal bands Do you still have to enlarge the fire wall hole? What are those metal bands for anyway?
Haven't gotten to that step but I imagine it'll have to be enlarged a scoche. Not sure what it might be for, perhaps it's built a certain size and then that collar helps to get it to fit a gm-specific cut-out? It really served no purpose that I could see. There's no hole or anything it's covering up, and ground is achieved through the mounting screws.
 

joshvt

Scrambler Enthusiast
LIFETIME
CJ-8.com Member
City
charlotte
State
nc
#13
Other posts I read recommended a 3.75” holesaw for the bigger motor. Seemed like it was going to be tight so to give myself more room for error I used a 4” holesaw. It was larger than necessary, but gave me some room to get everything lined up. I don’t think that seal would span the 4” hole. With the plates removed a 3.5” hole might work.
 

walkerhoundvm

Typical Know-it-all
LIFETIME
CJ-8.com Member
City
Cave Creek
State
AZ
#14
Other posts I read recommended a 3.75” holesaw for the bigger motor. Seemed like it was going to be tight so to give myself more room for error I used a 4” holesaw. It was larger than necessary, but gave me some room to get everything lined up. I don’t think that seal would span the 4” hole. With the plates removed a 3.5” hole might work.
You're right. I forget what I measured it as, but it's a tad larger than original.

I had one in there with the collar on that I installed several years ago, but it was starting to get rusty. While I'm rebuilding, I went ahead and replaced it. I was kinda surprised the collar could be removed. I think I dropped it and it came right off.
 
City
Raleigh
State
Nc
#15
Thanks for all the tips. I am using the larger blower. Im going on a hunt tomorrow to find the foam and finish the box this weekend. Thank you all.
 

joshvt

Scrambler Enthusiast
LIFETIME
CJ-8.com Member
City
charlotte
State
nc
#17
That probably works for the flap seals, but it’s I don’t think that’s what you want for the firewall seal. From the McMaster Carr description:

“...Foam has open-cell construction, which allows water, air, and gases to be absorbed.”

Since this foam is exposed to the engine compartment, I think a closed cell foam would be needed. Minicell foam is closed cell, heat resistant and chemical resistant. And it’s cheaper. Or just use the Omix seal per walkerhound.
 
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