Rubber Seal

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

custodian

Full Access Member
Joined
Apr 15, 2016
Posts
998
Reaction score
648
Location
Catawba
First Name
William
Truck Year
1973, 1985, 1986
Truck Model
C10, C30
Engine Size
5.3 LS, 350, 454
I replaced my heater core in my 73 today. I noticed when I replaced the inside heater box that there was a gap between the heater box and defroster duct work. Is there supposed to be a rubber seal between the two? When I removed it, I did not see anything on top the box.

Also, just want to make sure that the 3/4" hose goes to the water pump and the 5/8" hose goes to the intake. I have heat only on this truck.

My truck originally had a 250 6 Cylinder, now has a 357 V8.
 

chengny

Full Access Member
Joined
Feb 22, 2012
Posts
4,084
Reaction score
1,029
Location
NH
First Name
Jerry
Truck Year
1986
Truck Model
K3500
Engine Size
350/5.7
Can't tell you for sure, but the parts dwg/list makes no mention of a seal at that joint:

You must be registered for see images attach


Also, in my experience (and that of several others), it appears that - for some reason -the gap is there by design. The 81- 91 HVAC systems all have it:

You must be registered for see images attach
You must be registered for see images attach
 

custodian

Full Access Member
Joined
Apr 15, 2016
Posts
998
Reaction score
648
Location
Catawba
First Name
William
Truck Year
1973, 1985, 1986
Truck Model
C10, C30
Engine Size
5.3 LS, 350, 454
Thanks for the diagram. I do see a piece that I don't have, the outlet assembly, #14 on the diagram.

What I did for the gap was to put aluminum tape around it.

The heater and defroster works fine now.
 

yevgenievich

Full Access Member
Joined
Mar 1, 2014
Posts
4,821
Reaction score
3,413
Location
Place
First Name
Name
Truck Year
Year
Truck Model
Model
Engine Size
Size
Mine hase foam filling the gap, tape also works
 

CRM

Full Access Member
Joined
Jun 6, 2016
Posts
1,188
Reaction score
2,776
Location
Pasco, Washington
First Name
Casey
Truck Year
1985
Truck Model
K2500
Engine Size
350 CI
I've wondered the same thing ever since I replaced my heater core. I thought I hadn't put it back together correctly.
 

BiggG74

Full Access Member
Joined
Feb 1, 2015
Posts
81
Reaction score
5
Location
Pasco Washington
First Name
Gilbert
Truck Year
1976
Truck Model
GMC
Engine Size
350
I changed my heater core this past fall and it had a material that had a type of insulation on cardboard backing that fit all the way around the box. It tore when I removed it. It got hooked on one of the bolts.


Sent from my iPhone using Tapatalk
 

Forum statistics

Threads
45,574
Posts
986,672
Members
38,664
Latest member
wilson79
Top