Heater Core Replacement- Need part

[Read]

In the process of replacing heater core on my 85c10 and noticed a broken part. I believe it's a diverter Valve link connector. It goes on the bottom of the heater core assembly box and helps control door flap. I was able to find the plastic piece replacement part but it doesn't come with the metal piece in my picture. Not sure how to get that piece of to be able to reuse or can the entire piece be order elsewhere. Any suggestions?

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[yevgenievich]

The nail pin thing just gets knocked out and reused with a new plastic piece. The replacement plastic piece was not available when I needed one so I went with my own aluminium version. Now have couple of plastic pieces laying around as well

 

[chengny]

Maybe the metal adjusting link is still in the air handler - down at the bottom of the plenum. Like this:

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There are a couple of ways to access that area. You can reach in through the riser for the dash vents (and into the door) or up through the floor heat diffuser.

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I looked around for quite a while but they are hard to source. P/N is 3027712. Oldsobsolete.com claims they have it in stock - NOS for $10:

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[Craig 85]

Another part that I have found no replacement for is the foam flap at the end of the diverter door pictured below. I pulled the staples out then cut to fit a piece of felt to fit. You can get from Home Depot. IIRC the felt extended about 1.5" past the end. I reused the staples to attach it and have no leakage around the end of the metal door.

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[chengny]

Another part that I have found no replacement for is the foam flap at the end of the diverter door pictured below. I pulled the staples out then cut to fit a piece of felt to fit. You can get from Home Depot. IIRC the felt extended about 1.5" past the end. I reused the staples to attach it and have no leakage around the end of the metal door.

Hey - great minds think alike. I renewed the seal on the end of the defrost/floor heat valve as well. I used foam insulation and bonded it to the valve damper with adhesive cement. I can't remember why that little gap bothered me enough to go through the hassle. That was 10 years ago and it is still in place. I don't know who came up with that stupid staple idea but it wasn't the best method.


Another modification that John and I came up with - to tighten the seal between the casing and flap -was to extend the effective stroke of the actuator by relocating the valve's pin to the 2nd hole in the link.

As assembled at the factory it is in the hole closest to the motor. But if the outer hole is used, the flap acquires a quite a bit more range in the upward direction (against the defrost vent opening by spring pressure when the HEAT mode is selected). Yet there is no negative effect when the DEFROST mode is selected.

Vacuum applied:

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No vacuum to actuator:

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Original gap (using inner hole):

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Reduced gap (using outer hole):

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[Read]

Thanks yevgenievich...I was able to pull out the nail pin.
Another question--the insulation(??) on the inside got damaged from the leaking heater core. Can I get a replacement piece for that section or should I use adhesive to glue it on?

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[chengny]

usa 1 industries has them. About $65:

http://www.usa1industries.com/firewall-pads/


Factory replacement die cut insulating pad that installs onto the firewall inside the cab. This pad is for trucks with AC.
Years Fit Chevy & GMC Truck 1980 1981 1982 1983 1984 1985 1986 1987


They come with all the various holes. Just poke out the ones you need.

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