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Heater box and plenum repair

urchinhead

urchinhead

Basic User
Member
City
San Francisco
State
CA
Does anyone know what type of plastic the heater box and upper air plenum are constructed of?

I did some research, and a few tests. It sinks, and it burns an orange color from the small sample I sacrificed.

I can’t find any evidence of fiberglass. Could it be PE plastic? I would like to buy filler rod and weld, but perhaps I should resort to JB Weld plastic bonding epoxy to fix the small cracks and deformations.

I found the part number inside the plenum after drilling out the rivets ( pictured )IMG_5553.jpeg, but my search has returned nothing.
 
How badly damaged is it?
Here is a post with some info:
RockTractor

Post in thread 'Heater Box Repair'

Here is where I ended up....

I cut three lengths of bailing wire that were just a bit wider than the hole. Then, from the backside, I used a soldering iron to heat up the wires and sink them into the plastic so that they spanned the hole in three different places. The idea here was to give something for the filler to "grab onto".

Next , I wrapped a piece of flat steel with wax paper and clamped it to the inside of the heater box at the hole location. I leveled the heater box, filled the hole with black JB-Weld Plastic Bonder, and let it dry.

After it was dry, I sanded it down, filled...
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I did find that thread in my search. It’s not that bad. It looks like a couple rivets went in wrong at the factory, so there were a couple gaps and there are some cracks right at the rivet locations for the air intake plenum.I’ll probably find a few more things to fix when I get further along with the heater box.

Any educated guesses on the plastic type or what would be a compatible filler?
 
J-B Weld makes a lot of different material specific products now (compared to the old days), maybe contact them with the info you have and they could point you in the right direction.
Someone at one time recommended the J-B Weld PlasticWeld for a plenum but I'm unsure if they had actually used it.
 
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