Sealant suggestion for A/C evaporator housing

[dirtymac]

We are starting to work on our A/C system.  The evaporator housing was sealed with some kind of black sticky sealant.  The sealant at the top and front of the housing is still somewhat sticky.  The sealant at the back and bottom has hardened and become brittle.

My plan is to clean all of the old sealant off and reseal it.  One option I have found is Permatex 81158 Black Silicone Adhesive Sealant.  It looks similar similar and the description sounds like it would work.

[ArdWrknTrk]

Silicone is going to cure into rubber and glue that thing on permanently.

The black sealant comes as a tape on a glossy kraft paper backing.
We called it 'dum-dum' at the shop.

Also around the heater core necks....

Let me see about it, Will.  🤔

[ArdWrknTrk]

https://www.3m.com/3M/en_US/p/d/b40068316/

https://www.amazon.com/dp/B0BPMW7485/ref=sspa_dk_hqp_detail_aax_0?psc=1&sp_csd=d2lkZ2V0TmFtZT1zcF9ocXBfc2hhcmVk

Something like this?

How thick is the seal?

[dirtymac]

The bits that were still sticky just stretched all apart.  However, the parts that had stiffened up were probably close to 1/8" thick.

The part of the housing that connects against the firewall actually has a grooved area and it's about 1/8" thick as well.  The top, bottom, and front are all flat surfaces with about a 1/2" wide lip.

I've used butyl tape for flashing and some A/C stuff before.

[ArdWrknTrk]

So, maybe you need a little thicker than 1/8?

I'm sure if you look you can find 4mm x whatever width seems correct.

Id definitely go this route over RTV.

[dirtymac]

I checked my measurements again.  The grooved portion mightly be slightly less but it is very close to 1/8".  The flat areas are actually closer to being 3/4" wide.  I haven't found any 4mm thick tape but I have found 3/16" which is very close.

[Danny G]

Sounds like butyl tape. I'm getting ready to dive into the AC myself and am wondering if I can cut some neoprene into gaskets for these ducts and housings.

[ArdWrknTrk]

I think it was Scott that found a guy in Detroit/Dearborn that was making gaskets for him.

Not certain where that thread went, but Gary may know.
Maybe I should tag Scott to this thread? I haven't seen him in a while...

[Gary Lewis]

Detroit Muscle Technologies.  In this thread: https://www.garysgaragemahal.com/#nabble-td41105

[dirtymac]

We aren't quite ready to delve into the ducts yet but I ordered the gasket set form Detroit Muscle.  They're nice.

Three of the gaskets are foam rubber.  The other three are charcoal foam.  They have descriptions of the gaskets and images on their website.

I'm sure if you could find the right thickness of neoprene it would probably work for the stiffer gaskets.

[dirtymac]

The butyl tape worked our very well.  I noticed that some of the manufactures suggested refrigerating it for 6 hours before installing.  We did that and I think it lessened the stickiness and the amount of stretch.  It was really thick and I think we could have gotten away with the 1/8" thickness.

[ArdWrknTrk]

Glad for that!  👍

I used to wish we could do the roof deck install of ice & water shield only in the winter for the same reason.
Dealing with a soft & sticky roll of that stuff 1m by10 (3x33') in the baking sun could be a real disaster.

[Gary Lewis]

Late to the party, but that's the way I went and it has worked well.  You don't want to glue that thing together, as Jim pointed out.

And I put it on in the shop so it would have been around 74F and it didn't stick too badly.  But I can see how working with it at 100F wouldn't be fun.

[dirtymac]

We were working in the shade of the carport but it was in the mid 90's here.  We opted to install the tape on the removable portion of the housing so we could tackle that part inside the house.  It stayed pretty thick long enough for us to second guess ourselves about 10 times while we tried to fit the thing back together.  We definitely did not need the thick tape that we got.  but it was nice to see it squeeze out a bit across all of the joints.

We are still working through the rest of the A/C but we are hopeful we will have this working before the end of Summer

[ArdWrknTrk]

If you lived up here you'd have the AC fixed just in time for the first snowfall!

Thanks for the progress update.  

You've got an incredible amount of work done so far!