body and interior Heater Box To Cowl Seal Material?

[gregmharrison]

Hey All,

 

I am replacing my heater box with a rebuilt unit and was wondering what the best product might be to seal the unit to the cowl?  Thanks as always for the advice!  Greg

[nbcbird]

3M calk strip

[Hans]

Perhaps a closed cell foam tape. I think that's what I used. One advantage is it easy to remove the heater. If you go the strip caulk route, make sure you get a continuous seal. It needs to be waterproof.

[Mike Self]

DO NOT use household caulking--it'll either eventually harden and cause leaks, or it'll stick so tightly you'll never get the heater box out intact--and the subsequent owner will curse you forever.

 

Closed cell foam tape will work well if the sheet metal is in good shape (no rust or rust pits in the metal).  If the metal was rusty and left pits after you cleaned it up and painted, then I'd use strip caulk (AKA Dum-dum).  It'll fill in the pits better than the tape and will remain flexible (nearly) forever.

 

mike

[Hans]

What I like about the foam tape is that it compresses easily so you don't strain the fastening bolts. I also used it on the gas tank rim.

[jgerock]

So far so good using this weatherstripping on the tii

[nbcbird]

I don't like using any type of foam for these applications (heater box, gas tank, etc.) due to the possibility of trapping moisture and creating more rust.  Strip calk application has no seams or voids yet remains flexible, as Mike mentioned. 

Edited January 1, 2014 by nbcbird

[sclaverie]

I used Butyl Putty Tape and it worked very well.  Stays flexible and doesn't crack.  You can get it a Home Depot or an RV store.

 

http://www.vintagetrailersupply.com/Butyl_Putty_Tape_p/vts-419.htm

[Hans]

You need to get closed cell foam, which has no visible air holes. I would look for the square or rectangular shape myself. Once its snugged down, I don't see it letting much moisture through. I'd be concerned about getting strip caulk to squish down evenly around the heater flange, not to mention getting it off of moving it around. I've used it in other applications where I could press the parts together.