A/C Box to firewall... what to use to seal/mount ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

75stepside · 08-11-2003, 10:16 PM

i'm looking to remount my A?C box on the firewall of my project... what should i use to seal it up??? the factory uses that terrible black stuff... can i use just clear silicon? any suggestions?

thanks!

**swervin ervin** · 08-11-2003, 10:41 PM

I put mine back on with black silicone caulking. The black stuff the factory uses will work too though. One word though, the silicone is a biotch to get off if you need to. It's like glue.

75stepside · 08-11-2003, 10:43 PM

... how did the silcon you used agree w/ the paint on your firewall.... that's my primary concern...

**crossy** · 08-12-2003, 12:06 AM

I got electricians sealing putty, comes as a block, gray or black in color. it rolled real easy into a 1/4" diameter rope and then layed it on there. it sticks pretty well. when you tighten the box it squeezes out and you can remove the excess very easy. availble at nearly any hardware type store. we call it monkey Sh*t at work and it is also called dum-dum. stays pliable. DAVE

tazman · 08-12-2003, 12:15 AM

silcone will not take paint-- if your fire wall is going black use the black silcone --will blend in--the trick to remember is that you do not need to glob it on --if you look at the part that you are replaceing you will notice several flat spots and the rest will be edge runs. on flat areas you can be a little sloppy in making sure you get it covered-- on the edge runs -a thin line of silcone will work-- when you tighten the unit down there should be very small amount of silcone squeze out-clean extra off --should come out clean and no paint problems

**swervin ervin** · 08-12-2003, 12:17 AM

The silicone won't hurt the paint, but you can't paint it. Paint won't stick to it. If you wipe off the excess when you get it on, it's fine.

I like Dave's idea too. I think anything that don't dry out on you would work. If it dries out and cracks, you may have some leaks down the road.

ElGracho · 08-12-2003, 01:37 AM

They sell some stuff at Home Depot called fingertip caulk. It sounds very similar to what Dave was talking about.

Billy G · 08-12-2003, 01:53 AM

keep in mind that silicone sealer...RTV...is ACIDIC until it dries (hence the vinegar smell). Have never seen it eat paint, but will react with bare metal. I'd run a bead on the a/c box and let it 'semi-cure' before putting it against the paint. As long as you dont 'flex' it, paint will stick.

just my 2 cents worth

Billy G

Jonboy · 08-12-2003, 08:34 AM

I used butyl tape, which is used to put windows in cars with. It is like a strip of sealant, similar to what was used at the factory.

08-11-2003, 10:16 PM	#1
75stepside Proud Member Join Date: Nov 2002 Location: Pittsburgh, PA Posts: 741	A/C Box to firewall... what to use to seal/mount ? i'm looking to remount my A?C box on the firewall of my project... what should i use to seal it up??? the factory uses that terrible black stuff... can i use just clear silicon? any suggestions? thanks!

08-11-2003, 10:41 PM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	I put mine back on with black silicone caulking. The black stuff the factory uses will work too though. One word though, the silicone is a biotch to get off if you need to. It's like glue. __________________ Mike 1985 Chevy C-10

08-12-2003, 12:06 AM	#4
crossy Oh,you can't buy that new Join Date: Apr 2000 Location: Pennsville,N.J. 08070, USA Posts: 2,039	I got electricians sealing putty, comes as a block, gray or black in color. it rolled real easy into a 1/4" diameter rope and then layed it on there. it sticks pretty well. when you tighten the box it squeezes out and you can remove the excess very easy. availble at nearly any hardware type store. we call it monkey Sht at work and it is also called dum-dum. stays pliable. DAVE __________________ "been there, done that, ruined the T-shirt". 2007 LBZ GMC Sierra, ECSB 2006 LM7 RCSB Silverado 98 Vortec project. 94,3500,6.5L 4L80 81 SWB GMC POS finally gone 73 Pinto, stock, w/CragarSS's-eww LOTS of Cummins trucks. Last edited by crossy; 08-12-2003 at 12:22 AM.*

08-12-2003, 12:15 AM	#5
tazman Registered User Join Date: May 2003 Location: laughlin nv Posts: 47	silcone will not take paint-- if your fire wall is going black use the black silcone --will blend in--the trick to remember is that you do not need to glob it on --if you look at the part that you are replaceing you will notice several flat spots and the rest will be edge runs. on flat areas you can be a little sloppy in making sure you get it covered-- on the edge runs -a thin line of silcone will work-- when you tighten the unit down there should be very small amount of silcone squeze out-clean extra off --should come out clean and no paint problems __________________ tazman member of Mojave Street Rods

08-12-2003, 12:17 AM	#6
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	The silicone won't hurt the paint, but you can't paint it. Paint won't stick to it. If you wipe off the excess when you get it on, it's fine. I like Dave's idea too. I think anything that don't dry out on you would work. If it dries out and cracks, you may have some leaks down the road. __________________ Mike 1985 Chevy C-10

08-11-2003, 10:43 PM	#3
75stepside Proud Member Join Date: Nov 2002 Location: Pittsburgh, PA Posts: 741	... how did the silcon you used agree w/ the paint on your firewall.... that's my primary concern...

08-12-2003, 01:37 AM	#7
ElGracho Gentleman Jim Driver Join Date: Nov 2002 Location: Poulsbo, WA Posts: 1,553	They sell some stuff at Home Depot called fingertip caulk. It sounds very similar to what Dave was talking about. __________________ Joe '75 GMC Gentleman Jim '84 Chev C10 Short Wide - Super duper plain (manual steering, manual brakes, no dome light, no cig lighter) '85 Chev C10 Short Wide - Super plain Vortec 4.8 4L60E trans also: '81 K30, '83 C30 Crew Dually, '84 M1028 CUCV, '85 M1009 CUCV, another '85 C10 SWB, '89 R3500 Flatbed

08-12-2003, 01:53 AM	#8
Billy G Registered User Join Date: May 2003 Location: Dayton, Tx (in Old River) Posts: 286	sealers keep in mind that silicone sealer...RTV...is ACIDIC until it dries (hence the vinegar smell). Have never seen it eat paint, but will react with bare metal. I'd run a bead on the a/c box and let it 'semi-cure' before putting it against the paint. As long as you dont 'flex' it, paint will stick. just my 2 cents worth Billy G __________________ My FAMOUS LAST WORDS...."Ima Gonna!!" - 1970 GMC 1500 swb/step 250 I-6 3 spd - "The GEM" - 1976 Chev Scotsdale swb/step 350/350 - "The JEWEL" - 1982 Chev C-10 swb/step 250 I-6 3 spd - - 2001 Chev Silverado LT -

08-12-2003, 08:34 AM	#9
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	I used butyl tape, which is used to put windows in cars with. It is like a strip of sealant, similar to what was used at the factory. __________________ 1974 Jimmy- 5.3/4L80e/NP241

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