Middle dash vent air seal

[Mikes Z car]

Hi all,

How do the two middle vent parts I have marked on the drawing seal against each other? The drawing is from a 71 FSM and my car is a 70 but I imagine they would be the same on this.

I noticed a black powdery substance in that middle vent underneath the vent part that rotates. Is that the remnants of a seal that used to be there? The part on the right is a flat piece of metal riveted to the part immediately next to it further on the right.

Thanks

[EScanlon]

The black residue you're seeing is either the remains of the foam or what's left of the black "suede" or flocked finish that got applied to the inside of #31.

Additionally, the chrome center vent fits inside 31 and is held by 32 + 33...

The area where your blue line touches #31 is (was) a foam which not only sealed to part #30's metal face (which you ID'd above) but also pushed slightly up against the chrome center vent. This foam, due to age, typically disintegrates and needs to be replaced. I don't know if buying the replacement for #31 would provide it or not.

If memory serves I have a #31 untouched (because the foam that's on there will barely accept looking at, definitely NOT touching) so I'll provide pics later.

When I redid my vehicle and a couple of friends, I re-built the foam using closed cell foam strips that I cut and shaped to fit. I don't think I have pictures of the finished product, but I'll check and see.

FWIW

E

[grannyknot]

Mike, I just restored mine last month, what was sealing those two pieces and most of the rest of the heater box was 1/8th to 1/4" foam with a sticky backing. The closest thing I could find from the hardware store was the peel and stick draft proofing for older doors and windows. In some places I just used RTV sealant as it will probably be another 40 years before the next guy gets in there to refresh.

But that particular join your asking about could use 1/2" foam strip as the bellows behind it probably isn't very springy anymore and you'll need the thicker foam to keep a seal. Somewhere in the archives is a step by step heater box overhaul, can't find it at the moment but it is worth the hunt.

Chris

[jfa.series1]

Mike,

Nothing "holds" them together except the pressure of the heater control faceplate attached to the dash. The two metal tabs/ears on the bellows on #30 act as a centering function as #31 moves to it. The dust you see is the remains of the old open-cell foam gaskets used throughout the system. Try to find some thin closed-cell foam for any new seals. I found some sheets of fragile item protective wrapping and cut gaskets/seals to fit various joints. Hope this helps.

Jim

[Mikes Z car]

E,

Thanks for the idea on the foam pushing against the chrome. That might be what filled in the gap that I wound up with. Below are pictures of what I did but the gap at the bottom after installation bothered me a bit so I figured there was more to how the foam went in than what I had guessed. I would enjoy seeing a picture of the vent you have if you still want to post it.

Chris,

I hadn't thought of the bellows as being springy because they are so stiff now that it hadn't occurred to me. With your search idea I did find a heater box overhaul thread (listed below) I don't know if that is the one you had in mind, it is a good one.

Jim,

Thanks for the idea of protective wrapping, that opens up some possibilities for materials to use especially if I end up refreshing moving parts of the duct system.

Mike

Gap visible (need more foam tape?), foam tape is not sticking out far enough and is offset:

What I did that wound up leaving a gap (foam tape spray painted black later to hide better):

Foam tape I used (I glued in with glue gun glue to make it stick better):

Typing in heater for the search (instead of duct like I did) yielded other threads on this in case someone else finds this thread and wants more info:

Heater box overhaul:

http://www.classiczcars.com/forums/thread23409.html

More info:

http://www.classiczcars.com/forums/thread46605.html

Edited December 25, 2012 by Mikes Z car

[EScanlon]

Don't forget RV repair shops when looking for closed cell foam. That's where I found it in a whole assortment of widths, AND thicknesses as well as several combinations thereof.

E