Last heater core questions: I HOPE.

[In The Ten Ring]

So I am figuring out how it all goes back together and I think I just about have it. EXCEPT for this little guy and a rivet question.

I don't think there was any gasket caulk between the heater core and the opening it rests against but I have this rectangular gasket that came in the GMC Paul's kit. I can't quite get it to line up.....is it necessary?

(Disassembly pic, the current state is much cleaner with a lot less rust. )



Also, I bought 1/8 inch aluminum rivets with 1/2 inch of grip area, would those work for what rivets the heater box requires? I plan on using aluminum washers on the fiberglass side.

[custom10nut]

Not to hijack, but is there also supposed th be caulk/RTV around the openings where the tubes come through?

[RodnRudy]

I took that rectangular gasket and cut it into four pieces then used 3M weather strip adhesive to glue each piece in place. It's a lot easier to fit in there. The heater core will lay up against it and act as a cushion and seal.
For the large gasket that fits around the heater box, I also used the 3M adhesive working carefully around the housing. Use the adhesive as directed and it will stick like crazy! The gasket alone is all I need to seal the housing to the firewall.
I can't say on the rivets cause I used a new housing.

[In The Ten Ring]

Originally Posted by custom10nut

Not to hijack, but is there also supposed th be caulk/RTV around the openings where the tubes come through?

That's a good question to ask though, no "hijack" worries. My heater box had nothing around the heater core tubes, I guess hot air was lost there. GMC Pauls (among others apparently) have foam plugs with holes in the center to take up those spaces although none of those sent fit my repop tubes correctly with regard to the openings for the tubes in the heater box. I could be using those wrong though.

A member sent me two foam pieces that once I trimmed a bit off, fit wonderfully. Grump Old Man (I think) is his forum name.

[Acorn]

X2 what RodnRudy said.
As far as rivets, are you talking about the brackets that hold the core in the box? If so, they are not rivets. They are hex head screws that mount from the outside in. Look closely at your brackets, they should be threaded.

[In The Ten Ring]

Originally Posted by Acorn

X2 what RodnRudy said.
As far as rivets, are you talking about the brackets that hold the core in the box? If so, they are not rivets. They are hex head screws that mount from the outside in. Look closely at your brackets, they should be threaded.

No, no, no, NOOOOOO! (OK, I'm just being silly ). I am aware the brackets that hold the heater core to the side of the heater box are held in by 4 screws, I am asking about the 4 or 5 rivets that hold the metal plates to the rear of the heater box. What gripping length rivets do I use? I plan to use a washer on the front of each rivet to help protect the fiberglass of the heater box.

[pritch]

Here's that write-up I did several years back. I'll go and look at my spare now.

http://67-72chevytrucks.com/vboard/s...d.php?t=568897

[F.A.A.benny]

Originally Posted by pritch

Here's that write-up I did several years back. I'll go and look at my spare now.

http://67-72chevytrucks.com/vboard/s...d.php?t=568897

I took a look at your write up and I have seen that bolt in the mold many times for different vehicles. Harrison must have had a reason for it. I am working on a 68 GTO a/c housing right now and it has one also

[In The Ten Ring]

Pritch,

No mention of rivet diameter or length in your thread..........although the thread was very helpful, thanks for posting it.

[In The Ten Ring]

I THINK I HAVE FIGURED IT ALL GUY FOLKS.

I may dispense with the rectangular gasket around the heater core itself.....it didn't have it before and the gasket I have doesn't want to work with the heater core repop I bought.

I had to use a round file and make two of the holes for the heater core (wire) bracket screw oblong by just about 1/8 of an inch. Now it screws together perfectly.

I am curious though, does it matter which one of the two metal pieces on the back go on top of the other? Pritch seems to have the flapper cover on top of the fan cover.....does it matter?

Still on the fence about whether or not to use the gasket that attaches to the heater core. I guess not enough of you have done this particular rebuild to be able to weigh in.

[pritch]

Originally Posted by In The Ten Ring

Pritch,

No mention of rivet diameter or length in your thread..........although the thread was very helpful, thanks for posting it.

Pretty sure I used 1/2x 1/8 like you said, but hindsight suggests that a little longer might have been better, as these were too short to use a washer with.

[ratty69]

I'm in the middle of this job myself. The core I took out ( old repop ) didn't have a gasket. After it comes back from the rad shop, that same core is going back in. Thanks to this thread I know I need to make a gasket for it.

The gasket will likely both improve efficiency of the heater and help attenuate vibrations. I'm also going to try to put something between the core and the clips to prevent corrosion.

[In The Ten Ring]

Originally Posted by ratty69

I'm in the middle of this job myself. The core I took out ( old repop ) didn't have a gasket. After it comes back from the rad shop, that same core is going back in. Thanks to this thread I know I need to make a gasket for it.

The gasket will likely both improve efficiency of the heater and help attenuate vibrations. I'm also going to try to put something between the core and the clips to prevent corrosion.

All threads have value.......even dumb questions like mine!

Pritch: I did not understand your message but the reply you gave above is more clear. Go on and call me today if you can though.

Hmm.....so 1/2 inch gripping area may not be long enough for a washer? Do you think 5/8" grip length would be enough to use a washer with? (Apparently even that is a rare size but available by order).

As for the gasket, I took the one member's advice and cut it into four pieces and trimmed the two side pieces. That allowed the gasket to fit my repop heater core perfectly. I tried to use my original core, but it had a leak that the radiator shop could not fix. I did get a brass/copper repop core though.

I don't think the side brackets can corrode, as those appear to be copper. The heater core will corrode anyway, as it is copper and will turn green to some extent. It won't rust though. (I painted my brackets with high temp engine paint).

Considering how dirty my fan blades were, tearing the heater core down for cleaning may be a good idea every 10 years or so. *I could not get my fan apart, so I used like 100 Q tips to clean it with water.

[Acorn]

Sorry I didn't understand your question earlier. (I'm a product of public skoolin!)
Just take your heater box to the hardware store and see what fits.

[In The Ten Ring]

UPDATE:

I have it together.

I used aluminum rivets from Tractor Supply, "Surebonder" I think was the trade name. 1/8" diameter x 1/2" gripping area. Now the measurement on the gripping area was more than 1/2", a tidbit most people would miss.

I used zinc-plated steel washers, 1/8" hole diameter, where I could. There was one rivet where a washer couldn't be used due to the shape of the fiberglass box.

I think a 3/8" grip area rivet might have been better but I didn't have any of those, so I went with what I had. I do think 1/4" would be too short.

Mine was put together slightly different from what Pritch shows, his had one extra rivet hole. I didn't think about it until after I had mine together; I could have put that rivet hole in myself, but it should work as is---it's how it came from the factory after all. I used the RVT silicon and 3M strip caulk as suggested.

I am letting the caulk cure until the day after tomorrow before I try to put the heater core in and put it on the front of my truck.

I meant to take pics but I forgot my camera.