Midyear heater core

[Peter J.]

My original heater core had a bead of what looks like putty around the perimeter of the core that came in contact with the mounting bracket. Anybody know what it is or a have substitute material. Thought it might be to isolate the core from vibration against the bracket but the putty sure seems like a poor choice.
Thanks

[Joe L.]

Re: Midyear heater core

My original heater core had a bead of what looks like putty around the perimeter of the core that came in contact with the mounting bracket. Anybody know what it is or a have substitute material. Thought it might be to isolate the core from vibration against the bracket but the putty sure seems like a poor choice.
Thanks

Peter----


I don't know what material was used originally. However, if you get a heater box rebuild kit from Dr. Rebuild you will have all the seals you need for the job.

Caution: many, if not all, of the replacement heater cores, including Delco, sold today are configured slightly different than originals. This is not really a problem from the perspective of "originality" since only a portion of the tubes can be seen once installed in the car. However, it does make for a challenge in FITMENT. You may have to slightly modify the heater box and/or its internal bracketry to make the new core fit.

[Brian M.]

Re: Midyear heater core

I think it was a rope like caulk.

[Stuart F.]

Re: Midyear heater core

I changed out my heater core about 5 years ago on my original 63. I went back and looked at the photos I took during the process and didn't see any evidence of calking or rope seal. However, I then reviewed the articles I used as reference and do see where they recommended use of a strip of black putty on the inner housing. As I have a box of black 3M rope seal, I believe that is what I used.

May I refer you to "Corvette Magazine" January 2003 issue Pages 90 thru 95 which has a very comprehensive article with great photos, as well as the fall 1999 issue of The Corvette Restorer, Vol 26, #2 which also has a well written article by Randy Merzdorf. There was a follow up article also by Gary H. Schisler on the subject, but I don't have the issue information as it was just a one page piece that I copied but did not note it's source.

My replacement core fit perfectly as did all the gaskets. The only problem I had was in putting it back together by myself. Even the articles tell you to have an assistant. It is hard to "sandwich" the inner and outer housings back together compressing the gaskets when you can only be in one place at a time (in car or under hood). I positioned the inner housing first and propped it in place with a roll of duct tape between it and the cross brace under the dash, then worked on the outer housing to get all the nuts on and draw it down.

Stu Fox

[Harry S.]

Re: Midyear heater core

Stu, I'm note sure that caulking or rope seal was used very often in 63. I saw no evidence on my April 63. So not having any on your car was probably ok.

Since we do not drive our C2's that often I would not use caulking or rope seal when replacing the heater core. If you had to change it again in the future I would not want to fight with breaking the seal to get the inner heater box out. There is always the possibility of breaking a tab when forcing it.

[Stuart F.]

Re: Midyear heater core

Thanks Harry. You've confirmed my recollection then - that none was used on my 63. Sometimes it is hard to tell as that area, at least on the lower edges, was full of corrsion goop from the core leak. In a convertible, I don't think you notice the leak quite as soon as with the coupe, specially if you drive it mostly with the top down in warm weather. I had already bought all the replacement parts in anticipation of changing it. The one nipple was already out of round and I could not get a tight seal on the heater hose with a spring clamp. I used to put some gasket sealer on the nipple, then clamp it with both a spiral/screw clamp and a spring clamp. Then, I'd remove the spiral/screw clamp a few weeks later - then it would hold.

Stu Fox

[Peter J.]

Re: Midyear heater core

This is caulking or seal I was asking about.

[Stuart F.]

Re: Midyear heater core

Peter;

I believe that is the caulking that transferred over from the inner housing. The picture I have of them applying it in the Corvette Magazine article I previously posted, shows them applying it to the inner housing flange and around the bolt studs. I would not apply it to the core, as it appears in your photo, rather on the housing only.

Stu Fox

[Peter J.]

Re: Midyear heater core

This is the chaulk that was between the core and the core bracket - they are screwed together as a unit before assembly. There was chaulk on both surfaces when I disasembled. I don't see mention of it in anybody's rebuild kit so I think I will reassemble without it. My thought was since it was not in the assembly manual it was put together be for arrival in St Louis, so you just have instructions on assebly of the inner and outer halves of the heater box.

[John H.]

Re: Midyear heater core

That sealer was applied at Harrison when they assembled the heater; all St. Louis did was to take the case out of the box and bolt it in the car.

[James W.]

Re: Midyear heater core

This is the chaulk that was between the core and the core bracket - they are screwed together as a unit before assembly. There was chaulk on both surfaces when I disasembled. I don't see mention of it in anybody's rebuild kit so I think I will reassemble without it. My thought was since it was not in the assembly manual it was put together be for arrival in St Louis, so you just have instructions on assebly of the inner and outer halves of the heater box.

Pete,

I recently replaced the heater core in my small block, a/c equipped '65. I bought the heater core from Paragon and the "Deluxe" seal kit from Doc Rebuild and it came with the caulking in thin strips similar to the 3M strip caulk you can buy. I reinstalled the heater core with the caulking plus a little extra for good measure. The fitment of the heater core from Paragon was excellent as was the seal kit from the Doc. The nice thing about Doc's seal kit is that you get a diagram and instructions that help identify what seal goes where. The kits you get from CC and Paragon do not have the install instructions.


Regards,

James West