Questions on C3 heater replacement

[Justin S.]

1970 without A/C.
1. Is there supposed to be any foam insulation on the interior facing side of the heater? It seems that the heater would rub against the metal pieces on the inside of the box and create a leak.

2. Should the plenum door move freely by hand? I can't get it to actuate by pushing on the door and the lever doesn't move either.

3. See picture of box. Should I replace the entire unit?

4. Are the beads of silicone typical from the factory?

-Justin

[Joe L.]

Re: Questions on C3 heater replacement

1970 without A/C.
1. Is there supposed to be any foam insulation on the interior facing side of the heater? It seems that the heater would rub against the metal pieces on the inside of the box and create a leak.

2. Should the plenum door move freely by hand? I can't get it to actuate by pushing on the door and the lever doesn't move either.

3. See picture of box. Should I replace the entire unit?

4. Are the beads of silicone typical from the factory?

-Justin

Justin------

The door should move freely.

No silicone was used at the factory. It had not even been invented in 1970.

Dr. Rebuild sells a heater box rebuild kit. However, your heater box appears to suffer from significant corrosion and might be difficult or impossible to restore/repair. The problem is that, as far as I know, there are no reproduction heater boxes available.

[Justin S.]

Re: Questions on C3 heater replacement

Joe,
Should there be any foam on the interior of the box to prevent any metal on metal deterioration?

[Harry S.]

Re: Questions on C3 heater replacement

https://shop.docrebuild.com/1968-1979CorvetteDeluxeHeaterBoxSealKit.aspx

From Dr. Rebuild

[Joe L.]

Re: Questions on C3 heater replacement

Joe,
Should there be any foam on the interior of the box to prevent any metal on metal deterioration?

Justin------

Note item "D" in the Doc Rebuild heater box diagram.

If you can restore the metal components of your heater box, the Doc Rebuild kit is the PERFECT solution to rebuild the heater box and return it to original configuration and functionality.

[Patrick N.]

Re: Questions on C3 heater replacement

FWIW, https://thepartguy.com in Tampa FL restores heater boxes (typically sells them <$400). If you need new metal for the internals, he might be a source, or might restore yours. (I have not used them)
My 68 internals were rotten and mice chewed the squirrel cage fan all up. I found a good used box for $100 and restored that one. I also purchased and would recommend the Dr. Rebuild seal kit.

[Jeff P.]

Re: Questions on C3 heater replacement

JAustin , I sent you a pm.

[Justin S.]

Re: Questions on C3 heater replacement

I was able to restore a heater box I purchased from David Sokolowski. I removed the metal shield and carefully pulled the half round pin to install a complete seal kit after cleaning up the plenum door etc..
I don't have the proper means of supporting the box while installing the rivets for the metal shield so I will try to use sex screws with low profile heads.

[John W.]

[Justin S.]

Re: Questions on C3 heater replacement

See pictures below. The new heater I purchased from Rock Auto is physically larger compared to the one I removed and tough to insert in the heater box. Does anyone have a good replacement part number for a '70 without C60?

Also, while cleaning the engine side of the firewall for the butyl application I found two areas where numbers appear to be embossed and stamped. The 48084 looks to be deliberate while the stamping looks to be the product of boredom by someone working on the car at some point. These numbers are below the circular cutout for the squirrel cage.Firewall 1.jpgHeater.jpgFirewall 2.jpg

[Joe L.]

Re: Questions on C3 heater replacement

See pictures below. The new heater I purchased from Rock Auto is physically larger compared to the one I removed and tough to insert in the heater box. Does anyone have a good replacement part number for a '70 without C60?

Also, while cleaning the engine side of the firewall for the butyl application I found two areas where numbers appear to be embossed and stamped. The 48084 looks to be deliberate while the stamping looks to be the product of boredom by someone working on the car at some point. These numbers are below the circular cutout for the squirrel cage.[ATTACH=CONFIG]113434[/ATTACH][ATTACH=CONFIG]113435[/ATTACH][ATTACH=CONFIG]113436[/ATTACH]

Justin------

The other characters are definitely something that was done when the panel was manufactured. They may seem "frivolous" but I'll bet they have some once-important meaning. We just don't know what it is and we'll likely never know. Just one of the mysteries of Corvette component manufacturing.

Your heater core is aluminum. I actually prefer and recommend aluminum cores like these because they have all welded construction, not soldered like original brass cores. I especially like them for cars with aluminum radiators because that keeps the radiator and heater core of the same material. However, most, if not all, of these SERVICE aluminum cores for older applications are made in China and I doubt if they're made by Tier 1 automotive parts suppliers. Sometimes, they also don't get things dimensionally right and your fitment issue is a perfect example of that.

Corvettes used copper/brass heater cores right through the 1996 model year even though Corvettes went to exclusively aluminum radiators in 1984. I really wish that C4 Corvettes had used aluminum heater cores and, preferably, the type with welded-on, aluminum tanks. However, I don't know of any OEM applications to this day that use anything but aluminum heater cores with crimped-on, plastic tanks. But, even those are preferable to copper/brass in my opinion.

[Justin S.]

Re: Questions on C3 heater replacement

Joe,
Are Modine or Go Dan still good manufacturers? I read about Spectra but have no experience with them.
My favorite radiator shop connection closed nearly 20 years ago and is all but a bygone trade here in California.

[Patrick H.]

Re: Questions on C3 heater replacement

I installed that same core in a 1972 with no major issues.
I did have to make some adjustments due to the size, but it was not a major problem.
So, your new one will work if you want it to. I talked to the guy who makes them before I bought it.

[Patrick N.]

Re: Questions on C3 heater replacement

I don't know if this is of any help to you, but I had a similar challenge and solved it this way: I made a dished cradle for the rivet head and a long rivet set to peen. With some steel bar-stock in a vise, I drilled the end to create the dish. I mounted this in a block of wood to act as a base. Similarly, I dished a second bar stock to act as the rivet set to peen the rivets. The rivets are tiny and the bar stock is not large either so the rivet set bar can be bent in an offset or double offset as / if needed to get to hard to reach rivets (Cant remember if I bent the bar - was long time ago). Not that it matters, but we design strollers from time to time and use this approach to hand rivet the tubes together. The approach worked very well on my heater box and I was happy with the results.

I was able to restore a heater box I purchased from David Sokolowski. I removed the metal shield and carefully pulled the half round pin to install a complete seal kit after cleaning up the plenum door etc..
I don't have the proper means of supporting the box while installing the rivets for the metal shield so I will try to use sex screws with low profile heads.

[Joe L.]

Re: Questions on C3 heater replacement

Joe,
Are Modine or Go Dan still good manufacturers? I read about Spectra but have no experience with them.
My favorite radiator shop connection closed nearly 20 years ago and is all but a bygone trade here in California.

Justin------

Modine has been around for a long time but I don't have any real experience with them. I know little or nothing about Go-Dan. These days, the radiator and heater core business has changed a lot. Copper/brass radiators and heater cores have been pretty much phased out of the OEM world. Most are now aluminum with plastic tanks. The tanks can be replaced but usually the radiator or heater core is just scrapped and a new one installed. So goeth the radiator service industry.

I recently bought an OEM part-numbered AC-Delco radiator for an old 1989 Cadillac Eldorado I have after it suffered a cracked end tank. I could have had the tank replaced but the radiator was original to the car which has nearly 250,000 miles on it and I've had the tanks replaced one time before. Well, the new radiator was made in Mexico. After I installed it, I discovered that it had a cracked tank. So much for quality control.