C3 (72) Heater Box Repair

[Matthew S.]

I'm putting my heater/AC system back together and one of the holes in the heater box stripped. I'm not sure what the heater box is made of so I don't know the best way to repair the stripped hole. I was thinking of using epoxy but it seems too hard and would be difficult to get the screw to make new threads. Does anyone have any suggestions on the best way to repair the hole so I can thread the screw back in successfully.

Thanks for your help.

[Jim T.]

Re: C3 (72) Heater Box Repair

I assume you removed the heater core box from inside your 72 LT-1 air conditioned convertible to replace the heater core. Where exactly is the stripped hole? Heard a local radio show on home improvement/repair mention about the many different uses of dental floss. Not recommneding this as a solution but if you try it use the waxed type. On metal stripped holes wire can be used to "improve" the retention of a screw. Just depends how much retaining pressure is required on the application.

[Chuck S.]

Re: C3 (72) Heater Box Repair

Matt, I believe the distributor box inside the car is FRP fiberglass.

In your place, I would use JBWeld to fill the hole. Pack the epoxy in well to insure the old threads are filled, then clean off all the epoxy except the material inside the hole. Allow it to cure, then select a drill bit the same diameter of the minor diameter of the screw thread. Loosely assembly the box and mark the center of the hole position with a awl. Take the halves apart, mark the hole well with the awl, then drill the hole.

If possible, find a new screw with the same thread as the old, and use it to cut the new threads. Assemble the box with the old screw.

[Chas C Henderson]

Fill and use a tap *NM*

[Chuck S.]

Re: Fill and use a tap

If it's a machine screw he can use a tap; if it's a self-threading screw, (likely if he's repairing fiberglass), the thread won't match the usual taps.

[Matthew S.]

Re: Fill and use a tap

Thanks for the suggestions guys. The hole is right in the front of the heater box. It has a self threading screw that holds the center duct to the heater box. I'm going to try a small drywall anchor, one of those plastic ones. I think that a small amount of plastic in the hole might just be enough to grab the screw and hold it in place.