I recently acquired a 79 - trying to get it back in shape. I've gotten to the point where I can drive it now :) But I notice that seems to be excessive heat in passenger area after driving for a while, say over 30 minutes. Thermostat is new, water pump new, gauge appears to be accurate at 180 degrees. Am I to deal with this, or are there some things to check??
Thanks in advance for suggestions & help

 

Probably the heater core. I recently bypassed mine and temp dropped dramatically in the cabin. Your '79 most likely has an automatic cutoff. Maybe its gone bad?
good luck!
-terry
ps: anotehr topic going around now: http://forums.corvetteforum.com/zerothread?id=324188


[Modified by terryrudy, 7:13 PM 6/18/2002]

 

This is a fairly common problem. The other poster is correct, but it probably could use some additional insulation as well. There's a pretty good book out called "A/C strategies for the 68-82 Corvette" that covers this problem in depth. It's available from most book sellers as well as Motorbooks International. The same guy also does a wind noise and water leak book.

Hans

 

I agree with Terry. I just went through this as my heater core went bad. Instead of changing it right now, I bypassed it. What a world of difference in the cockpit. It's almost like having air compared to what it was like. (Note: I DO have air but it isn't working either) :cry
Good Luck !!

 

IT probably is just a corvette thing. My 78 is in good shape and has an inch of heat sheild under the carpet and it still gets hot over there.

 

Has anybody used the silver-foil-bubble-wrap lookin stuff from Lowes? I wonder if that will do the trick? I'm puttin the carpet in on the weekend.

 

I have used the foilwrap on a '72 and '81. It's not the insulation, it's the car or something was wrong with the '72. My wife had to ride with her feet on the dash. The '81 is comfortable, not heat problem.
I was pleased with the foil insulation. I think it was quieter and cooler. I took all the carpet out of both cars and put insulation everywhere. I picked up this tip on the forum after I did mine. Use that metal looking tape that heating and cooling guys use to seal the joints in the insulation and help hold it in place. I also took of the door panels and insulated them. Not sure about the 72, seems like i did not have enough room. I even did the hood on both cars. Wish I had a pic. The under hood insulation looks great. The 72 was dark blue and had cracking and blistering paint, I thought insulaton might help prevent it. I used the small roll. I think it is 16 inches. Fits perfectly. It has a crimped edged and I just joined those in the center. Looks really sharp with the hood up. I used some left over weather stripping glue dot hold it in place.

When I took the door panels off of the 81 the plastic shell was cracked in several places. WE had some left over wood veener from a kitchen cabinet remodel. I beleive it is 1/8 inch thick. I cut it to fit the door, cut out the openings for handles, lock, etc, screwed the veener to the door liner, covered it with foil and put the panel back on. Much quieter. Tighter sounding.

Back to the heating problem. I think you have to stop the heat from coming in through the cooling system. There are several threads and comments about that, just have to find them.

 

It is a Vette thing. Exhaust pipes 2" below a fibreglass floor - heat. Here are the things to do.

1. Install a water block off valve for the heater flow. No need for 190 degree water by your feet.

2. Take out the carpet and glue down the foil backed bubble stuff nsulation pad. The stuff from Menards, Home Depot, Lowe's etc works fine. Use 3M spray glue on the floor and back side of the insulation, press it into place and cut with a razor blade. Doubt is your carpet pads will fit anymore. I had to strip off the padding. That's ok as the insulated bubble pack takes up the space. You can get the precut stuff from the Vette catalogs, but this way is far cheaper and from what I have seen is the same material.

#1&2 will drop the cabin temp by 20 degrees.

3. Make sure you have the transmission heat insulator in place. It mounts over the trans. With some real PITA yo can get one in without pulling the trans. if you don't have one.

4. There is a foam collar that fits on top of the bell housing or top of the trans behind the engine that you press into place.

5. Wait till dark and shine a bright light under the dash and then look into the engine compartment. If you see light these are holes that need to be plugged. Use plumbers putty works great. A hole the firewall from old packing that fell out draws heat into the cabin.

These things will make the cabin very comfortable as a Vette goes and the A/C works well now.

 

I installed foam collar on my 75 and solved all my interrior heat problems.Found out about it here on the forum.

 

Stewart, I used it in my 81. Works well, cut out the heat, and deadens a lot of noise. I will add it to the back of the door panels too. Get some FSK tape, it is silver like chrome, HVAC $3 a roll and this will allow you to make the seams dissapear. Don't use duct tape, it is not the same. I highly recommend Reflectix from Lowes. You will instantly notice the difference.

 

thanks for all the tips!