POLL: Interior Heat
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,618
Likes: 7,064
From: New Or-leens Loo-z-anna
This rookie just bought a very neglected '68 convertible in need of rescuing....
I'm taking Members advice and insulating/soundproofing everything to avoid toasted toes.
I'm taking Members advice and insulating/soundproofing everything to avoid toasted toes.
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
1980 Corvette good cooling system, Jet Hot coated headers, Thermo Tech underneath floor, good AC. No heat problem.
1975 Convertible when bought had built 406 (not the one in my signature) unpainted headers, half #ss cooling system, heat came through heater when off. Floor was hot. Could roast a turkey in this car.
The Vert will be a cool ride when done.
1975 Convertible when bought had built 406 (not the one in my signature) unpainted headers, half #ss cooling system, heat came through heater when off. Floor was hot. Could roast a turkey in this car.
The Vert will be a cool ride when done.
Burning Brakes
Joined: Apr 2010
Posts: 1,018
Likes: 9
From: Winston Ga.
75 dual exhaust, no cat, otherwise stock non AC/l48. no melting feet issue but the cabin does get warm. I have installed a bypass valve and will install heat shielding and I think that will work as well as anything.
I get heat from my tranny tunnel.
I get heat from my tranny tunnel.
Thread Starter
Racer
Joined: Jul 2013
Posts: 385
Likes: 3
From: Leesburg VA
Thanks to everyone that has responded. I am actually quite surprised at the responses because I imagined that this floorboard heat issue was much more prevelent than it appears to be based on the responses. I think we are also finding out that the cause may be different for cars that display the same symptoms. F22 is on a path that I really hope works for him, and the research and items he is finding are going to be very valuable to C3 owners for years to come. I have got to get my ventilation system working adequately so that I can close off the air supply coming through the passenger side kick panel. By the way, I am not fully convinced that correcting the HVAC system will solve my heat problems, which is why I am so interested in what F22 is pursuing here.
Hopefully this will come to a successful conclusion at some point soon...not so bad now that it is cooler outside, but definitely need it fixed by next summer. I would drive my Corvette a lot more if it were more comfortable to take on longer drives. Especially now that the reliability seems to be good again.
John
Hopefully this will come to a successful conclusion at some point soon...not so bad now that it is cooler outside, but definitely need it fixed by next summer. I would drive my Corvette a lot more if it were more comfortable to take on longer drives. Especially now that the reliability seems to be good again.
John
Le Mans Master
Joined: Oct 2006
Posts: 6,842
Likes: 285
From: Palmdale CA
Good one John and thanks for posting this. We got a lot of great and upfront responses and info on this and it was truly intriguing. Some had stock manifolds (like yourself) and are still cooking. Some had headers and no problems! And the other way around too!
It's tough for the guys, without the heat problems to understand, just how incredibly hot some of our C3's get! When you've got the steering column radiating 144 degrees right underneath your feet, you're gonna be feeling mighty uncomfortable.
For others, it may be plenum and duct leakage, though, it's hard to imagine, even that being fry-baby hot! I hope we'll get there.
It's tough for the guys, without the heat problems to understand, just how incredibly hot some of our C3's get! When you've got the steering column radiating 144 degrees right underneath your feet, you're gonna be feeling mighty uncomfortable.
For others, it may be plenum and duct leakage, though, it's hard to imagine, even that being fry-baby hot! I hope we'll get there.
Le Mans Master
Joined: Mar 2001
Posts: 5,741
Likes: 645
From: Lincoln, CA
I'll post this here too.
BBC here, when I had the stock manifolds I was finding the foot-wells were pretty damn hot even with the top down. Stock heat-shields but no tranny collar or tunnel shield. Stock carpet and padding.
Changes so far. Custom coated inside and out Hedman Headers. DEI Heat shield replacing the stock fiberglass padding. Added a ball valve to one of the heater hoses.
My last hour drive on a warm day didn't get heat that I noticed.
I'll be adding a tranny collar and tunnel shield when I get the clutch done soon and I have the EZ Cool shield I'm be adding when I redo the seats.
I noticed in the other thread they are looking at the steering column. I have the Steeroids kit but I wouldn't think that would make a difference.
Down the road I plan on adding AC so I'll be sure to check every duct and door for seals.
BBC here, when I had the stock manifolds I was finding the foot-wells were pretty damn hot even with the top down. Stock heat-shields but no tranny collar or tunnel shield. Stock carpet and padding.
Changes so far. Custom coated inside and out Hedman Headers. DEI Heat shield replacing the stock fiberglass padding. Added a ball valve to one of the heater hoses.
My last hour drive on a warm day didn't get heat that I noticed.
I'll be adding a tranny collar and tunnel shield when I get the clutch done soon and I have the EZ Cool shield I'm be adding when I redo the seats.
I noticed in the other thread they are looking at the steering column. I have the Steeroids kit but I wouldn't think that would make a difference.
Down the road I plan on adding AC so I'll be sure to check every duct and door for seals.
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Melting Slicks
Joined: Sep 2011
Posts: 3,372
Likes: 215
From: Peoria Arizona
'77 - no heater hoses, AC, but compressor is not on car, ceramic coated headers, good cooling system (runs at 200 - 205 at freeway speeds). I don't have hot air blowing in, but the floorboards / footwell area do get pretty hot after about a half hour of driving. With the windows up it would be unbearable.
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
'70 350/300 coupe. I have fixed EVERYTHING on this car over the fifteen years that I have had it but for the A/C and [related] cabin heat issue. Stock exhaust, all OE parts and shields, tunnel shield, etc. are still in place and in good condition. Car does not overheat...just cooks its occupants. Living in a desert climate, I don't drive it in the summer more than a few miles at a time
I have replaced the heater valve, vacuum valve at the heater control, cowl seal at the back of the hood, and after a few minutes of running heat still pours out of the heater and AC vents in spite of the fact that the heat is turned off.
I have come to the realization that the heater/AC box seals are shot, and heat is bleeding from the hot side of the box over into the AC side and flooding the cabin with hot air, and after already having pulled the motor three times for mechanical reasons am reluctant to do it again to fix the problem. I may finally break down and resort to the Home Depot ball valve solution.
Other than that the car is perfect!
I have replaced the heater valve, vacuum valve at the heater control, cowl seal at the back of the hood, and after a few minutes of running heat still pours out of the heater and AC vents in spite of the fact that the heat is turned off.
I have come to the realization that the heater/AC box seals are shot, and heat is bleeding from the hot side of the box over into the AC side and flooding the cabin with hot air, and after already having pulled the motor three times for mechanical reasons am reluctant to do it again to fix the problem. I may finally break down and resort to the Home Depot ball valve solution.
Other than that the car is perfect!
Instructor
Joined: Oct 2013
Posts: 105
Likes: 1
From: Ventura
interior heat
I have a Cali 75 stock exhaust with the cat. Gets a tad toasty on passenger side where both sides hit the cat. Goin tru dual soon. the 76 had a metal heat shield above the cat to solve the problem.
Pro
Joined: Oct 2009
Posts: 523
Likes: 4
From: Calgary Alberta
I hope at this point you have read some of the posts on the "Interior Heat" thread. I started this poll to try to determine if certain model years have the problem and others don't. We are looking for a very specific symptom, and you will know if you have it, where after 45 minutes or so of driving you feel like the soles of your shoes are melting. I am talking very uncomfortably hot.
So, I would like everyone to pipe in here, only once, as to whether you have this interior heat issue, and what model year C3 you are driving, and whether you have headers or not. If we find that only certain model years are the problem, then we may ask for further information from those that have the issue and those that don't.
Please read the "Interior Heat" thread to get a thorough background into what has been done...THANKS F22!...and a more thorough explanation of the issues we are trying to resolve.
By the way, my 74 coupe with stock manifolds and side pipes will cook you in 45 minutes.
Thanks a million!
John
So, I would like everyone to pipe in here, only once, as to whether you have this interior heat issue, and what model year C3 you are driving, and whether you have headers or not. If we find that only certain model years are the problem, then we may ask for further information from those that have the issue and those that don't.
Please read the "Interior Heat" thread to get a thorough background into what has been done...THANKS F22!...and a more thorough explanation of the issues we are trying to resolve.
By the way, my 74 coupe with stock manifolds and side pipes will cook you in 45 minutes.
Thanks a million!
John
I have dynamat type insulation on the floors, a Dewitts aluminum rad with dual electric fans, the A/C is disconnected and not working, and the heater core is disconnected.
No heat issues anymore...
Last edited by donyue; Oct 23, 2013 at 12:29 PM.
Pro
Joined: Oct 2012
Posts: 585
Likes: 2
From: Los Angeles California
'79 stock with A/C. Experienced heat in the well and the transmission tunnel. Used Dynamat and heat shield all the way to the firewall. Doubled the heat shield around the tunnel. Heat is under control but I still feel warm air by my feet. When this happens, I turn on the A/C and problem goes away.