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Demar,
I noticed that you are right here in good old Terre Haute. I thought that I had bought the book about troubleshooting interior heat problems but for the life of me, I can't find it. It could have been lost in the move.
At any rate, if you ever need help working on the vette, or if you just want to get together to cruise, drop me a line.
That's what I'm looking for. I was under the dash and I can see where the hot/cold cable goes up under the center console but I can't see any doors? Could it be different on an '80? Is the door in the center there somewhere?
Also, any luck on remembering the picture of the 5/8" valve for the heater lines? I want to print it out before going to the store to find one..or two..
That looks like an ad from the 70's......"New space-age carpet to take you to the moon and back!!!"
I can actually imagine people looking at it back then and saying, "Jeepers, that is unbelievable. We'll be flying around like the Jetson's in the nineties." :lol: :lol: :lol: :lol: :lol:
ditto BigVette1. also, check all the boots on the firewall and trans tunnel: shifter (upper and lower), clutch shaft, throttle cable, hood release cable, fuse block.
If you don't have them, add underfloor heat deflectors from a 69. GM also offered clip on heat deflectors for exhaust pipes in 69.
Opinions differ on thermo wrap. Some say it's great with no porblems. Others (including my racing mechaninc) say it will accelerate the thermal fatigue failure of the pipes.
Radio shack makes a small electronic thermometer with a remote sensor. You might try one of these with the sensor at various locations in the cab. This thermal map will tell you where the hot spots are.
ressurecting an ancient thread, and adding another tidbit. to reduce the cabin heat in my c3, i've done the following:
-- checked for missing grommets in the firewall and under the shifter boot
-- installed double-layered carpet underlayment under the seats (no cashola for the foil-backed stuff)
-- replaced the missing insulation between the trans and firewall using copper piping insulation. i used two sections, one on either side of the trans fill tube. the single item made a huge improvement!
-- re-glued the errant hood gasket
i clamped off the heater hose at the uppermost hose clamp, cut the hose then threaded it and oem valve down toward the heater core. the oem hose/valve was extended outwards just behind the front wheel, with nice access. using a second clamp on the other side of the valve then releasing the first clamp let only a few ounces of coolant out. i then cut the hose, installed the new valve and 4ft length of heater hose, and threaded this back up.
when planning for replacing the heater hose valve, i noticed that the oem valve and hose were very close to the exhaust manifold. i improved on this by using pipe insulation all the way from the new valve to the heater core, and securing the hose/valve as far as possible from the exhaust manifold. am hoping to reduce heat transfer from the manifold to the coolant in the now-isolated heater hose, by distance and insulation.
i elected to keep the handle in place as a visual indicator of valve position, thinking that maybe vibration could shuffle the ball around (?)
i shortened the handle. and will tweak it if it interferes with the riser rod. i used cable ties every 3 to 4 inches along the insulation, and after looking at the pic, i'll neaten the first cable tie.
Last edited by standswithabeer; 07-03-2015 at 07:58 PM.
On my 71:
Used boiler insulation from Lowes under the carpet, heater valve shut off, trans tunnel block (often left out), plugged and replaced all firewall plugs and grommets, resealed the heater firewall plate. Put in all radiator foam, lower air dam and hood seals, with new wheel / A arm flaps.
The best solution to heat problems, disconnect the heater hoses, Very few of us need the heater. The cab will be cooler and you will improve the water flow through the Rad.
Even if you don't need cabin heat, in many parts of the country you need warm air to defog the windshield.
The 68 and 69 Corvettes came with insulation under the exterior of the driver and passengers floor panel, and the insulation also covered up about 1/2 of the engine side of the firewall. Also covered the inside of the tranny tunnel. Much of this insulation system was discontinued for 70 and up. You can still buy all the pieces from Paragon and retrofit your 70 and up. The parts are inexpensive.
Switching to the 69 factory sidepipe exhaust system also really helps decrease cabin temps since the exhaust pipes don't run underneath the cabin. I noticed an immediate difference when I installed it on my 68. When you could still by the 69 system from the factory, it wasn't all that expensive. Today, Paragon is licensed to sell the factory system...$2200 last time I looked.
update after test ride today ...
ambient temp -- 75
engine temp -- 160
steady cruise -- 55mph
blower on "low", control lever to "vent"
roof panels installed/sunny
air temp from center vent -- 88
floor temp -- 84
side panels -- 84
temp of heat distributor assy above pass footwell -- 90
my goal of having near-ambient air temp coming out of the vent wasn't met, as air temps from vents/ducts is warmer than ambient by 15 degrees.
it seems i've isolated heat getting to the 5/8 hose from the exhaust manifold a bit, as the 5/8 hose temp (prior to the valve) was 155 degrees, and the air from the center vent was about 90. heat in the somewhat confined manifold area is pretty high, because even with the 5/8 hose tucked up right against the fender, manifold heat melted a 2inch section of insulation just below the valve! temp of the 7/8 hose was also 155, that whole area is baking from general engine/manifold heat.
the good news is that by re-installing the errant hood gasket, supply air is a bit nearer to ambient. it's blown over the distribution assy that is warmed by coolant in the 5/8 hose which was reduced from 155 to about 100 where it enters the system (under the car, just behind the front wheel) by use of the shut-off valve.
the biggest improvement by far was from installing the missing insulation at the eng/trans gap. the panels on either side of the console used to get so hot that the 3M glue i used to install new carpeting over the panels used to soften up, and the carpet would loosen. very hot to the touch. that craziness is over, with temps now about low eighties.
so, a little better. according to the PO's maint records, the last a/c recharge was in 1993. maybe i'll do the r134 swap next.
Last edited by standswithabeer; 07-05-2015 at 01:32 PM.
heat from the proximate manifold was still warming up the insulated 5/8inch hose despite my efforts, so i made a change. i relocated the valve such that it's now located about 4inches from where the hose emerges from the heater core enclosure. much further away from any exhaust heat, and now under the car where passing airflow may offer some cooling possibilities.
ambient temps 80-85 today. here's some engine compartment temp readings i took following a 45 minute test ride:
center of hood insulation -- 105
air cleaner -- 145
frame, below ac compressor -- 142
ac compressor -- 141
alternator -- 149
heater hoses, near ac compressor -- 156
water pump -- 185
right side fresh air intake screen, below windshield -- 90
area just below windshield, near wiper mechanism -- 90
air coming from center vents -- 90/92
comparing temps on either side of the hood gasket tells me that the hood gasket re-glue has had a positive effect, in that temps in the engine compartment are contained there. good news!
air temps coming from center vents is very nearly the same as the supply air intake, this tells me that non-flowing coolant trapped above the shutoff is valve is cool. good news!
it seems that air from the vents is about 5 degrees warmer than ambient, and i can live with that.
forgot to mention that i have true duals, no cats, no exhaust shields under the drivers/passenger floor pans. i may shop around for some exhaust wrap (the laced stuff) when i get a chance.
03-18-2002, 07:09 PM
Re: Cabin Heat - Curse of the C3 (mrvette)
with above,
