SGTCrowley

I love my 1979 Corvette! I mean, I LOVE IT!!! It's my 5th Corvette!

But I must say, as cool as I feel driving it, it is a damn HOT ride in Phoenix with no AC (has a leak) and with the engine running on the hot side. It does better on surface streets. It just can't handle freeway RPM's!

Are the 1979's Temp gauges any good? Someone told me they weren't dependable. I was thinking of a Cobalt Gauge, not sure if it fits in the dash.

I am going to order an aluminum radiator and electric fan kit off of Eckler. I guess it replaces the stock fan coming off the engine? Has that worked well for anyone? Would love to see some pics of radiator and water pump upgrades!!

SH-60B

I can't tell from your pic, but if the air dam is missing it will get hot on the freeway. Had the same problem with my '79 and the missing air dam was the reason.

SGTCrowley

Thanks!! I will look into that. It still heats up on surface streets if I run it at all. I have to take it real easy.

7T1vette

If your gauge is working, the gauge is fine. Now, the sending unit might be 'toast'...or junk....or badly calibrated; but if the gauge is working, and the readings are incorrect, blame the sending unit.

Check out Willcox site for tutorial on checking out the temp gauge/sending unit on a C3. You will most likely find the info you need there to check out your temp circuit and find your problem.

P.S. I spent 5 years near Phoenix with my '71. It ran a bit on the hot side, but never boiled over on me. Make sure your vacuum advance can is plumbed directly to "manifold" vacuum source....NOT ported vacuum from the carb.

Your engine can run hot for a number of reasons. Your interior can be hot for an equal number of different reasons. Both need to be addressed for you and car to be "comfortable" in Phoenix summers.

AzMotorhead

Give me a shout when you're ready to get the air working

CMEPASS

Well get ready for some sticker shock when ordering a radiator. Mine is a becool in my 81 and it was not cheap. I have a restrictor plate in place if a thermostat and a Lincoln Mark VIII fan in mine. When it comes on you can see the engine temp go down. But if you go with the Lincoln fan you will have to get a controller that can handle the current and upgrade your alternator also.

jb78L-82

The 78/79 C3's especially the L-82's are notorious for running very hot-like 240 with the A/C on in very hot weather and especially on the highway with revs. My 78 L-82 A/C car ran 225 routinely when new and easily 240 on the highway with the A/C on. GM made numerous changes to the cooling systems from 78 to 79 to address the heat issue.

1. Changed the 12 O'Clock position on the temp gauge in 79 from 200 to 220 on the 79-owners complained that the gauge on the 78's was always way past the 12 O'Clock position!

2. Added a 4 inch flexible rubber extension to the front air dam (which is very small on the 78's) to those 79's with heavy duty cooling. You can see my factory rubber extension below:



3. Added an electric auxiliary cooling fan INSIDE down low below the mechanical fan inside the fan shroud to aid with pulling air through the radiator in high cooling system demand conditions.

I chased this issue for 20 years on my 78 and changed and tried many tricks until I finally found the resolution. So what can you do besides the obvious?

1. You don't need electric fans! Get a mechanical L-82 fan for a 79 with A/C-it has more blades and the correct pitch.

2. Get the 4 inch flexible rubber extension and add it to the factory front chin spoiler.

3. Get a GM thermostatic fan clutch rated for 180 degrees, NOT the 195 degree fan clutch.

4. Install a high quality aluminum radiator-I have a Dewitts

5. Install a high flow water pump with a high flow thermostat-I have an aluminum Stewart Stage 2 water pump with a HP Robertshaw 180 degree thermostat.

My 78 L-82 never goes over 180 degrees regardless of the weather and speed I am going now.

Hope that helps!

gcusmano74

Also, all the blocking for the radiator and shroud needs to be in place. The blocking forces air to flow through the radiator.
The factory system will work well, unless you have made some serious horsepower mods under the hood.
I put self sticking heat shield wrap in the trans tunnel in front of and beside the factory insulation and above the exhaust pipes. It helped to keep some of the heat out of the cabin. Of course, wash the underside well first, or nothing will stick.

jcloving

If you want to keep the heat out of the cabin:

Install a cutoff valve on one of the lines to the heater core.
Make sure all firewall plugs are in place, especially the speedo grommet.
Put in reflectix or similar insulatation on firewall, tranny tunnel and floorpans. Lots of work but worth it.

I did all these things and it keeps the SBC heat in the engine bay where it belongs. Then I got the AC blowing cold...

7T1vette

The most common source of cabin heat is that the rear hood seal allows engine compartment (hot!) air to leak and get immediately injested by the air intake port in the cowl area. While driving, change heater/vent settings so that the kickpanel door(s) are "open" then "closed". If it feels warmer when those doors are "open", that hood seal is "toast".

mk's78

Could someone show/explain where I should be looking for my 78 "rear hood seal"?????? I'd like to check mine out.............

Thanks............

Dumb question I admit....I just gotta ask..............mk's78

mrvette

I have driven my '72 convertible at various speeds, I have a BB hood scoop that has been all cut out under it, so the hood is rather light weight, not that it matters to this discussion, just for visualization comment, and so have put yarn/strings in various positions, and note that there is NO airflow through the open rear of the bulge, OR through that rear of the hood, nothing, yarn is still at 80 mph....now there is ONE huge change, I have dual Spal fans, laid flat to the radiator, so airflow under most any circumstances is directed to the front of the crank/cross support, not UP into the engine bay like a stock fan MAY DO....I have not checked with a stock fan, so dunno....

NOW, the best thing for any vette, is to seal that cowl/outside air door closed, release the spring, and use RTV to seal it shut, and remove the inside door behind the right kickpanel.....plug the vac line, obviously....

HUGE increase in cooling even here in Florida on 100f/100% days in traffic setting at a light.....that and the C4 blower to get some air moving.....OH, my a/c runs on 134 with stock condenser but manages to put out 60f air at MOST during max load times, I have a button temp gauge in there....and it's correct, because I check this stuff....

SGTCrowley

Confirmed! It is missing! Ordered one off eckler's! Thanks for the tip!

SGTCrowley

Thanks! Good Checklist! I did the Heater Core cut-off valve. That helped, but there is still heat roasting my toes!

garygnu

I have a thermostat housing with a filler cap on it ,it makes bleeding all the air easier . do you have a water pump with a swirled impeller ?I run a 6 blade plastic racing fan.what size pulleys do you have for the water pump ?consider some exhaust wrapping for the pipes under your feet .

SGTCrowley

I had already ordered a radiator and fan kit from eckler. I also got a new performance pump, and the front air dam.

...so I have plenty to do!