First time posting, however I have been reading the forum a lot and have some questions regarding the cooling system. For my 1979 L-82 with A/C, should I install a 180° or 195° thermostat? I live in Florida, and as expected it is VERY hot in the summer. Along with the thermostat, which temperature/year fan clutch would be recommended? I am looking for the best cooling and optimal engine temperature. Thanks in advance.
Have attached the photos as requested. I have bought a rebuilt ac delco water pump. I flushed the radiator once with Prestone, rinsed until clear, and a second time with Prestone and Evaporust. Ran it for several days before draining. Rinsed it multiple times until water flowed clear. Water was flowing well through radiator when looking in cap hole while engine running. My shroud does not have the springed door. Should I patch it?
Thanks again.

 

The thermostat doesn't control cooling temp it just opens at a set temp to allow coolant to flow through the cooling system. Install the OEM recommended cooling parts and you should be fine unless there are a lot of modifications to your car. To answer your first question install a 180 deg stat and only than if you think the one already installed is bad or missing.

 

Your thermostat controls the temperature of the engine at a near steady temperature. So, a 180* will keep your engine at a temperature of 180* give or take a few degrees. A 180* stat is a good choice. If someone tells you to put a 160* to cool your engine, it won't unless you change your stock radiator to a high performance aluminium type. But a 160* stat will also lower the effective working temp of the oil. I would keep the fan clutch and Hayden makes a good replacement. If you still have the original rad, its probably not working at 100% anymore. If anyone recommends to you to put a hole in the stat to help cooling, tell them they are full of ****! This is only done if an after market water pump does not have a bypass.

 

Florida,. 160 Milodon stat for sure your oil temps will be fine, its hot enough out there
Im in Ca, been running this combo since the 80s, its pretty foolproof.
Stock fan ok this ones even better, dont know the right diameter. Quiet weighs a few oz moves lots of air. Less stress on your water pump
If you really wanna upgrade any aftermarket alum. radiator will do. Night and day to your system now
https://www.summitracing.com/parts/f...caAkfxEALw_wcB

 

Not really, the 180* thermostat will open when the coolant reaches 180* allowing coolant to flow from the block to the radiator for cooling. What happens after that is dependent on the condition of the cooling system, engine condition, timing etc. The engine coolant temp could climb to 235* and the 180* installed thermostat would have no control over that. I guess if you were driving in sub zero temps and the coolant dropped below 180* than the thermostat would close but in general terms no C2 or C3 Vette is running at below 180* steady state.

There are always exceptions and I sure someone on this forum has a Vette that runs at 150*

 

i have your car..
you should already have a very big fan and (5 or 7 don't remember) blades.. AND an electric fan puller that comes on @ ~230f (kinda ridiculous) but you can bypass it to run and help cool. that's a lot of air movement.. and of course seals are critical
i run 180f
i also went dewitts aluminum radiator as my original was marginal.

pics of what you got may be helpful, and inside of radiator..
My original 40 yo radiator replacement 79 l82 - CorvetteForum - Chevrolet Corvette Forum Discussion


https://www.corvetteforum.com/forums...ss-option.html

edit.. be sure your bottom spoiler is in place too..pic under would be good too..

Coolant concern question 79 L82 m - CorvetteForum - Chevrolet Corvette Forum Discussion

 

I know you believe what you posted but sorry, your wrong. Go read up on how a stat works. You'll discover that it begins to open before 180* for a rated 180* stat and will not fully open until a temperature above 180* is reached. There are reasons for this design which hopefully you'll discover and understand how a cooling system actually works.

 

Don't forget to get Lars papers on timing......which is one of the #1 causes of a Vette running too hot.......

Jebby

 

I have a 78 L-82 and before I went about all of my mods, I did a pretty thorough job going through it due to all of the stories I heard about cooling (and A/C). I live in NC, so we get some pretty good heat in the summer. Here's my list of items to check:

• Jebby makes a great point on timing, and Lars' paper is just good stuff, so definitely work through this.
• I used a 180 thermostat just to give myself some headroom in terms of running in hot weather with A/C on
• Flush or check your radiator
• Check your lower coolant hose (from radiator to water pump). A really good one of these will have an inner spring, but even if it doesn't, check to see how soft it is when the engine is up to temp. That's the suction side, so if the hose is soft, it will collapse and restrict the flow of cooled water from the radiator into the engine and generally slow down the coolant flow. If it's soft, change it for a quality new one, like a Continental, not some store brand (unless maybe NAPA)
• Check your fan clutch and make sure it is working
• Have a good, clean shroud. The shroud is critical to ensuring that the air the fan moves comes through the radiator and does not just circulate around the fan.
• Foam, Foam, Foam - If you look at the diagrams of the radiator mounting in any suppliers catalogs, you will see an ample amount of foam weatherstrip. It's there for a reason and if yours is gone, put it back. This is especially important for the insulation between the hood and the top of the radiator/radiator support. That piece of foam helps to keep the air from going AROUND your radiator. You want THROUGH!
• Ensure that the lower air dam is in place and correct on your car. This should be attached below the inlets on the underside of the front (usually black plastic). If you have the pace car spoiler which became an option in 79, all the better. If you have nothing, you are missing a critical piece that scoops up air and rams it towards the A/C condenser/radiator.

In addition to cooling your motor as efficiently as possible, make the most of your A/C. Lots of people complain that the A/C system in C3s do not have sufficient capacity. I totally disagree with this. It's not a capacity issue, it's an efficiency issue. Here's some things to check on your A/C system that aren't related to freon...

• The HVAC system draws fresh air from the cowl area (through the passenger side down the fenderwell in front of door). Make sure the weatherstrip that seals the front of the cowl against the hood is in good shape. If it's gone or bad, hot air from the engine compartment is being drawn in. It's also a fumes/safety issue so make sure it is a good seal.
• The HVAC system is vacuum powered, so check and make sure that all of the doors are opening and closing as they should. There is a vacuum solenoid that closes the vent door from the cowl. This should close when your A/C is on Max (causes the A/C to recirculate cabin air which could make it cooler). pull the vacuum line from the solenoid and attach a hand vacuum pump to make sure it can hold a vacuum (closes door).
• While you're under there, take a look at all of the plastic vent ducting. There are many pieces and they all have joints which were once sealed by foam insulation, which is most likely all rotted out by now. I know I was cooling the heck out of the dashboard in my car before sealing all of these up.
• Check your firewall for any and all pass-through holes. Clutch pedal linkage is always a good one. Any hole not sealed is letting heat (and fumes) into the interior.

I'm sure there is more and apologize if I am telling you things you already know.

Best of Luck!

 

JOHN HINCKLEY

THERMOSTAT: Probably the most misunderstood component in the cooling system, the thermostat has absolutely nothing to do with controlling maximum engine operating temperature. Period. What does it do? At cold start, it blocks the flow of coolant out of the engine until the trapped coolant reaches the thermostat’s rated temperature, at which point it opens and permits coolant to begin circulating.

Corvette Cooling System

 

Here is another good article as we head into summer.

 

I found the easiest way to explain the thermostat function is to switch the subject to your home. Everyone understand the house system and cooling is cooling. Let's say it is 80 degrees out and you set the AC thermostat to cool the house to 70, and it does it no problem. Then on a 100 degree day with the same 70 setting, house will only drop to 75 degree, not 70. What happened? Well, you added heat load and the system isn't capable to removing all of it. The AC now runs continuously and never shuts off. You wouldn't pull the thermostat off the wall and get a new one would you? Of course not, but when it comes to cars we do it all the time. What you need to do here is get a bigger AC unit or wait until it gets cooler out.

 

You need to go back and read that ENTIRE article again. JH states in his article near exactly what I've been saying all along. I also read another article where he states "No corvette ever left the factory with a cooling problem."

 

I've used a similar analogy with a home heating system a few years back in this forum. People assume a 160* stat will bring the engine temp down to 160* It might if the rad was big enough to begin with but thats doubtful because it wasn't designed to cool an engine down to 160*. I've only read one article by JH on cooling corvettes but I learned heat exchanger design 40 years ago.

 

Resdoggie the bolded part above is the only real point I was trying to make.

 

Same article by JH or its been plagiarized.

Quote from article, "In most cars, it’s (thermostat) essentially wide open all the time (I would differ with that statement and disagree), and only the heat transfer efficiency of the radiator and the airflow through the radiator determine the engine’s maximum operating temperature."

What does "engine’s maximum operating temperature" mean? If the radiator has sufficient capacity i.e. volume of coolant, and is designed to remove hot engine coolant through heat transfer efficiently, then the engine will run at 180*F with a 180*F stat. But if the ambient temperature rises to say 110*F, the rad may no longer be able to reject the heat efficiently because the air passing through is now a lot hotter. So now what will be the engine's maximum temperature? Lets say at 110*F ambient the engine will now run at 220*F. But wait, its in the afternoon now and the ambient is 120*F. Now what's the maximum engine temp? Higher than 220*F! So at some point the engine will run at 180*F as long as the ambient temp has not gone above the original design parameter of the cooling system. I don't know what the GM engineers use for their design parameters which includes the hottest average daytime temperature expected so the engine won't overheat, at least right away - 100? 110? 120? I know when I studied heat exchangers for ocean going ships the maximum design temperature used for seawater was 85*F and a minimum of 30*F. This is based on the two temperature extremes of the water around the world where ship sail. All that said, I can design a radiator that would keep the engine's maximum operating temperature at 180*F no matter where it was driven on the planet. It may not fit well in the current rad opening, lol.

 

If you have the original fan clutch and it's working, keep it. And if you don't keep it, send it to me. I had to change my fan clutch last year (because I'm an idiot and damaged my original, but I digress). After extensive research, I discovered that fan clutches built to original specs are no longer available. In an attempt to consolidate parts, fan clutches nowadays engage at a lower temperature than the original spec fans. The result is they engage the fan more and create a lot more noise. They certainly work well, but the noise from the fan is very annoying.