C5 Cooling System

[Junkman2008]

I respect you but .....you are incorrrect.
With a REAL radiator mine runs 192 (192 t-stat) in 110-115 heat , idling , stop and go , running hard , no matter what the conditions
It never varies more than 1 degree.
The stock radiator is a joke.

Looking at the info I posted from the service manual, your system is running cooler than the original GM design. I can't remember everything that I have read about why the car was designed to run at the temperatures that it does but it was designed that way for a reason. Since I know nothing about designing an engine, I stick to what those who get paid to do so, designed. I can never go wrong following the service manual.

 

[longspur]

So , it seems that anything under 254 degrees is ok.

I remember my 1984 C4 having the same temperature variation characteristics as this current C5.

In comparison my daily drivers rarely wander off the thermostat operating temperature. I guess having a no electric fan keeps things cooler than the Vettes electric fans.

Thanks

 

[c4c5specialist]

HI there,

Ok, lets get to a few points here.

#1, GM strictly states that there should be NO ADDITIVES to be added to any GM cooling system, at all in anyway. You can simply increase the cooling efficiency of the system just by putting 70% water and 30%Dexcool, as water IS the best coolant. It just cannot lubricate water pump seals, prevent freezing below 32F, raise boiling point or prevent corrosion and electrolysis.

#2, stock radiator a joke ???? No, I dont think so. Here is why. This exact stock radiator can withstand full speed validation testing at the desert proving grounds and keeping coolant temps in the operational range. Stop and go at 130F in that area for hours and hours without going out of the operational range. The level of 'cooling efficiency' is subjective to every post here.

#3, People dont want temperature cycling, but why ???? Are they used to older engines that were not able to HANDLE the cyling ????

#4, temperatures in the operational range from cold to 245 are perfectly NORMAL and DOES NOT IN ANYWAY create reliability issues.

#5, if these cars, BONE STOCK WITH NOTHING ELSE ADDED OR CHANGED can run through WEEKS of desert validation testing without an issue, what exactly is the problem ??????

#6, Generation 3 and 4 small block cylinder heads and block run so incredibly cool that running COLDER than the operational range increases carbon buildup and POWER LOSS due to spark knock ignition retard. This is due to maximum octane fuel depositing carbon inside a COOLER engine because it cannot be BURNED OFF!

If you think your radiator has a blockage, you might want to simply try Thexton tool, 467A, which is a wand that flushes water through the radiator or condensor with a 90 degree fan spray. The picture is below.

Personally, inspection and correct diagnostics is critical to evaluating a correct system repair or determination IF there is something wrong.

Allthebest, c4c5

 

[Junkman2008]

HI there,

Ok, lets get to a few points here.

#1, GM strictly states that there should be NO ADDITIVES to be added to any GM cooling system, at all in anyway. You can simply increase the cooling efficiency of the system just by putting 70% water and 30%Dexcool, as water IS the best coolant. It just cannot lubricate water pump seals, prevent freezing below 32F, raise boiling point or prevent corrosion and electrolysis.

That's what I have read per my service manual which makes me leery about putting anything other than what is recommended by GM into my car.

#2, stock radiator a joke ???? No, I dont think so. Here is why. This exact stock radiator can withstand full speed validation testing at the desert proving grounds and keeping coolant temps in the operational range. Stop and go at 130F in that area for hours and hours without going out of the operational range. The level of 'cooling efficiency' is subjective to every post here.

Exactly as I feel. If the car worked perfectly fine when new, why does anything need to be changed if all the parts involved are in working order? I have never seen a thread were anyone bought a new Corvette and then immediately ripped out the cooling system and changed it. For a stock motor, it would have to be adequate or GM wouldn't have mass produced it.

#3, People dont want temperature cycling, but why ???? Are they used to older engines that were not able to HANDLE the cyling ????

And there lies the problem with the mentality of a lot of old school gear heads. Technology with engine design has jumped volumns and the knowledge of those who are not inside the industry has not necessarily moved at the same pace. The same is true with those who want to change their oil every 3 months or 3000 miles in these cars.

#4, temperatures in the operational range from cold to 245 are perfectly NORMAL and DOES NOT IN ANYWAY create reliability issues.

Okay! That's cleared up!

#5, if these cars, BONE STOCK WITH NOTHING ELSE ADDED OR CHANGED can run through WEEKS of desert validation testing without an issue, what exactly is the problem ??????

#6, Generation 3 and 4 small block cylinder heads and block run so incredibly cool that running COLDER than the operational range increases carbon buildup and POWER LOSS due to spark knock ignition retard. This is due to maximum octane fuel depositing carbon inside a COOLER engine because it cannot be BURNED OFF!View attachment 923

If you think your radiator has a blockage, you might want to simply try Thexton tool, 467A, which is a wand that flushes water through the radiator or condensor with a 90 degree fan spray. The picture is below.

Personally, inspection and correct diagnostics is critical to evaluating a correct system repair or determination IF there is something wrong.

Allthebest, c4c5

Thanks Paul. I always look to your advice for clarity.

 

[VETTEX2]

A dual core is a better choice
Why?
you have RESERVE coolling capacity

another reason the stock radiator is a joke is the plastic side tanks

you guys do what you want , you both are A-OK in my book
but
I'll never agree the stock rad is not a joke.

My motors always run where I want them to.
Never cold and never too hot.

I don't want cool temps
I don't want hot temps
192-3 is just fine for aluminum motors
My race motors run 210 all day long.

 

[Hib Halverson]

If I read the OP correctly, the car is an autocrosser run in the stock classes. if that's correct, then mods such as changing the radiator are not allowed. In fact, even a thermostat change may illegal, but it might be pointless, anyway, because, if the car can't cool down to the 'stat opening temp now, putting a lower temp 'stat in won't change that...unless the first thermostat is faulty.

As for coolant additives...I've only used Red Line Water Wetter and in any cooling system where nucleate boiling is present, it will reduce engine coolant temperature (ECT) as much as 20°F. RLWW was the first of these products on the market and, as is the case with any successful product, there are imitators and copies, some of which might be functionally the same and others which might not be.

Back in the early 1990s, I worked with Roy Howell, Red Line Oil's VP and Chemist, to validate for road use the original "Water Wetter" which, when it was introduced, was a race-only product. With the help others and myself, Howell took the first Water Wetter (which came in crystalline form, had to be mixed with water before use and had no anticorrosive properties) to the liquid "pour-in" additive it is today. While Red Line Oil is known mostly as a blender of premium synthetic lubricants, interestingly, it's biggest selling product is Water Wetter.

The "active ingredient" in RLWW and probably some of its competitors is a "wetting agent" which reduces or eliminates the steam bubbles or vapor barrier that forms on the hot metal surfaces in the engine's cooling jackets. Red Line Water Wetter's ability to interfere with the nucleate boiling process can reduce coolant temperatures significantly. When mixed according to the product's directions it can double water's "wetting ability".

It's important to note that Red Line Water Wetter and other coolant additives which have wetting agents as active ingredients will do little to reduce coolant temp unless nucleate boiling is present. When it is present, it usually occurs in the cooling jackets surrounding combustion chambers and exhaust ports in the heads and surrounding the tops of the cylinders in the block. If nucleate boiling is widespread, the coolant temp. reduction will be great. If nucleate boiling is not widespread, the reduction will be less. It follows that the hotter the chambers, exhaust ports and upper cyinders run, the more likely nucleate boiling is to occur. This is why people racing see the biggest reductions in ECTs.

You can get another big reduction in coolant temp by running straight water in the system rather than a mix of Dexcool and water. The current Red Line Water Wetter formula has the extra benefit of having an anticorrosive additive package similar to that in Dexcool and a water pump lubricant. The reason those components are in RLWW is that, besides being intended for use in systems using antifreezes, Water Wetter is also designed for racing use where glycol-based antifreezes are ether undesired or not allowed by racing sanctioning bodies but, once you eliminate the antifreeze, you've lost the corrosion inhibiters and water pump lubricants which are a part of all antifreeze products.

Water is a better coolant than mixes of antifreeze and water. I have been using straight water and Red Line Water Wetter as my coolant on the street and on the track for nearly two decades. There are three rules to observe when using straight water/RLWW coolant.

1) Change coolant every two years regardless of mileage.
2) Don't use it if the car is run hard at altitudes above 5000 ft.
3) Don't use it if the car is parked or stored in ambient temperatures below 32 deg F.

Admittedly, changing coolants before you go to the track is a PIA, but in this instance, as long as you're not autocrossing in the dead of Wisconsin Winter, use of straight water and Red Line Water Wetter for your coolant along with the maintenance procedures discussed here by others should result a noticeable difference.

 

[motorman]

buy a 2 gallon pump up garden sprayer and fill it with ice and water and spray the rad with the fans running between rounds

 

[Junkman2008]

buy a 2 gallon pump up garden sprayer and fill it with ice and water and spray the rad with the fans running between rounds

Are you not worried about that sudden temp change cracking something?

 

[DGVETTE]

Just shoot me!!

I've been reading this (and similiar threads on other forums) about the cooling woes of C5 Vettes during this hot summer and my head is spinning.....:confused

Now this thread explains anthing between cold and 245 is ok.. Fact? If so, not what I want to hear. And yes I am an old school gearhead.

But I don't see this characteristic on ALL new technology engines. My 07 Silverado pickup temp never increases while sitting at a red light. It actually sat with engine idling for 10-15 minutes in the high humidity 99-100 degree day here in the Mid South today with AC running and I didn't see any change in engine temp.

Within minutes of parking the truck I took the 04 Vette for a test drive to compare engine temps. Same streets and same stop lights. Came off the Interstate Highway with a 198 degree engine temp and before I could get through first red light the engine temp was at 208 degrees. Thats a 10 degree increase sitting at a single red light with AC running. I must say the temp never exceeded 215 while in trafic and returned to 198 when I got back to Interstate speed.

I think this is what makes people question the C5 cooling system. I know I don't trust the flipping thing and drive with one eye on engine temp. I also don't know of any other vechicle with such a varying engine temp.

Just my peanut gallery opinion. :W

 

[c4c5specialist]

Hi there,

Your 07 Silverado has a modulated fan setup and is not the low/high speed design of the c5.

That is one of the reason you do NOT see the change, at 200, it runs at 10%.

Allthebest, c4c5

 

[warren s]

My approach to temp control..

I installed a manuall fan switch and a lower temp t-stat.
By switching on either 1 or boths fans, I can maintain coolent temps under 190 on a 90 degree day, and hot lap quester mile passes -or after waiting in the staging lanes.
I did make sure my stock radiator was clean and unabstructed.

No, I usuallly dont run the car when its in the 90s outside, I was at one of the recent Corvette Challenges at Receway Park in NJ and the temps were unexpectedly high.

 

[Tuna]

I used to be part of the 'old school' thinking about coolant tempeartures so when I bought my first C4 with an LT1, it concerned me that I was seeing temps in the 230+ range when stuck in traffic in Houston. I went to the trouble of installing lower temp stats and have chips reprogrammed to turn the fans on sooner. I even installed Big Mouth radiator scopes on my '92 - it really worked at lowering coolant and oil temps. I used Red Line Water Wetter (I still use it).

I got the temps down but I don't think it really mattered to the engine after it was all said and done. Probably spent a lot of time and money trying to second guess the system that didn't need second guessing.

My wife and I do "open road runs" in southwest Texas and there are a lot of Corvettes out there doing the same. We drive the 110 MPH class and, after cruising at that speed for many miles (59 one way), the temps in our cars stabilize arround 215 to 225. Coolant temp has never been an issue. Others that run the faster classes find that oil temperatures are, however, when driving long distances at 130+ and add oil coolers (and trans coolers) to their Vettes. An oil cooler will help lower coolant temps also as oil is part of the engine cooling system.

I still add Water Wetter to all my cars as I think it provides a little extra protection in some conditions. I don't let the coolant temps bother my anymore unless I see something over 240 and that usually means I've got trash in my radiator.

 

[Junkman2008]

I used to be part of the 'old school' thinking about coolant tempeartures so when I bought my first C4 with an LT1, it concerned me that I was seeing temps in the 230+ range when stuck in traffic in Houston. I went to the trouble of installing lower temp stats and have chips reprogrammed to turn the fans on sooner. I even installed Big Mouth radiator scopes on my '92 - it really worked at lowering coolant and oil temps. I used Red Line Water Wetter (I still use it).

I got the temps down but I don't think it really mattered to the engine after it was all said and done. Probably spent a lot of time and money trying to second guess the system that didn't need second guessing.

My wife and I do "open road runs" in southwest Texas and there are a lot of Corvettes out there doing the same. We drive the 110 MPH class and, after cruising at that speed for many miles (59 one way), the temps in our cars stabilize arround 215 to 225. Coolant temp has never been an issue. Others that run the faster classes find that oil temperatures are, however, when driving long distances at 130+ and add oil coolers (and trans coolers) to their Vettes. An oil cooler will help lower coolant temps also as oil is part of the engine cooling system.

I still add Water Wetter to all my cars as I think it provides a little extra protection in some conditions. I don't let the coolant temps bother my anymore unless I see something over 240 and that usually means I've got trash in my radiator.

Good post. One thing that I do see a lot is guys installing lower temp t-stats, thinking that this will lower their overall operating temperatures. This is so far from the truth as the t-stat does not regulate your average temperature, it just sets the point at which coolant starts flowing. I compare it to putting race tires on a 68 Volkswagen Beetle and expecting some kind of major horsepower increase. It's gonna take more than just some tires, just as it will take more than just a t-stat to lower your temps.

For me when it's all said and done, I just won't second guess the GM engineers. They may not be 100% correct on absolutely everything there is, but they have one hell of a track record so far. After all, we are all driving a car that they designed.

 

[VETTEX2]

Good post. One thing that I do see a lot is guys installing lower temp t-stats, thinking that this will lower their overall operating temperatures. This is so far from the truth as the t-stat does not regulate your average temperature, it just sets the point at which coolant starts flowing. I compare it to putting race tires on a 68 Volkswagen Beetle and expecting some kind of major horsepower increase. It's gonna take more than just some tires, just as it will take more than just a t-stat to lower your temps.

For me when it's all said and done, I just won't second guess the GM engineers. They may not be 100% correct on absolutely everything there is, but they have one hell of a track record so far. After all, we are all driving a car that they designed.

The whole t-stat thing always cracks me up.......

Second guess the engineers , they have price , smog and production constraints.
It's not all about performance.
While they did a good job with the constraints they were given , it would be foolish to think improvements could not be made.
I've yet to see a car that could not be improved if price is no object.
Did they give you the best shocks ?
No
Did the give you the best intake?
No
Best Radiator ?
No
Best Brakes ?
No
Best Leather ?
No
Best switchgear ?
No


Did they build a hellava platform to work from?
YES !

 

[Junkman2008]

The whole t-stat thing always cracks me up.......

Second guess the engineers , they have price , smog and production constraints.
It's not all about performance.
While they did a good job with the constraints they were given , it would be foolish to think improvements could not be made.
I've yet to see a car that could not be improved if price is no object.
Did they give you the best shocks ?
No
Did the give you the best intake?
No
Best Radiator ?
No
Best Brakes ?
No
Best Leather ?
No
Best switchgear ?
No


Did they build a hellava platform to work from?
YES !

Now see, you just nailed the whole problem from GM's perspective. Of course we can improve the original design, but can you improve the original design at the same price, following all laws and restrictions that affect your production in every country that the car will be sold in and still please the majority of the masses that will be buying your design?

Of course not. If they made the car using the best parts possible, most of us probably wouldn't be able to afford the car. If we could, we'd be driving a pair of ZR1's or God forbid, an exotic import.

Which I also like by the way...

 

[VETTEX2]

Now see, you just nailed the whole problem from GM's perspective. Of course we can improve the original design, but can you improve the original design at the same price, following all laws and restrictions that affect your production in every country that the car will be sold in and still please the majority of the masses that will be buying your design?

Of course not. If they made the car using the best parts possible, most of us probably wouldn't be able to afford the car. If we could, we'd be driving a pair of ZR1's or God forbid, an exotic import.

Which I also like by the way...

ButI don't care about upgrading parts at the same price.
You stated you wouldn't second guess them.
I do and upgrade accordingly

 

[Junkman2008]

ButI don't care about upgrading parts at the same price.
You stated you wouldn't second guess them.
I do and upgrade accordingly

I don't. Like Clint Eastwood said, "A man's got to know his limitations."

But then, I don't have the same issues that you have.

 

[VETTEX2]

i don't. Like clint eastwood said, "a man's got to know his limitations."

but then, i don't have the same issues that you have. :d

drive it harder !!!!!!!

 

[Junkman2008]

;lol;lol
drive it harder !!!!!!!

Okay! :L