Cooling Issues Solved 327/350

[Rich G.]

Actually, they haven't been all that bad for a few years, but after 14 years of ownership that started with a car on the verge of overheating if it was driven more than five miles, we are today at a place where it runs at 180 degrees all day long in 80-90 degree weather.

The final item is the upper radiator seal available from Doc Rebuild. I THINK this seal is for AC cars but since my car had nothing up there, it made at least a 10 degree difference.

Over the years I have done the following, all because of the knowledge gained here:

DeWitts Radiator ( BIG HELP). The car had a copper radiator when I bought it and it was in bad shape

Proper Vacuum can and timing (per Duke's two inch rule) Thanks Duke!

New fan clutch from J&R

Upper radiator seal. Surprised at the difference this made.

After I installed the radiator the car was drivable but I had to avoid traffic jams on hot days. All the other changes made incremental but noticeable improvements.

So, I guess the moral of the story is, if you make it like The General did when it was new, it should work like it did when it was new.


Thanks for all the tips over the years

Rich

[Mark E.]

Re: Cooling Issues Solved 327/350

Thanks Rich; that's good information to share.

The cumulative effect of all your changes reminds me that it's a cooling SYSTEM, and for a system to work properly all its individual elements must work properly.

[Joe L.]

Re: Cooling Issues Solved 327/350

Actually, they haven't been all that bad for a few years, but after 14 years of ownership that started with a car on the verge of overheating if it was driven more than five miles, we are today at a place where it runs at 180 degrees all day long in 80-90 degree weather.

The final item is the upper radiator seal available from Doc Rebuild. I THINK this seal is for AC cars but since my car had nothing up there, it made at least a 10 degree difference.

Over the years I have done the following, all because of the knowledge gained here:

DeWitts Radiator ( BIG HELP). The car had a copper radiator when I bought it and it was in bad shape

Proper Vacuum can and timing (per Duke's two inch rule) Thanks Duke!

New fan clutch from J&R

Upper radiator seal. Surprised at the difference this made.

After I installed the radiator the car was drivable but I had to avoid traffic jams on hot days. All the other changes made incremental but noticeable improvements.

So, I guess the moral of the story is, if you make it like The General did when it was new, it should work like it did when it was new.


Thanks for all the tips over the years

Rich

Rich-------

The installation of seals to the radiator and shroud, including the addition of seals which GM may not have used as part of the original installation for a particular application, can make a very large difference in cooling, especially at low speeds. Sometimes, the addition of seals or the use of improved seals can make a car "incorrect". If one intends to drive the car, so be it.

[Rich G.]

Re: Cooling Issues Solved 327/350

Joe

My car is a lot more than one radiator seal away from judging

I like to drive and I like it more when everything works the way it should, even though it may not look the way it should.

I've said before I have the utmost respect for those who keep or restore their cars to judging standards. It's a lot of work and requires more dedication and stamina than I have. It's a great hobby. Something for everybody.

Rich

[Duke W.]

Re: Cooling Issues Solved 327/350

So, I guess the moral of the story is, if you make it like The General did when it was new, it should work like it did when it was new.

Rich

That's the real deal!

GM knew that a big engine in a small car would require better than average cooling system components. The clutch fan and especially the stacked plate furnace- brazed aluminum radiator that has about 30 percent higher heat transfer rate than a copper radiator of the same size were necessary to ensure proper cooling. That was a very "high-tech" component for the day, and GM didn't spare any expense to build a highly functional and reliable cooling system.

As the cars got older and various components degraded a lot of guys tried amateur solutions like snake oil additives to the coolant, "high-flow" water pumps, and electric fans, and they rarely helped.

It's always been my position that if you restore the cooling system components to original as-new performance, cooling will not be an issue. The 600 pound gorilla is the aluminum radiator, which is not cheap, but a must if you want to ensure a properly functioning cooling system, and we are fortunate that the excellent DeWitts OE equivalent aluminum radiator is available.

Anecdotal evidence over the decades suggests that, with proper maintenance like coolant changes at least every five years with a 50/50 blend of HOAT antifreeze like Zerex G-05 and distilled water, the aluminum radiator will likely provide at least 40-50 years service.

Verify that the radiator is electrically isolated from the chassis so as to not form a galvanic cell that will sacrifice aluminum over iron, so be sure those mounting grommets are in good shape and use a ohmmeter to verify that the radiator is electrically isolated from the chassis.

It's also important to understand that 180 degrees is the minimum warmed up operating temperature. Higher operating temperatures in tough conditions like freeway jam-ups in hot weather are perfectly normal. I consider the normal operating temperature range to be 180-230, and with a 50/50 G05/distilled water blend, and a 15 psi cap that actually holds 15 psi the boilover temperature is 265F.

On modern cars that usually also have 15 psi caps the fans usually don't engage until 220-230 with the AC system off. When the AC system is on the engine may actually run a little cooler due to the fan(s) engaging based on the condensing needs of the AC system.

Duke

[Mark E.]

Re: Cooling Issues Solved 327/350

It's also important to understand that 180 degrees is the minimum warmed up operating temperature. Higher operating temperatures in tough conditions like freeway jam-ups in hot weather are perfectly normal. I consider the normal operating temperature range to be 180-230, and with a 50/50 G05/distilled water blend, and a 15 psi cap that actually holds 15 psi the boilover temperature is 265F. Duke

Thanks you Duke.

So running 230 degrees shouldn't be a concern in our vintage cars? I understand this is below boil with the proper coolant mix and pressure cap, but doesn't that temperature put extra stress on components? I get nervous when the needle goes past the center of the gauge.

[Duke W.]

Re: Cooling Issues Solved 327/350

230 is the maximum temperature I would be comfortable with in extreme conditions. Elastomeric materials like radiator, and fuel hoses degrade faster at elevated temperatures, so their life can be shortened, but how much time do you spend in a vintage Corvette in extreme conditions?

Modern hose materials are much better and longer lived than back in the day, but I can only say that about hoses that you buy from major manufacturers than meet current industry standards. I don't know about "reproduction" hoses that are cosmetically correct or near correct. Who knows if they are made from the latest spec materials.

Few modern cars have calibrated temperature gages, but you can be sure than in extreme conditions they often run in the 220-230 range, and if you live in a hot climate and have a long, slogging commute that could be virtually every day from Spring to Fall.

Also consider that cast iron block/head engines are quite forgiving of continued operation after loss of coolant due to boilover... a lot more so than modern aluminum head and/or block engines. It's doesn't take much to warp aluminum engine components, so it's best to shut down any engine ASAP when boilover occurs to prevent damage.

In 1990 the '89 Saleen Mustang I drove in the Silver State Classic Challenge ran up to about 220 during the race (I removed the clutch fan to get rid of that parasitic loss and taped up a good portion of the grille to reduce aero drag.) We had one mile to stop the car after I crossed the finish line at about 160 MPH, and I quickly found a parking spot beyond the shut down area knowing that the engine was very hot.

About a minute after shutdown the residual heat in the engine caused coolant boilover, and it was so intense that coolant was expelled from the overflow tank. This went on for several minutes and it probably ejected a couple of quarts of fluid, but since we had time to hang out before heading back to Vegas I just let it sit for a couple of hours then rounded up enough water to fill up the cooling system. Of course that 302 HO engine was all iron and showed no ill-effects though the owner (my navigator) sold the car about a year later, so I don't know its ultimate fate.

The year prior when I entered my '88 MBZ 190E 2.6 I didn't remove either the mechanical viscous clutch fan or auxiliary electric fans due to the difficulty in doing so, but I did tape up about half the grille opening. On a long uphill straight it got up to about 100C where the clutch fan tighened, and that cost me a few MPH on that stretch, but the temperature dropped below 100C after the road flattened out and for the rest of the race, and it didn't boil over after I parked it and shut down the engine.

My biggest competition was a gray-market 190E 2.3 16V. He started a few cars behind me, and about a third of the way through the 92-mile race on Nevada state route 318 I saw him closing on me about a quarter mile back, then he disappeared. After the race he told me that the head gasket let go, and he had to pull over, so I won the sedan, under 3-liter class.

Both his 2.3L DOHC four-valve inline four and my 2.6L inline six are cast iron blocks with a aluminum heads, which is the worst combination for head gasket longevity due to aluminum's three-times higher thermal expansion rate than iron.

Just short of the expiration of my 2.6's 4-year/50K warranty the head gasket started to seep on the exhaust side, and it was replaced on warranty. They also completely refreshed the head with all new guides, new exhaust valves, and a later valve seal design with upgraded material (Viton), and took a small surface cut to ensure the mating surface was flat. Now after nearly 25 years, but only another 35K relatively easy miles I'm sure the engine will last longer than me without need for major repair.

I had a great relationship with my Mercedes dealer service department.

Duke

[Mark E.]

Re: Cooling Issues Solved 327/350

Just short of the expiration of my 2.6's 4-year/50K warranty the head gasket started to seep on the exhaust side, and it was replaced on warranty. They also completely refreshed the head with all new guides, new exhaust valves, and a later valve seal design with upgraded material (Viton), and took a small surface cut to ensure the mating surface was flat. Now after nearly 25 years, but only another 35K relatively easy miles I'm sure the engine will last longer than me without need for major repair.

I had a great relationship with my Mercedes dealer service department.

Duke

Great story Duke. Your relationship with the dealer must be good since they covered repairs under warranty to a car used in competition.

[Gene M.]

Re: Cooling Issues Solved 327/350

In a reply to this thread Duke stated: "Verify that the radiator is electrically isolated from the chassis so as to not form a galvanic cell that will sacrifice aluminum over iron, so be sure those mounting grommets are in good shape and use a ohmmeter to verify that the radiator is electrically isolated from the chassis."

My question is should the aluminum radiator "float as isolated" so the aluminum is saved from acting as a sacrificial anode? Would that just be at the points where the aluminum is mounted to ground at the core support if no rubber isolation is used?

[Duke W.]

Re: Cooling Issues Solved 327/350

I don't understand your question, but any basic chemistry book will have a section on galvanic cells, or you can just look it up on the web... two electrically connected dissimilar metals immersed in an electrolyte. It's essentially a battery and a voltage is generated.

Then look at the positions of the two metals on the EMF table to see which one will be sacrificed.

Despite corrosion inhibitors, a proper blend of antifreeze and water is still a weak electrolyte, and both aluminum (radiator) and iron (block/head) are immersed in it, and if the aluminum and iron are electrically connected you have an aluminum-iron galvanic cell, and aluminum is the sacrificial material.

Break that electrical connection by electrically isolating the aluminum radiator from the chassis/engine ground plane, and you no longer have a galvanic cell.

My ...316 radiator developed pin hole leaks after only about 12 years of service despite antifreeze changes every two years. I always knew the top of the radiator had some fore/aft movement, but it wasn't until I bought a AIM that I realized that the rubber grommet was never installed, so my aluminum radiator was electrically connected to the iron engine and galvanic action destroyed it in a relatively short period of time despite rigorous maintenance.

The radiator has two bottom mounts and one top mount, plus the hoses. Of course the rubber radiator hoses are not conductive, and the rubber grommets on the mounts provide some mechanical shock isolation, but electrical isolation from the chassis is even more important for long service life.

If you check for continuity between a properly installed radiator (any radiator regardless of material) and any point on the engine/chassis ground plane or negative battery post, it should be infinite.

Duke

[Joe L.]

Re: Cooling Issues Solved 327/350

If you check for continuity between a properly installed radiator (any radiator regardless of material) and any point on the engine/chassis ground plane or negative battery post, it should be infinite.

Duke

Duke------


The RESISTANCE should be infinite.

[Terry M.]

Re: Cooling Issues Solved 327/350

I don't understand your question, but any basic chemistry book will have a section on galvanic cells, or you can just look it up on the web... two electrically connected dissimilar metals immersed in an electrolyte. It's essentially a battery and a voltage is generated.

Then look at the positions of the two metals on the EMF table to see which one will be sacrificed.

Despite corrosion inhibitors, a proper blend of antifreeze and water is still a weak electrolyte, and both aluminum (radiator) and iron (block/head) are immersed in it, and if the aluminum and iron are electrically connected you have an aluminum-iron galvanic cell, and aluminum is the sacrificial material.

Break that electrical connection by electrically isolating the aluminum radiator from the chassis/engine ground plane, and you no longer have a galvanic cell.

My ...316 radiator developed pin hole leaks after only about 12 years of service despite antifreeze changes every two years. I always knew the top of the radiator had some fore/aft movement, but it wasn't until I bought a AIM that I realized that the rubber grommet was never installed, so my aluminum radiator was electrically connected to the iron engine and galvanic action destroyed it in a relatively short period of time despite rigorous maintenance.

The radiator has two bottom mounts and one top mount, plus the hoses. Of course the rubber radiator hoses are not conductive, and the rubber grommets on the mounts provide some mechanical shock isolation, but electrical isolation from the chassis is even more important for long service life.

If you check for continuity between a properly installed radiator (any radiator regardless of material) and any point on the engine/chassis ground plane or negative battery post, it should be infinite.

Duke

I just attended a C6 maintenance seminar at the NCM, and the presenter recommended the coolant used in Chevrolet Volts. He stated it was formulated to withstand some high voltage, I think he said, around 500 volts and is produced with deionized water. I may have written the part number in my notes, but I am just off the road and have other priorities at the moment. I just thought I would throw that out there while we were on the subject. If there is continued interest, there is a longer story for later.

[Leif A.]

Re: Cooling Issues Solved 327/350

I just attended a C6 maintenance seminar at the NCM, and the presenter recommended the coolant used in Chevrolet Volts. He stated it was formulated to withstand some high voltage, I think he said, around 500 volts and is produced with deionized water. I may have written the part number in my notes, but I am just off the road and have other priorities at the moment. I just thought I would throw that out there while we were on the subject. If there is continued interest, there is a longer story for later.

To Terry's point:

[Duke W.]

Re: Cooling Issues Solved 327/350

High voltage protection is not necessary for vintage Corvettes or any non-hybird vehicle. Also, the Dexcool formulation and other OAT technology antifreezes do not provide optimum corrosion protection for solder. An HOAT formulation like Zerex G-05 is best for cars with soldered components. Even if your vintage Corvette has an aluminum radiator, it still had a soldered brass heater core.

Duke

[Duke W.]

Re: Cooling Issues Solved 327/350

Duke------


The RESISTANCE should be infinite.

Thanks for pointing out and correcting my poorly worded statement.

Duke