Overheating... SBC 350

[chevurai]

Never mind reading up on radiator heat transfer theory...just read the last couple of replies from fieldsken1 All of it is good stuff.
The comment about checking the radiator hoses for collapse is a good one. Its hard to detect in a shop setting and may make the overheating issue seem random. I had a car that ran fine most of the time but when more was demanded from the engine it overheated. To make a long story short, on one demanding uphill climb it over heated and coolent came out of the overflow tank. When the coolent heated it burped into the tank and when the engine cooled down the lower hose collapsed flat and did not draw the coolent back into the radiator. Eventually the coolent was replaced with air...not good. I just hapened to pop the hood and catch the hose in a collapsed condition. The fix was to make a coiled wire out of a stainless steel welding rod that was in the shop and insert it into the hose. No more over heating issues. Maby it's just me but it seems like hoses these days are more pliable and the hose with the bend that you need is not available with an internal spring.

 

[jackbrad]

Here are a few pics of the front.

 

[jackbrad]

 

[Gumby]

Wow. I've seen some s***ty advice on this forum before. Using straight water might be the worst yet.

Please, verify anything you read on Internet forums. Any idiot can post on them and they usually do.

 

[fieldsken1]

Wow. I've seen some ****ty advice on this forum before. Using straight water might be the worst yet.

Please, verify anything you read on Internet forums. Any idiot can post on them and they usually do.

whats wrong with water??? been using it in race cars for years and it works fine. for the winston west and nascar and the late models they only allow water. they dont want coolant on the track. if you read the whole paragraph it says coolant can be used for other reasons.

 

[fieldsken1]

Water is used in the cooling system because it can absorb a lot of heat energy, then carry it away to the radiator. Now as the water temp rises, the water would normally transform into a gas phase at about 100 degrees celcius. But the system is kept under pressure, and by obeying physics laws, the pressure prevents expansion and forces the gaseous molecules to stay in a liquid phase. The basic equation is P*V=n*R*T.
The specific heat capacity of ethylene glycol-based water solutions is less than the specific heat capacity of pure water. In a 50 percent solution, ethylene glycol's specific heat capacity compared with pure water is decreased at least 20 percent at 36 degrees F, and about 17 percent at 200 degrees F. Propylene glycol, another common coolant, has an even lower specific heat. Compensating for the reduced heat capacity of coolant/water mixes would require circulating more fluid through the system, but assuming a fixed amount of circulating fluid and radiator capacity, this makes water the most efficient coolant in terms of its ability to conduct heat with minimal temperature rise. In other words, of all common liquids, water requires the most heat energy to changes its temperature.

Looking at some concrete numbers, according to cooling system guru Howard Stewart, on a typical engine with a coolant flow rate of 100 gpm (gallons per minute) and an energy loss through the coolant system of 189.5 HP , the water temperature increase would be 10 degrees F, the ethylene glycol water mix would gain 20 degrees, and the propylene glycol would gain 33.3 degrees F.

Admittedly, this is the relationship in its pure form that does not account for differences in the vapor point of the three different coolants. Ethylene glycol and propylene glycol have higher vapor points and therefore can absorb heat at higher temperatures without boiling. However, even with its lower vapor point, water still carries more heat per unit than the other coolants.

Also remember you cannot look at just water in isolation. It's just one part of the total cooling system. You can raise water's effective vapor point by using a higher pressure radiator cap. For every point of system pressure increase, the boiling point of water will increase by 3 degrees F. A higher boiling point also helps reduce evaporation losses, water pump cavitation, and heat-soak-induced-after-boil. You can get away with a higher system pressure by using a quality aluminum radiator that's much stronger than an old-school brass/copper radiator, making that aluminum unit a dual pass configuration to speed up coolant flow enhances heat transfer even more.


In short, a dual-pass aluminum radiator with at least a 20 psi cap running only water is by far the best heat transfer setup, provided the vehicle is not subject to freezing conditions. Be sure to add a corrosion inhibitor to protect the system.

 

[reddingcruiser]

And there will be an exam tomorrow for all those in Professor fieldsken's class - so study!

 

[DSRTRDR]

 

[Gumby]

whats wrong with water??? been using it in race cars for years and it works fine. for the winston west and nascar and the late models they only allow water. they dont want coolant on the track. if you read the whole paragraph it says coolant can be used for other reasons.

He's not driving a race car, dumbass. He's not going to drain his coolant after every race and replace his engine many times during a year. Nor is he likely to store his vehicle in a climate controlled space.

Water will freeze at 32f. Maybe it never, ever gets that cold where he's at, but chances are pretty good it will at some point in Charlotte NC. All it takes is once.

Water boils at well below normal engine temps and well below ethyl glycol. Why would you diminish your boiling protection. Even if the overall system temp is below boiling temps given a pressurized system, water will boil in localized hot spots causing poor cooling, steam erosion and cavitation issues. The steam erosion and cavitation scours the parts of corrosion protection, as well as destroys parts, particularly aluminum and water pump impellers.

Water corrodes. You can buy anti-corrosion additives, but running the proper mix of coolant coats your parts with anti-corrosive protection. It's easy to have the proper amount, easy to check, and easy to renew.

Water is a horrible lubricant. Coolant provides water pump protection that water does not.

Water does have a better heat absorption rate. That's why you don't run 100% coolant. 50/50 mix is close enough to water as to not make a difference.

You run a 20 psi cap on a stock system and you'll have problems. The rest of the system is not designed for it. Not even with fake braided hoses.

You can cut and paste long ass articles all you want, it's not going to diminish the fact that you are giving horrible advice that somebody might actually follow because they don't know any better. You feel free to do whatever you want.


Bottom line is the OP needs to get his system working properly, not do dumb s*** like run water, special t-stats and a 20# cap.

 

[fieldsken1]

i am not giving horrible advice all i said was water has a better heat absorption rate just like you agree. i never said to use 100% water so read it again dumbass. yes you need coolant because of the additives. i never said you dont dumbass.

 

[Gumby]

Nice backpedal. Did you read your cut and paste articles?

For the OP.

There is good tech in this thread mixed in with the ravings of morons.

A four core radiator is helpful, but not always a panacea.
An aluminum radiator is better and can be had for sometimes less money.
A good mechanical fan with a very good shroud is important or a very good electrical fan with a good shroud.
The bypass idea for the vortec is a good one I will try. My SWB got pretty hot in high ambient temps while wheeling. That does bring out cooling shortcomings, probably more so than trailering to the church car show.
I would always recommend a high quality, fail safe thermostat of the proper heat range (not cooler) with a jiggle valve.
Make sure the cap is in good working order and is of the proper pressure for your system. Caps are very often overlooked. Run a two way cap even if your rig is old enough to not have a overflow, because...
run an overflow. It keeps the radiator full and at the proper level all the time and keeps antifreeze out from under my motorcycle tires.
Check the rig is running properly. Running lean will make the engine run a lot hotter and eventually hurt the motor. Low tire air pressure will help with traction off road and help the ride on an old leaf sprung rig considerably, but it will make the motor work a lot harder, especially at highway speeds.
Run the proper mix of the correct coolant. Running too much coolant to water will not help. As has been posted 50/50 mix will remove heat better.
It might just be that running a brick down the highway at modern speeds with the AC on and a winch in the way is going to be difficult.

 

[reddingcruiser]

I've said it before on these overheating issues: the closer your cooling system resembles the design that the GM boys conjured up for a particular application (i.e. coolant type and capacity, air flow, heat exchange rate, pump GPM output, yadda, yadda, yadda), the fewer problems you'll have.

 

[LandCruiserPhil]

Water Wetter used as an additive meets the 100% water concerns and IIRC is track approved.

Technically the water molecule is not corrosive the impurities in water is the corrosive.

With all the talk about coolant I'm still betting the cooling issue the OP is experiencing air flow related.

Multiple engine water outlets into a swirl pot will eliminate any engine heat issues but again without proper radiator air flow the problem will persist.

 

[fieldsken1]

its a thermostat. he needs a high flow thermo.

 

[fieldsken1]

maybe he will tell what the fix is so we all know

 

[fieldsken1]

Nice backpedal. Did you read your cut and paste articles?

yeah i read the articles and i still dont see where it says use straight water only. it does say you need to use additives for lubrication and corrosion.

 

[caladin]

It's been a bit but I did some quick math and 50/50 water antifreeze, with water wetter added is almost as efficient at heat transfer as pure water... so that's the route i went for a little boost on that end, not being "brave" enough to run pure water her e in Texas, i had a car freeze up and crack the block once.. not fun...

 

[Brian in Oregon]

The reason an aluminum radiator conducts heat better than a brass/copper radiator is not because of the material it is made out of, but because of the assembly method. Aluminum is actually less efficient at conducting heat (49%) than brass or copper (the latter being 92%). The problem with brass or copper is due to the use of lead based solder to bond the fins to the tubes.

Even so, an aluminum radiator that copies 1960s technology is not going to be significantly more efficient than a brass/copper radiator. It's main advantage is weight reduction, weighing about 2/3 to 3/4 less.

A bigger difference can be made by going to 3/8" tube spacing instead of 1/2" tube spacing. This is pretty much what the Japanese did in the 1970s with their small vehicles. They were able to cram in more cooling in a smaller radiator than a larger one because of more tubes.

My aluminum 4-core radiator has 1/2" tube spacing, and I doubt it is significantly better than the brass/copper version.

And as far as Ken's remark about water, he's right that water cools the best. I dunno if the caveat was stated or not that it needs anti-corrosion and anti-freezing additives, and I'm not going to go back and sift though looking for it, but I would assume most people on this site know that.

The real point is that if cooling is an issue on a vehicle, it's best to add ONLY as much glycol as needed to protect against freezing. If your area only drops to 20 degrees, don't protect it to -20 degrees. It's a waste of coolant, which ain't getting cheaper, and it will lower the efficiency of the cooling system.

 

[jackbrad]

Thanks for all the posts here guys. Its good to see you guys caring enough to help me despite differenting comments. Right now, I plan to employ all the tips on here that seem reasonable. (And there are many). As was stated, "It might just be that running a brick down the highway at modern speeds with the AC on and a winch in the way is going to be difficult. "

I will post back to you guys as soon as I get some parts in to try some stuff.

Jack

 

[Gumby]

I wanted to post up that I did the bypass hose on my vortec heads and it seems to have made a difference. I did a bunch of research when I put the heads on and read many many posts about they were bolt up and no mods needed other than a manifold.

I've since found the bypass hole thing and found the water pump is not as long as a non-serp, non-votec long pump and is needed if you run the serp belt system with the vortec heads.

I do run a ball valve in my heater hose so that may make a difference too, although both heater hoses come off the water pump.