Cooling System Issues

Cooling systems seem simple until you get into BTUs, thermalconductivity, flow, cavitation, pressurization, heat of vaporization,and nucleate boiling. Whatever happened to adding antifreeze and hittingthe road?

Actually, nothing happened to these issues. They're still there, stillin charge of heat transfer in your car, and still the culprits thatcause boil-overs. But you don't have to be a genius in thermodynamics tounderstand the basics of your cooling system and learn some of the stepsyou can take to prevent overheating. While Corvette Fever may be a greatname for a magazine, it's a lousy condition to encounter in the middleof summer.

So here's the Cliff's Notes version of Cooling System 101:
* Engines generate heat.
* Cooling systems dissipate this heat.
* Bigger, more efficient cooling systems dissipate more heat.

Engine heat is a byproduct of combustion. Liquid in cooling systemspicks up heat from passages in the block and heads and carries itthrough a radiator that, obviously, "radiates" the heat into the airpassing through and around the fins and tubes and into the atmosphere.The water pump provides propulsion through the system. Because enginesare most efficient at a particular temperature range, a thermostatregulates the flow of coolant through the radiator to maintain aspecific nominal temperature: 195 degrees F in most Corvettes and otherlate-model cars and light trucks.

We all know that water boils at 212 degrees F. Or does it? Actually, itdoes at atmospheric pressure. However, pressuring a vessel of waterraises its boiling point by roughly 3 degrees for every pound ofpressurization. So in a cooling system running with a 15-psi radiatorcap, pure water won't boil until: (212 + [15x3] = 212 + 45 = 257 deg.F).

Since steam is a terrible conductor of heat, it's far better to keep theold H2O in a liquid state, even at a super-heated temperature.

Factor in the effects of antifreeze, and you can raise the boiling pointof your coolant to something on the north side of 275 degrees F. Butyour engine would be a whole lot happier if you could keep the coolanttemperature down so you wouldn't need all this extra "anti-boiling"protection in the first place.

Parts List

(From Mid America Motorworks catalog)

* High Performance Water Pump, PN 611-131

* Serpentine Belt, PN 611-002

* Fan Switch, PN 609-106

* Low-Temp Conversion Harness, PN 609-108

* Water Wetter, PN 100-891

* 2 gallons of antifreeze

In this article, we'll cover theinstallation of a high-performance water pump, along with a couple ofextra tricks, all courtesy of the good folks at Mid America Motorworks(MAM) who recommend and provided the items discussed here.

The idea of a high-performance water pump is to move the maximum amountof coolant through the engine for picking up all those nasty BTUs andcarrying them through the radiator, which will handle the "radiating"task. The Edelbrock pump recommended by MAM features a larger and moreefficient impeller, as well as a computer-designed pump housing passagesto flow more coolant at a higher velocity, even at lower rpm. Otherfeatures include a heavy-duty ball/roller bearing for extended lifeunder severe operating conditions, a heavy-duty shaft seal, and a uniqueO-ring replacing the conventional gasket sealing the rear impellercover. The chrome-plated housing greatly improves underhood looks.

So how tough is it to change the water pump on a C4? Not too hard ifyou've got 3-4 hours, a standard complement of SAE and metric handtools(see sidebar), and some patience. Here's the deal.