Water Pump

When it comes to improving the performance output of any car – be it a classic or late-model – the cooling system is typically, the most forgotten and neglected part of any build. We’re all guilty of making the cooling system an afterthought, and at some point, it usually comes back to bite us. That’s because we’re all power junkies and want to build tire-buckling power, and the cooling system is one aspect that doesn’t get as much forethought as it should. That is, unless you’re the guys at Tuff Stuff Performance.

Water pump

Inside is a non-corroding, low cavitation impeller that reportedly increases water flow by 30-percent to drop coolant temperatures by up to 20 degrees.

If you’ve been checking out Chevy Hardcore for any length of time, you’ve undoubtedly seen the ’79 C10 I’ve been upgrading. The Cheyenne is our daily driver and “project,” and the upgrades are really making this an even better truck than it was from the factory. But one thing I have noticed when driving on the Interstate at highway speed (70-75 mph) in the sweltering Florida heat with the air conditioning on, the engine temperature would eventually creep up to the “warmer than I like it to” area. Basically, the temperature would climb to between 198-205 degrees. That is not a dangerous level, but it’s getting close, and I wanted to take care of it.

water pump

Although not extremely hot, the temperature would fluctuate between 198 and 205 degrees in traffic. I was curious to see if changing only the water pump would have an affect.

Deductive Reduction

I knew that if the ignition timing was off or the carburetor was too lean, these conditions could create the issue, so I started by checking in those areas. Once I was confident that timing and fuel squirting were what they should be, I started to do a little research. I found that Tuff Stuff has a water pump that they claim will drop engine temperatures up to 20 degrees. I was certain that – in this situation – a thermostat swap probably would not lower the engine temperature – I’ll explain later. Since the fan was pulling a sufficient amount of air through the radiator, that led us to think the water pump might need an upgrade. Since it was coated with a layer of brown seasoning and not a hint of paint, I felt it had been replaced at one time and was not factory installed. Not knowing when it had actually been replaced, but knowing that it would eventually need changed, I was game to try the new water pump.

Dropping engine temps 20 degrees just by changing a water pump sounded a little far-fetched to me, but Mike Stasko of Tuff Stuff explained what they have done to their water pump design to enables this to happen. “Tuff Stuff’s SuperCool water pumps feature a steel, fabricated water pump impeller rather than an OE-style, cast-iron impeller.” Additionally, most of our SuperCool water pumps feature an aluminum casting, which also helps to dissipate heat,” he said.

water pump

Since there was no paint remaining on the water pump, I deduced that it had been replaced at some time. But when, is anyone’s guess.

By modifying the impeller, Tuff Stuff says they have created a low-cavitation impeller that actually increases water flow by 30-percent. But, is increasing flow that important? Look at it this way, a car’s cooling system is designed to absorb engine heat. The coolant needs to flow properly to absorb and then dissipate that heat. But, there are areas in the engine’s cooling system where water flow tends to slow because of the design and subsequent restriction of the passages available for the water to flow.

Accurate Measuring

water pump (3)To attain our readings, I used an infrared gun while the truck was at idle, but that wasn’t an option at speed. Several months ago, I installed a set of Dakota Digital HDX gauges in my C10, which I was certain were more accurate than the 38-year-old factory pieces. I confirmed this by comparing the truck’s new HDX temperature gauge to my infrared gun reading while at idle, and they were consistently within a degree of each other.

These restrictions, and the fact that heat is developed in varying degrees within an engine, mean the temperature absorbed by the coolant is not uniform throughout the entire cooling system. Your engine will have hot spots, and the variations in temperature can cause the flow of the coolant to vary in different areas. Controlling the temperature variations or extremes within the system is important. Hence, the need for adequate flow. It used to be thought that the amount of time the coolant spent in a radiator equaled the cooling capability. In other words, if you keep it in the radiator longer, it should cool better. But, is that really the case?

How many times have you heard that removing a thermostat will cause your engine to overheat because the coolant didn’t stay in the radiator long enough? We asked Bud Riser, Tuff Stuff’s resident tech guy about this, and he concurs. So, in order for a cooling system to work properly, a balance needs to be reached. That is why a controlled but continuous coolant flow is so important.

Digging In

With that information in hand, I ordered one of Tuff Stuff’s water pumps and decided to conduct a very unscientific test. Even though I had no PhD-laden group of scientists helping, I knew I needed to quantify my results. Before the old system was altered in any way, I began by starting the truck and letting it idle in the driveway for 15 minutes. I chose that amount of time, because when that point was reached, the temperature seemed to neither increase or decrease. At the end of that time, the engine temperature was a comfortable 185 degrees. That means the thermostat is functioning as it should. I already know and mentioned the cruising temperature, so I began the swap.

water pump

The new water pump comes with the heater hose connection, but since the C10’s is in a different location. I swapped it for a plug.

Usually, changing a water pump is a simple endeavor. But, the C10 has air-conditioning and power steering, and the requisite brackets and extra belts did cause me to occasionally comment about their presence in this application.

Now, I’m not going to get into the details about how to change a water pump – that’s easy. Rather, I’ll just get into the real matter at hand; did it change the range at which the temperature gauge moves while driving. I previously mentioned that the truck held a consistent 185 degrees after fifteen minutes of idling and then retained that temperature. The real test would come while driving down the Interstate at speed.

It is probably best to point out that the only thing I changed was the water pump. Even the antifreeze used before the swap was put back in service, and the outside temperature and humidity was 91 degrees with 72-percent humidity before the swap, and 93 degrees with 73-percent humidity after the swap. Welcome to Florida, the land of two seasons: Summer, and get me the hell outta here! Trying to keep all things equal, I also drove the truck on the same route as was driven before the swap, and took readings at the same speed and engine RPM.

water pump

Tuff Stuff says that up to a 20-degree reduction in temperature is possible. I was happy seeing 10 degrees less heat generated.

Did It Fix The Problem?

To say that I was surprised is an understatement. The pre-drive idle did not notice any change, and the temperature held true at comfortable 185-degrees. Again, the thermostat is working. With the engine at operating temperature, I proceeded to drive the same route I did before the swap. This time, however, the temperature did not reach the previously-obtained 199 degrees. During this trip, the temperature only climbed to 188 degrees. While not the total, possible 20-degree drop that Tuff Stuff says is possible, The engine did see an 11-degree reduction in temperature, which in the Florida summer is outstanding in my book.