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7.3L Power Stroke Cooling System Upgrades

Ford Fixes

Mike McGlothlin
Jun 1, 2010
Photographers: Mike McGlothlin
The latest installment of our '97 Ford F-350 project entailed tackling another preventative maintenance issue: replacing the factory, 145,000-mile water pump. It's anyone's guess how long a 7.3L's stock water pump will last, as we've seen some fail with little more than 100,000 miles on them, and some that have lasted beyond 200,000 miles. More often than not, a damaged coolant system leads to this vital component failing. Things like cooling system contamination, bearing overload, an unbalanced fan clutch, insufficient clearance between the fan and fan shroud (or radiator), and engine overheating can all contribute to a failed water pump. Being proactive, we decided to replace our 7.3L Power Stroke's factory unit with a brand-new water pump from Bosch. This is a weekend project anyone can handle and only required a few special tools to get the job done.
Photo 2/12   |   Bosch's water pump for the 7.3L Power Stroke is brand-new (PN 99170) and came with all the necessary gaskets, O-rings, and even a new water neck outlet. It can be had for just $140.95 from Auto Anything. In addition, we opted to use DieselSite's 203-degree thermostat during the install, and it also supplied us with an OE water neck inlet and one of its coolant filtration systems.
For added performance and insurance, we also installed a 203-degree thermostat and coolant filtration system from DieselSite. With the truck now running at its ideal operating temperature and the engine benefiting from uncontaminated coolant, our water pump's life will be prolonged considerably, and our cooling system should be problem free for years to come.
Photo 3/12   |   We got started by draining all of our Power Stroke's coolant into a 5-gallon bucket and an empty cooler. Then we removed every radiator hose, the four bolts securing the water pump pulley were loosened using a 10mm socket, and the serpentine belt was pulled.
Why Water Pumps Fail:
The photo shown below is of an '01 7.3L Power Stroke engine's failed water pump with just 127,000 miles on it. Notice the odd angle of the pulley? This is because the bearing assembly in the water pump failed. Typically, the seal will fail first, in which you'll notice a slight coolant leak, or drip. Obviously, this was not the case here, and there were no warning signs that the pump was on its way out. The truck owner was lucky the failed bearing assembly didn't damage the front engine cover, fan clutch, or even the radiator. The seven main causes of water pump failure are:
Cooling system contamination
Overheated cooling system
Bearing overload
Excessive fan belt tension
Insufficient clearance between the fan and shroud, or radiator
Unbalanced fan clutch
Excessive vibration due to loose (or broken) motor mounts
Photo 4/12   |   diesel Power 1997 Ford F350 Cooling System failed Pump


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