Replacing the water pump is a last-resort repair to salvage your truck's coolant system. To replace the water pump, located above the crankshaft, you must work your way through many parts. The water pump is responsible for applying enough force to circulate the water through all the necessary components to keep your truck running smoother and cooler. Here's how to remove and install a water pump on your 1985 Chevrolet S-10.
Tools Used: Large tub, Pliers, Socket set, Flat-head screwdriver, Putty knife, New water pump, New gasket, RTV silicone, Pry bar, 2 gallons antifreeze, 2 gallons water
Install Water Pump
Removal of the Water Pump
Open the hood of the truck. Locate the water pump; it's in the front of the motor along the path of the belts.
Remove the belt off the pulley by loosening the alternator bracket with the socket wrench. The alternator will slide loose, and the belt will come off.
Place the tub underneath the radiator. Find the petcock valve along the bottom of the radiator. Turn the valve counterclockwise with the pliers to release all the water from the radiator.
Remove the fan shroud by using the socket wrench to pull out the two bolts at the top corners of the fan shroud and two more bolts along each side.
Take out the fan by loosening the bolts in the fan clutch, using the socket wrench. There will be three to four bolts holding the fan in.
Remove the radiator hose at the bottom of the water pump. Do this by loosening the hose clamp with the flat-head screwdriver; the hose will slide off the hose inlet pipe.
Use the socket wrench to loosen the bolts on the water pump. There will be as many as 10 bolts to remove from the water pump housing. Then simply slide the water pump off.
Clean the surfaces where the water pump was mounted, using something with a sharp surface, like a putty knife. The idea is to remove the old gasket material from the surface of the motor where the replacement pump will mount.
Installing the Water Pump
Place the new gasket on the mounting surface of your new water pump. You will notice a grooved area where the gasket will sit. You can put the gasket on dry, or use RTV silicone to ensure the gasket sticks to the water pump.
Extract the pulley from the old water pump using the socket wrench to take out the bolts. Attach the pulley to the new water pump if it did not come with one.
Assemble the water pump back onto the motor, tightening all the bolts with the socket wrench. Ensure that this pump matches up exactly like the old one did.
Place the radiator hose back on the inlet pipe. Tighten the hose clamp, using the flat-head screwdriver, until the hose is snug.
Place the fan back on the fan clutch. Tighten the bolts to hold the fan to the clutch. Then mount the fan shroud back around the radiator, tightening the bolts with the socket wrench.
Finishing the Installation
Close the petcock valve on the radiator by turning it clockwise with the pliers.
Make sure the fan shroud and fan blade are snug in place, and that the water pump is tight on the motor.
Route the belt back onto the pulley the same way it came off. Tighten the belt by holding the alternator back with a pry bar or large screwdriver and tightening the alternator in place.
Alternate pouring 1 gallon of antifreeze and 1 gallon of water into the radiator. Keep mixing until the radiator is full.
Start the truck, leaving the radiator cap off. Allow the Chevrolet to warm up for at least 15 minutes. As the coolant circulates through the system, the level in the radiator will get lower; top it off as needed.
Inspecting the Installation
Tighten the cap on the radiator.
With the truck continuing to run, visually inspect for coolant leaks. Watch for water dripping off the water pump or around the motor. Let the truck run for at least 30 minutes.
Listen to the belt to make sure it is not making unusual noises. A squealing sound means you should tighten the belt more.
Turn off the truck, and let it sit for at least half an hour. This will give time for the pressure to go down. Watch the water pump as you let the engine settle. Inspect for any leaks while the water pump is not running.
Remove the radiator cap slowly, and observe the coolant level. It should be on top where you would be able to touch it. If the level is low, you should retrace your steps and figure out where the water is leaking. The water pump might not have been correctly installed, or you may have other issues.
Tips & Warnings
Be sure you have a tub big enough to catch all the waste coolant when you drain the radiator. During disassembly, remove any components that are in your way. Remember where you pulled them from so you can them reattach later.
Work on the coolant system only when the vehicle is cold; otherwise there is a chance you will be burned by hot water.
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