Fix It

Pull your car into the garage, and turn it off. Open the hood, and take off the negative ("-") battery cable.

Put a bucket under the radiator, and position it so that its centered under the drain plug. Pull the drain plug, and let all of the coolant drain out. When there is no more coolant in the truck, reconnect the drain plug.

Remove the bolts connecting the radiator shroud to the frame. Do this by getting the right size socket and turning the bolts counterclockwise. When the bolts are off, the shroud will come off easily by hand.

Check the fan shroud for a diagram of the routing of the serpentine belt. If there is no diagram, grab a piece of scrap paper and pen and draw a diagram so that you will know how to put the serpentine belt back on when your putting the new water pump on.

Find the right-sized socket that fits the pulley tensioner bolt, and loosen it just enough to remove the belt from the water pump pulley.

Take the radiator and heater hoses off of the water pump. Squeeze the clamp with a pair of needle-nose pliers so that it gets bigger, and move it down the hose. Pull the hose from the water pump. The heater hose is located on top of the water pump, and the radiator hose is on the bottom of the water pump.

Remove the bolts holding the water pump to the engine. You need to turn them counterclockwise. If you cant remove the water pump after you have removed the bolts, then take a rubber hammer and tap on the pump until it becomes loose.

Put paint thinner on a rag, and clean off any of the old gasket from the engine. This will ensure a tight seal of the new gasket.

Put some RTV sealant on the new gasket, and put the gasket on the new water pump. Put the new water pump back into the engine, and finger tighten the bolts. Use your torque wrench to make the bolts tight.

Reinstall the radiator and heater hoses on to the water pump. The radiator hose goes on the bottom and the heater hose gets attached to the top of the water pump.

Put the serpentine belt back onto the water pump. Make sure that you check your diagram to see that you are putting the belt on correctly. Turn the tensioner bolt clockwise while using a pry bar to pull the water pump toward you.

Reinstall the radiator shroud by turning the bolts clockwise.

Reconnect the negative battery cable.

Turn the car on, and let it run until it gets to running temperature. That way any air in the lines will escape out of the open radiator. When you are satisfied that there isnt any more air, then you can put the cap back on the radiator; make sure that the cap is tight.

Disconnect the cable to the negative terminal of the battery with a socket wrench. Install Fuel Pressure Gauge J 34730-1A to the fuel pressure connection on the fuel rail. Loosen the fill cap for the fuel tank, and open the valve on the fuel pressure gauge. Disconnect the fuel pressure gauge from the fuel pressure connection.

Drain the fuel tank and support it with jack stands. Remove the filler neck for the fuel tank. Disconnect the fuel tank shield and the retaining straps for the fuel tank. Detach the fuel lines and electrical connector from the fuel pump. Disconnect the fasteners for the fuel tank with a socket wrench and lower the fuel tank from the vehicle with the jack stands.

Turn the locking ring on the fuel tank counter-clockwise with a spanner wrench. Remove the locking ring and detach the fuel pump from the fuel-sending unit. Discard the O-ring that is on the fuel tank.

Install the new O-ring on the fuel tank and lower the fuel-sending unit into the fuel tank. Avoid damaging the fuel strainer as this can restrict fuel flow. Turn the locking ring clockwise with a spanner wrench. The cam-locking ring will lock into position under the locking tabs.

Connect the fuel tank to the vehicle and tighten the fasteners to 33 ft. lbs. with a torque wrench. Attach the fuel lines and electrical connector for the fuel pump. Fasten the restraining straps and shield for the fuel tank. Connect the filler neck for the fuel tank. Connect the cable to the batterys negative terminal. Start the engine check for fuel leaks.

Drive the 1999 Blazer up on car ramps to raise the front end. If you do not have car ramps, lift the front of the Blazer on a flat, level paved or concrete surface using a floor jack and two jack stands placed under the front frame rails. Apply the parking brake.

Place a wheel chock behind one of the rear wheels.

Put on the safety glasses and crawl under the Blazer (on a creeper if you have one) and bring the remaining tools with you.

Locate the oxygen sensor to replace. The bank one sensor is up under the left drivers side just forward of the front exhaust Y-pipe. The bank two sensor is located in the exhaust pipe just forward of the catalytic converter.

Follow the wire harness plugged into the oxygen sensor youre replacing. Using the small straight edged screwdriver, press in the lock clip of the plug and unplug the oxygen sensor wire from the harness.

Place the 22 millimeter wrench or oxygen sensor socket and ratchet onto the oxygen sensor and turn it to the left to release it. If it does not want to release, light the hand held portable propane torch and heat the exhaust pipe around the edge of the oxygen sensor. Do not heat the oxygen sensor, too. Just the pipe around it. Try to loosen the sensor until youre successful. If you had to use the torch, allow the exhaust pipe to cool down and just take a break.

Apply a light coat of high-temperature anti-seize lubricant to the threads of the new oxygen sensor only if there is not already some on them.

Screw the new oxygen sensor into the port. Tighten with the wrench or socket and ratchet. Do not over-tighten. The sensor only has about 4 to 5 threads and stripping those threads would be futile to the sensor.

Plug the sensor wire back into the wire harness.

Collect all the tools and debris from under the Blazer. Remove the wheel chock and lower the Blazer.

Raise the front end of your Blazer with a jack and support it with a set of jack stands positioned solidly under the frame of the truck. Remove the jack from under the truck so you dont have to try and work around it.

Locate the catalytic converter in the front of the exhaust system. On the S10 Blazer, it is located just behind the Y pipe where the two down pipes from the engine come together.

Locate the two mounting bolts on the joint at the rear of the catalytic converter where it meets the exhaust pipe. Remove the bolts with a socket and ratchet and then separate the joint.

Move to the front of the catalytic converter and locate the tow bolts that attach the converter mount to the front of the converter. Remove the bolts with a socket and ratchet. Remove the exhaust clamp just in front of the mount, using a socket and ratchet to remove the nuts from the cl then separate the two halves of the clamp.

Separate the catalytic converter from the front pipe by pulling it straight back, using a twisting motion to loosen the catalytic converter from the pipe. Remove the converter out from under the truck and set it aside.

Raise the front of your Blazer with a jack and position a set of jack stands under the front suspension to support the truck while you work under it. Lower the jack and remove it from under the truck.

Position yourself under the passengers side of the Blazer and locate the catalytic converter in the exhaust system. Find the O2 sensor on the drivers side of the case and follow the wires from the top of the sensor to the wiring harness connector.

Release the locking tab on the wiring harness connection, then separate the two halves of the connector. Place an O2 sensor socket on the sensor body and turn it counterclockwise with a ratchet. Remove the sensor and set it aside for reuse later.

Move to the rear of the converter and remove the bolts from the mounting flange with a socket and ratchet. Pull the exhaust pipe loose from the converter and push it off to one side.

Locate the flange at the front of the catalytic converter. Remove the mounting bolts with a socket and ratchet, then separate the converter from the exhaust pipe.

Locate the rubber isolator that supports the converter; slide it off the mounting pin on the frame, then lower the converter down and out of the exhaust system. Slide the catalytic converter out from under the truck.

Disconnect the negative terminal of the battery prior to starting any work. You need to do this before performing any repairs on your Blazer to reduce the risk of shock or electrical shorts while you work.

Locate the heater core on the engine compartment side of the firewall. Disconnect the inlet and outlet heater hoses from the heater core and plug the open end of the hoses to prevent debris from entering the hoses while you are working.

Remove the lower dashboard panels from both the left and right sides by turning the retaining screws counterclockwise to remove them and then depress the clips to release the panels.

Locate the pivot bracket under the dashboard at both ends of the dash. Turn the bolts on the pivot bracket counterclockwise to remove them from the dash assembly. Turn the Torx screws on the pivot brackets counterclockwise to remove them from the bracket.

Lower the steering column from the dashboard by turning the four nuts counterclockwise to remove them from the firewall bracing.

Find the steel rod brace located just to the right of center at the bottom of the dashboard. Turn the bolt at the end of this brace counterclockwise using the appropriate socket to remove it from the dashboard.

Use a flat screwdriver to pry the speaker grilles and the defrost outlet out of the dashboard. This will expose a series of bolts that are hidden behind the grilles. Turn each of these bolts counterclockwise to remove them from the dash.

Hold the dashboard and allow it to tilt towards the passenger compartment of the vehicle. Disconnect the main electrical plug and the radio antenna.

Remove the steel rod brace from the heater core. Once this brace has been removed, use the Phillips screwdriver to remove the six screws that secure the heater core cover to the housing.

Remove the screws at the top and bottom of the straps attaching the heater core to the passenger compartment side of the firewall counterclockwise to remove the support straps.

Remove the screw from the center of the strap covering the tubes leading to the engine compartment. This is located at the top-left of the heater core. Once this screw is removed, you will be able to pull the faulty heater core from the firewall and install the new one.

Reverse all steps to install the new heater core.

Loosen the lug nuts on the wheel where the bearing is defective, using a lug wrench or socket and breaker bar. Raise the front of the truck with a jack and position a set of jack stands under the frame to support the truck.

Remove the lug nuts and pull the tire and wheel off the vehicle; set it aside for now. Locate the two retaining bolts at the top of the brake caliper and loosen the bolts with a socket and ratchet.

Remove the brake caliper bolts then lift the caliper off the brake rotor and support it with a piece of wire or twine. Do not allow the caliper to hang on the brake hose, as the weight of the caliper will damage the hose.

Slide the brake rotor off the hub assembly and set it aside. Locate the castle nut in the center of the hub and remove the cotter pin that retains the nut using a set of needle nose pliers. Discard the cotter pin, as a new one will be used during reassembly.

Place a hub nut socket on the nut, and using a breaker bar, rotate the nut counterclockwise. Remove the nut from the shaft. Move to the rear of the steering knuckle and locate the three hub retaining bolts that thread into the back of the knuckle and hub.

Remove the three hub retaining bolts with a socket and ratchet. Set the bolts aside and move back to the front of the knuckle.

Separate the hub from the knuckle using a cold chisel and hammer, driving the chisel into the seam between the two pieces. Pull the hub out of the knuckle and off the axle shaft. Discard the old hub if the bearing is defective.

Turn off the engine for 10 minutes to allow the fuel system to depressurize. Disconnect the negative terminal on the battery with a socket wrench to prevent accidental sparking while you work on the vehicle. Loosen the filler cap for the fuel tank to relieve the pressure in the fuel tank.

Siphon the fuel in the fuel tank into a gasoline container. Raise the vehicle and support it on jack stands. Release the retaining clamp for the filler hose on the fuel tank and disconnect the filler hose.

Support the the fuel tank with a floor jack. Remove the fuel tank straps with a socket wrench. Lower the fuel tank slightly so you can remove the fuel lines and electrical connections for the fuel sending unit. Lower the fuel tank completely and move it to a work area.

Turn the cam locking ring for the fuel sending unit counterclockwise with GM tool No. J-24187. Remove the cam locking ring and lift the fuel sending unit from the fuel tank. Pull the fuel pump away from its bottom support, and then pull it into its mounting tube. Use care not to damage the insulator or fuel strainer.

Install the new fuel pump by performing Steps 2 to 4 in reverse order. Tighten the nuts on the fuel tanks retaining strap to 33 feet/lbs. with a torque wrench. Connect the cable for the negative terminal on the battery with a socket range and correct any fuel leaks.