Service engine light is on

The timing belt could have been loose, or the tensioner not set correctly. It sounds as if your timing belt has slipped.

for a water pump to lock ( seize) it would have had bearing failure in the pump. that will require a new water pump. It is possible of obstruction in the impellor section but this would be unlikely. When water pump bearins fail you will normally hear a low tinny metal growl at low rpm long before seizure occurs

Place front end on jacks or ramps. I belive there is a lower plastic guard that protects the serpintine belt from water splash ( I know the 96's did not have it but uncertain about 1997, is so remove it) Drain radiator/cooling system. The serpintine belt will have to be removed, you'll need to use a box end wrend on the tensioner to remove pressure from belt, it will fight you but she will go. Next remove bolts that hold pulley on to water pump shaft (I believe there are three, all 10MM) next remove all of the bolts that hold the water pump on, I belive there are either 5 or 6, either 8 or 10MM. Clean surface where pump applies to, be certain to use new o-ring, should be with water pump. Reassemble in reverse, install new serpentine belt and use proper 50/50 mix of radiator fluid and water. Start engine, let it come to heat and check for leaks, keep eye on temp gage to be certain things are ok.

I hope this may have assisted you,
Tom

3.5L Engine

Remove or disconnect the following:

1. Negative battery cable
   

• Engine coolant
  
• Water pump pulley bolts
  
• Alternator bolt, loosen only
  
• Water pump pulley and drive belts
  
• Crankshaft pulley
  
• Timing belt cover(s)
  

1. Turn the crankshaft until the timing marks on the camshaft sprocket and cylinder head are aligned.
   
2. Loosen the timing belt tensioner bolt and turn the tensioner counterclockwise as far as it will go. Tighten the adjusting bolt.
   
3. Mark the timing belt with an arrow showing direction of rotation.
   
4. Remove the timing belt.
   
5. If defective, remove the timing belt tensioner.
   

Timing belt sprocket alignment mark positioning for belt removal and installation—3.5L engine

To install:

1. If necessary, install the timing belt tensioner.
   
2. Attach the top of the tensioner spring on the engine coolant pump pin. Ensure the hook on the pin is facing down and the hook on the tensioner is facing away from the engine
   
3. Rotate the timing belt tensioner to the extreme counterclockwise position. Temporarily lock the tensioner in place.
   
4. Align the timing marks of the camshaft and crankshaft sprockets.
   
5. Install the timing belt on the crankshaft sprocket, then onto the rear camshaft sprocket.
   
6. Route the belt to the coolant pump pulley, the front camshaft sprocket and the timing belt tensioner.
   
7. Apply force counterclockwise to the rear camshaft sprocket with tension on the tight side of the belt and check that timing marks are aligned.
   
8. Loosen the tensioner bolt 1–2 turns and tighten the timing belt to a tension of 57–84 lbs. (260–380 N).
   
9. Turn the crankshaft two turns clockwise.
   
10. Readjust the sprocket timing marks and tighten the tensioner bolts.
    
11. Install the timing belt covers.
    
12. Install the crankshaft pulley and tighten to 108–116 ft. lbs. (150–160 Nm).
    
13. Install or connect the following:
    
    • Timing belt cover(s)
      
    • Crankshaft pulley
      
    • A/C compressor belt
      
    • Water pump pulley
      
    • V belt
      
    • Negative battery cable
      
    • Engine with coolant
      

Changing a water pump is pretty basic. Since the coolant system is a closed system you only need to be concerned with that system. For instance you since you have to mess around with it anyway you might as well change the thermostat and flush the coolant system. Make sure your radiator hoses are in good shape and that's about it.
If you have basic mechanical skills and tools you will have no problem replacing a water pump.


As far as information with the actual replacement there are a number of experts here including myself that could explain how to do it.
However no matter how good our explanations are it just can't compare to a good repair manual.
A repair manual for your car at Auto Zone would likely cost between $12 and $15. It is a great investment if you are going to keep your car for any length of time. When you sell, it shows the buyer you took the time to maintain and repair it right.
I personally like Haynes Manuals.
I hope this helps.

buy new pump and then proceed to take off front of engine as that is where pump is located will be right behind fan blade

Installation > 5.9L Diesel Engine 5.9L Diesel Engine
WARNING Do not attempt to check belt tension with a belt tension gauge on vehicles equipped with an automatic belt tensioner.

Drive belts on diesel engines are equipped with a spring loaded automatic belt tensioner. This belt tensioner will be used on all belt configurations, such as with or without air conditioning.

1. Depending on the year of the vehicle, a 3/8 inch or 1/2 inch square hole is provided in the automatic belt tensioner. Attach a 3/8 inch or 1/2 inch drive-long handle ratchet to this hole.
   
2. Rotate ratchet and tensioner assembly clockwise (as viewed from front) until tension has been relieved from belt.
   
3. Remove belt from water pump pulley first.
   
4. Remove belt from vehicle.
   

To install:

WARNING When installing the accessory drive belt, the belt must be routed correctly. If not, engine may overheat due to water pump rotating in wrong direction. The correct belt with correct length must be used. Position drive belt over all pulleys except water pump pulley.

1. Attach a 1/2 inch ratchet to tensioner.
   
2. Rotate ratchet and belt tensioner clockwise. Place belt over water pump pulley. Let tensioner rotate back into place. Remove ratchet. Be sure belt is properly seated on all pulleys.
   

The serpentine belt tensioner / pulley is on the front of the engine, and part of the belt 'routing'.

Its job is to put tension on the belt as it drives the other devices like the power steering pump, water pump, air conditioning compressor.

It is an aluminum casting that mounts with a single bolt to the engine. The pulley is attached to the arm.

There are a few ways to move / pry the arm inwards, thus releasing the tension on the belt for removing/installing: grab on the pulley bolt (15mm?) with a wrench, or some later models have an opening for a 3/8th socket wrench to attach to directly without a socket.

1. Let me know if you cannot see diagrams(happens sometimes) or if you have any questions

Just to make sure. I assume that you are seeing coolant leakage from around the water pump assembly.

1. 
   
2. Disconnect the negative battery cable.
3. Place fender covers on the aprons.
4. Drain the cooling system.
5. Remove the accessory drive belts.
6. Remove the timing belt cover.
7. Use a wrench on the crankshaft pulley to rotate the engine so No. 1 piston is on TDC of the compression stroke.

Turn the engine only in the direction of normal rotation. Backward rotation will cause the timing belt to slip or lose teeth.

1. Loosen the belt tensioner attaching bolts, then secure the tensioner over as far as possible.
2. Pull the belt from the camshaft, tensioner, and water pump sprocket. Do not remove it from, or allow it to change its position on, the crankshaft sprocket.

WARNINGDo not rotate the engine with the timing belt removed or serious engine damage could occur. The 1.3L and 1.6L engines are of the "interference type," meaning it is possible for the valves to contact the pistons if their reciprocation is not carefully timed and controlled. An engine allowed to spin freely without the timing belt could bend valves and scuff pistons almost instantly.

1. Remove the camshaft sprocket.
2. Remove the rear timing cover stud.
3. Remove the heater return tube hose connection at the water pump inlet tube.
4. Remove the water pump inlet tube fasteners and the inlet tube and gasket.
5. Unfasten the water pump to the cylinder block bolts and remove the water pump and its gasket.

Fig. 1: If equipped, remove the cover from the water pump Fig. 2: Unfasten and remove the heater return tube hose connection at the water pump inlet tube nuts from the studs Fig. 3: Location of the water pump mounting bolts-1.9L engine Fig. 4: After unfastening the water pump retaining bolts, remove the water pump from the engine compartment Fig. 5: If you are reusing the old water pump, remove the gasket ... Fig. 6: ... and carefully clean both of the water pump mating surfaces using a gasket scraperTo install:

1. Make sure the mating surfaces on the pump and the block are clean.
2. Using a new gasket and sealer, install the water pump. Tighten the bolts to 30-40 ft. lbs. (40-55 Nm) on 1981-87 models, or to 15-22 ft. lbs. (20-30 Nm) on 1988-90 models. Make sure the pump impeller is able to turn freely.
3. Install the water pump inlet tube and the inlet tube gasket and fasteners.
4. Install the rear timing cover stud. Install the heater return tube hose connection at the water pump inlet tube.
5. Install the camshaft sprocket.
6. Install the belt from the camshaft, timing belt tensioner, and water pump sprocket.

Fig. 7: Radiator hose-to- engine mounted water pump inlet tube-gasoline engines Fig. 8: Exploded view of common water pump inlet tube and related fasteners-non-A/C type Fig. 9: Exploded view of water pump and related components-1988-90 1.9L engineDo not rotate the engine with the timing belt removed.

1. Tighten the belt tensioner attaching bolts, then secure the tensioner over as far as possible.
2. Install the timing belt cover.
3. Install the accessory drive belts.
4. Refill the cooling system and reconnect the negative battery cable.

There is a pulley thast moves around a little when the engine is running, this is the belt tensioner pulley, you will need either a special wrench or a ratchet to release the tension on the belt.