Replaced 2003 water pump does it need thermostat

Airbound more than likely..if not then check flap motors on heater box.

I’m happy to assist further over the phone at https://www.6ya.com/expert/howard_977676954994c5b2

I can't give you any specifics on how to change your water pump, but I can answer your questions about the thermostat. Yes, the heat will work withou a thermostat. And yes, a car will overheat without one, especially in the summer months. The purpose of a thermostat is to allow cooler water to flow into your block, but also to allow the water adequate time to be cooled in the radiator. Without the thermostat, water is continuously cycling through your coolant system, getting hotter and hotter. Often I see people with malfunctioning thermostats jsut remove them, sometimes on the side of the road, just to get where they're going.

It's located behind the timing belt. It's not a small job. If you remove all the covers over the timing belt you can see a large aluminum plate with a hose fitting on it that goes towards the drivers side of the car. The thermostat is enclosed under that plate. If you venture to replace the thermostat you might as well replace the timing belt, tensioner, and water pump while you are in there. The water pump is driven by the timing belt.

4.8L, 5.3L & 6.0L Engines

1. Remove the air inlet duct.
   
2. Drain the cooling system.
   
3. Remove the radiator outlet hose.
   
4. Remove the thermostat housing bolts.
   
5. Remove the thermostat from the water pump housing.
   

The O-ring seal is integral to the thermostat housing

Thermostat housing-4.8L, 5.3L and 6.0L engines

To install:

1. Install the thermostat to the water pump housing making sure the spring side is inserted into the engine.
   
2. Install the bolts.
   
   • Tighten the bolts to 11 ft. lbs. (15 Nm).
     
3. Install the radiator outlet hose.
   
4. Fill the cooling system.
   
5. Install the air inlet duct.
   
6. Test the system for leaks.
   

// // 0) preLoad.src = ctl00_cphLeft_chRepairTreeNav_tvTOC_ImageArray[i]; } ctl00_cphLeft_chRepairTreeNav_tvTOC_Data.lastIndex = 26; ctl00_cphLeft_chRepairTreeNav_tvTOC_Data.populateLog = theForm.elements['ctl00_cphLeft_chRepairTreeNav_tvTOC_PopulateLog']; ctl00_cphLeft_chRepairTreeNav_tvTOC_Data.treeViewID = 'ctl00$cphLeft$chRepairTreeNav$tvTOC'; ctl00_cphLeft_chRepairTreeNav_tvTOC_Data.name = 'ctl00_cphLeft_chRepairTreeNav_tvTOC_Data'; //]]> var _strTreeScrollHidName = 'ctl00_hidTreeScrollPos';

replace the cap--is the radiator damaged? No reason to replace the water pump. Boiling is caused by leak, faulty thermostat, clogged radiator, or head gasket.

unless the thermostat was malfunctioning it need not be replaced

The thermostat is located in the water pump on mostn never Chevy trucks. If you pull the upper fan shroud, you should see the thermostat housing. Remove the radiator hose, then the 2 bolts for the housing. Replace the thermostat, and gasket together.

1. (This is for a 2.2L engine) If equipped with an automatic transmission, remove the exhaust manifold.
2. Drain the cooling system.
3. Remove the thermostat housing to water pump feed pipe bolts.
4. Remove the thermostat housing to water pump feed pipe.
5. Remove the thermostat.

check the casting on your replacement water pump..4.0l engines require a reverse rotating water pump..may be causing your problem.

FACEING the ENGINE It is At TOP RIGHT SIDE Close to Master Cylinder takes About 1 hour to Replace Have Fun its a EASY One
Please Dont forget to RATE ME Thank You

1. Drain the cooling system.
2. Remove the bolts that secure the thermostat housing to the water pump feed pipe.

Remove the feed pipe

1. Remove the thermostat and retaining sleeve, noting the orientation for installation.

Installation Procedure
Install the thermostat and retaining sleeve with the dimple placed into the housing slotImportant: Lubricate the O-ring with soapy water or coolant before installing the O-ring in the water pump.

1. Install the feed pipe that connects the thermostat housing to the water pump.Notice: Refer to Fastener Notice in Service Precautions.
   
   
   1. Install the bolt that secures the water pump feed pipe.
   • Tighten the bolt to 10 Nm (18 inch lbs.) .
   1. Fill the cooling system.