I'm talking about the metal cooling hose that goes from the back part of the water pump to the thermostat in the back part of the engine closest to the fire wall it is behind the engine. metal pipe is leaking coolant and want to change it out. is it difficult to do. do i need to remove a lot of things.

replace the temperature sending unit. Its right there by the thermostat. You can get this at any auto parts store. just need an open end wrench to change it. they do go bad(found out the hard way several years back). I hope this helps you

Please see my tip at http://www.fixya.com/cars/r5929960-s_thermostat .

Specific instructions for your car are as follows. Let me know if you get stuck or have more questions.

Removal & Installation

4.2L Engine

1. Remove the necessary coolant from the radiator.
2. Remove the alternator, as outlined in the Engine Electrical Section.
3. Loosen the outlet hose clamp at the thermostat housing. Remove the outlet hose from the thermostat housing.
4. Remove the thermostat housing bolts.
5. Remove the thermostat housing from the engine block.
6. Clean all of the surfaces of the thermostat housing.
7. Clean the sealing surface of the engine block.
   

To install:

1. Install the thermostat housing to the engine block.
2. Install the thermostat housing bolts and tighten to 89 inch lbs. (10 Nm).
3. Lubricate the inner diameter of the radiator hose with engine coolant.
4. Install the outlet hose to the thermostat housing. Secure the hose with the clamp.
5. Install the alternator.
6. Fill the cooling system with specified coolant and concentration.
7. Inspect all sealing surfaces for leaks after starting the engine.

5.3L Engine
NOTE The thermostat is not serviceable separately. The water pump inlet and thermostat must be replaced as an assembly.

1. Drain the cooling system to a level below the thermostat.
2. Remove the radiator outlet hose.
3. Remove the water pump inlet bolts.
4. Remove the water pump inlet and thermostat from the water pump.

To install:

1. Install the thermostat and thermostat housing to the water pump.
2. Install the thermostat housing bolts. Tighten the bolts to 11 ft. lbs. (15 Nm).
3. Install the radiator outlet hose.
4. Properly fill the engine cooling system and check for leaks.

To find the thermostat follow the top radiator hose. It should go into a metal fitting that has a metal clamp around it. There may be 2 bolts holding in place. Make sure that the engine is cool before trying to remove the hole. Place a container under the truck to catch the liquid. Slowly remove the hose. You should see the thermostat at the bottom of the thermostat housing. If you remove the thermostat be sure to have a new gasket. The thermostat should be less than $100.00. good luck

the water pump and thermostat should have solved it. an air pocket can cause that but usually not to that degree.

don't get one of those cheap *** plastic impeller water pump for sissies. Get the metal impeller one. get a cool running thermostat and drill two 3/16" holes in it 180 degreess from each other. you may have installed the t-stat backwards.

It Depends on which engine you have, this is how it goes for both. I use a little RTV with a new ring as well.

THERMOSTAT REPLACEMENT (4.2L ENGINE)
Removal Procedure
1. Remove the necessary coolant from the radiator.
2. Remove the generator.
3. Loosen the outlet hose clamp at the thermostat housing. Remove the outlet hose from the thermostat housing.
4. Remove the thermostat housing bolts.
5. Remove the thermostat housing from the engine block.
6. Clean all of the surfaces of the thermostat housing.
7. Clean the sealing surface of the engine block.
Installation Procedure
1. Install the thermostat housing to the engine block.
2. Install the thermostat housing bolts.
Tighten: Tighten the bolts to 10 N.m (89 lb in).
3. Lubricate the inner diameter of the radiator hose with engine coolant.
4. Install the outlet hose to the thermostat housing. Secure the hose with the clamp.
5. Install the generator.
6. Fill the cooling system with specified coolant and concentration. Follow the correct cooling systen bleed procedure for your engine.
7. Inspect all sealing surfaces for leaks after starting the engine.
THERMOSTAT REPLACEMENT (5.3L ENGINE)
1. Drain Radiator and remove the radiator outlet hose.
2. Remove the water pump inlet bolts.
3. Remove the water pump inlet and thermostat from the water pump.
Installation Procedure
IMPORTANT: The thermostat is not serviceable separately. The water pump inlet and thermostat must be replaced as an assembly.
1. Install the thermostat and thermostat housing to the water pump.
2. Install the thermostat housing bolts.15 N.m
3. Install the radiator outlet hose.
4. Fill the cooling system with specified coolant and concentration. Follow the correct cooling systen bleed procedure for your engine.
5. Inspect all sealing surfaces for leaks after starting the engine.

need water pump has plastic torbine and slips off metal gear so change water pump and thermostat

it may be a little off, but the lower water hose seldom gets very hot,, as its this hose that suplyes the engine with ""cold water"" the hot water comes out the top hose,, drains down the rad and cools on the way down then enters the engine through the bottom hose """if your engine stayes running in the normal place on the gage,,,and not over heating""" why are you spending money for nothing???""
you wont get the bottom hose to run hot unless the engine is cooking

3.7L/4.7L:LOCATED IN LOWER HOUSING ATTACHED TO TIMING COVER..WHERE LOWER RAD HOSE GOES TO ENGINE..PLASTIC HOUSING WITH 2 BOLTS.
5.7L:IN WATER PUMP UPPER HOUSING WHERE METAL HOUSING ATTACHES FROM UPPER RAD HOSE..MAKE SURE ON ALL ENGINES YOU REMOVE BLEED PLUG WHEN REFILLING COOLING SYSTEM TO GET RID OF AIR TO PREVENT ENGINE OVERHEATING

Follow the top rad hose to the engine, where it connects that's the thermostat housing.

If it's the 3.0L Vulcan Engine (OHV), the thermostat is on the driver's side of the vehicle. Follow the upper radiator hose back to a metal area with three 10mm bolts. This is the thermostat housing. Undo the bolts, and there's the thermostat. Mark the back of it with the old thermostat in it (if you get one with a jiggle valve, it'll make it easier to put the new one in because the jiggle valve needs to be on top). The thermostat and housing aren't perfectly round, so you'll have to play with it a little to get it to line up. Make sure to change the gasket. The spring side of the thermostat goes into the engine.

The water pump is in the serpentine assembly. It's the larger pulley located toward the firewall. It'll be easiest to remove the water pump if you also remove the coolant recovery tank. The water pump pulley has four 1/2" bolts that you need to take out WITH THE BELT STILL ATTACHED. I can't stress this enough. The belt will keep the pulley in place so that you can remove the bolts. Take the pulley off, then the belt. Remove the heater hose at the top and the radiator hose at the bottom. There are 12 bolts of two diameters (1/2" and 10mm if I'm not mistaken). Tap the heater hose lightly with a soft-faced mallet to break the seal with the gasket. Trash the old gasket. Replace gasket (you can also line the mating surface of the water pump with RTV Sealant, put the new gasket on the new pump, and line the other side of gasket with a second coat of RTV sealant if you want a really good seal). Install the water pump and torque to manufacturer's specs. Attach the pulley to the water pump hand tight and put the belt back on. Tighten the pulley bolts. Put the coolant recovery tank back in place. Fill with coolant, start engine, bleed and check for leaks.

To bleed cooling system: Idle the engine until the thermostat opens (you'll be able to tell bacause the upper radiator hose will be uber hot and you'll feel coolant running through this hose). Squeeze all hoses in the system that you can reach, but don't burn yourself. Stop the engine and let it cool. Open the radiator cap and squeeze the COLD upper radiator hose. You'll see some bubbles in your recovery tank. You might have to monitor your coolant level for a couple of days while the final bits of air are purged through your radiator cap (that's why it's pressurized).

Hope this helps. It's not hard, but it took me quite awhile.