is there a surefire test for the wp ?
yes and no. its tough to do anything in cold weather, but here's a series of several tests you could try if its not too cold. warning - most of this is very wet and cold.

i'm assuming you already tested your coolant and you know for sure that its not freezing up.
also be aware that wp life can be very variable, anywhere from 75k-150k miles and/or 5-10 years.

0.0 remove serp belt off the tensioner and spin/feel the wp pulley underneath the fan. wiggle it sideways and in/out. it should have none, or very very little play. if you have a lot of slop, its bad.
0.1 if you are mysteriously losing fluid, something is leaking. could be rad, wp, hose, heater core. if water leaks out, then air can leak in, and you can get an air bubble/lock, which can screw up coolant flow.
0.2 this is wet and dirty and hard to get to, but remove lower rad hose from wp. stick something up in the wp inlet pipe to hold the impeller, then try to turn the pulley (not the fan). if the pulley spins and the impeller doesn't = bad wp.

1. remove both rad hoses at top and bottom and perform flow test from inlet (not cap) to outlet w/garden hose. water should flow through easily, run out the bottom fairly strong, and not backup excessively
2. remove t-stat completely and inspect it. test it in a pot of water on the stove with a meat thermometer. verify that it opens at 180 or 195, whatever its rated at. t-stat should lay in the pot sideways, so the sensor is not directly on the bottom of the pan. meat therm should only touch the water, not the pan.
3. reinstall rad hoses, t-stat neck - no thermostat and run it in the driveway with water only not anti-freeze. (save your money for the time being). don't worry about a perfect gasket seal or minor leaks. install top and bottom rad hoses very loosely with no clamps. fill system. start truck and continue to fill system until its completely full and primed.
4. be careful not to get burned here - observe coolant flow through top and bottom rad hose. flow should be strong, engine should remain fairly cold since you have no t-stat, no possible air lock, and no possibility of stuck t-stat. stick garden hose into rad cap and run at med flow to maintain water supply - then remove top rad hose from rad temporarily and observe flow coming out (onto the ground). flow should be strong (and warm). if not, definitely bad wp. if engine overheats with no t-stat you've either got bad wp or blown head gasket or some other kind of flow problem. if all is well, take it for a test drive.

5. if t-stat tested in pot of water ok, then drill a small 1/16 - 1/8 hole in the inner edge of the outer flange. reinstall with gasket and refill and retest. this should hold water inside the engine and warm up to normal temp.

6. if all this gets you to an all is well, drain rad and refill it with anti-freeze. you have 1-2 gal inside the block, so a rad full of a/f will give you something close to a 50/50. since you live in cold area test it to make sure you've got enough a/f.

this is a long drawn out post, and a long drawn out test procedure, but something along the way should fail.

 

WOW! Thanks for the advice!! Well, it is now snowing along with being extremely cold, so I will have to buy my friend a 12 pack and get into his shop. I will take each step and give it a try. I cringe when you say blown head gasket!!! I can say there is no leaks but I will still try all steps to rule out water pump. Hell, I dont think they are too expensive, I may as well just replace the damn thing! I plan on having this truck a while anyway. This could save me all the steps! Thanks again!

 

ALRIGHT!!!!! I started with the $5 thermostat....no fix. Spent the last 3 hours replacing the water pump....no fix!!!! Do I move on to the radiator??? Still is overheating, yet no heat in cab!!! There is obviously no circulation of coolant, right??? Is this pointing to the radiator since I did everything else???[:@][:@][:@][:@] Thanks!

 

try letting it run without the coolant hose cap on to get out any air in there. then if the truck warms up and you still have no heat you can rule out the radiator.

 

my 91 camaro had the same problem . i did everything that i could think of . i even had a couple of shops flush the system. i finally took it to the dealer and they found that one of my hard lines going into the intake was clogged . it took them about 20 mins to find something that i spent 2 months to try and fix myself. i could have saved myself so much money.

 

Ok....So what should I do? If I get the air out and it still overheats......then what? Paxmaster, how did you get the hard line unclogged? This is driving me crazy!!

 

Flush the whole system hook a hose up to everything. Check your gycol level with a tester. Does it bubble down when you start it? If there is anything clear ish floating around it is probably ice. But best bet put lots of antifreeze (upto -30 should do the trick.... I bet one of your hoses is clogged or something. )

 

Just my two cents worth, but I had a Jeep, "before Chrysler made them", and it had similar problems. Changed everything, and it ended up being a head gasket. For what it cost to change everything else, I could have done the head gasket. The dip stick showed no coolant or sludge either which made us think originally it wasn't the head gaskets. Also, I had a radiator cap go bad that caused the cooling system to act up on a different vehicle. Just wanted to contribute, as I know what a pain in the butt these problems are.

 

i'm just trying to go through it step by step...
don't panic yet, sometimes you get an air bubble that blocks flow. just treat it like any plumbing problem. the only real mystery is could a head gasket leak be pushing high pressure into the water chamber which will disturb and/or block water flow. a compression test and/or cylinder leak down test might be needed to identify this.

did you try running it with no thermostat installed and top radiator hose removed, so you can see the coolant pumping out of the engine and to the rad ?

did you try the radiator flow test with water into the inlet (not the cap) and flowing through to the outlet ? if you're not getting flow out of the rad, then wp can't do its job. you can simulate/test this by removing lower hose at rad and turning it up and putting a water hose into it to ensure plenty of flow.

 

I know this is going to seem a bit simple, but when the truck is overheating, are all the heater hoses hot and tight like they are under pressure? If not that definately narrows the possibilities down. My advise would be to #1 check the hoses with the truck hot, and if they all are hot, go to your local auto parts store and rent a radiator pressure tester. Apply the same pressure with the tester as what it says on the cap. Pressurize the system and just watch the gauge. If you are loosing pressure and you don't have any water leaks, odds are its a bad head gasket.