aron5823

I have a 2001 QC 4x4. I noticed the other day that it seemed to take forever for the heater to get warm. 15 min drive and the gauge is a little over the 140 mark and luke warm air is coming out of the vents. Just got back from an 25-30 mile jaunt with some good grades....temp gauge a tad over 190 on the pull and on flat ground at highway speeds....it had a tough time keeping 190(184-186 according to the attitude)and heater output is warm not hot. Once I got home and popped the hood and then removed the radiator cap....very little pressure and warm almost cool water. The drivers side of the radiator is hot and the passengers side is cool. I figure that if the water pump is dead, the motor would heat like crazy. Any suggestions or ideas would be greatly appreciated.

robert78.5

What was the outside temp?

aron5823

High 30's low 40's

robert78.5

Your cooling fan is not stuck on is it?

aron5823

Nope. Fan cycles when you first start it, then shuts off like normal. Baffles me that even if it was running constantly, you wouldn't think one side of the radiator would be cool to the touch.

00 CTD

Easiest thing is to change the thermostat if the original one is still in there.

aron5823

Thermostat has been changed a couple of times. Easy to do and cheap...I'll let you know. Thanks

robert78.5

We had something similar at work on a farm tractor. A baffle inside of radiator had let go and was down on top of half of the tubes, stopping circulation on half the rad. Just an idea.

aron5823

I figure I'll start with the thermostat and yank the radiator next. Thanks!

aron5823

Changed thermostat. It still seems to take forever to build heat and the air coming out of the vents is warm not hot. If the fan clutch is bad, is there any way to verify?

00 CTD

Thermostat was the easiest to change, and it didn't help it, can rule that out.

In your first post, you mentioned the radiator hot on one side, cold on the other. That's a sign of a water pump problem, the impeller spinning on the shaft. When the system's operating correctly, you're only going to see a 10-20* difference between the inlet and the outlet of the radiator.

Some years back we had a truck in the shop not blowing any heat. Changed the thermostats, did some checks, everything looked OK. It had a new water pump on it. Come springtime, it was in for overheating, would up pulling the water pump, the impeller was just spinning on the shaft.

aron5823

Is there a simple check for the fan clutch? When the motor is cold it will move with one finger. Should it spin freely or will there always be a little resistance?

Dinner

There should always be resistance with a Viscous Fan Clutch. Should be able to spin it around, but once you stop putting force on the blades, the fan should stop.

aron5823

It appears that I have covered all of my bases. Thermostat replaced...check old one for kicks and giggles and it opens at 190. Fan clutch spins with a little resistance. Some where it is suggested that the water pump impeller may be spinning on the shaft....but wouldn't it heat up rather than run on the cold side. Any other ideas?

nickg

What brand of thermo did you instal?? just cause you changed it does not rule it out, My experience (22yrs as a Mechanic) is that some brands are crap, motorad to name one, most cheaper parts stores carry them, and I've yet to see one work properly out of the box and if it does it wont last a year. I've had positive results with Stant heavyduty thermostats, and usually most OEM ones work best.

when you tested your old thermo was it completely open at 190* or did it start opening sooner? like at 140-150 did it start to open slightly. once it starts to open the waterpump can flow coolant past it, causing a longer warm up time

you could block the rad off with cardboard to see if you can build heat. as it will more than likely help alot. a winterfront will help hold heat, especially at hiway speeds

I can't remember ever seeing a waterpump impeller slip on the shaft or have seen one that the blades rotted off I've heard of it but in 22yrs twisting wrenches, have never personally seen it, unless the bearings in the pump gave out and it tore up the impeller. I'm not saying it cant happen, but it would be rare. A simple test to see if it works is when the engine is up to temp, raise the rpm a little and pinch the upper rad hose off with your hand, when you release the hose you will feel the rush off coolant pulsing thru the hose, this will only truely show when the thermo is open, if the thermo is closed it aint gonna work. again you are right if the pump aint working you would have an overheat issue, not an over cooling problem. on the flip side If I had a dollar for every waterpump I've seen replaced because a veh was running hot/overheating I'd be pretty well off (well its a bit of an exageration) most always it's an externally or internally plugged rad, cause most folks change the thermostat and if that does not fix it they fiqure the waterpump dont work.....

so after all my rambling, I'd sum it up to this
1) replace thermostat with a high quality unit, OEM or Stant HD
2) if the above is done instal a winterfront or the redneck version...cardboard