Cooling fan

[Darol Wester]

Might be your A/C problem too. Good call High.

Fan Clutch Trouble Shooting
Faulty fan clutches can be detected by checking for obvious indications of failure such as:
?
Leaking fluid
- oily build up around the bearing or thermal spring.
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Bad bearing
- seized, turns rough or has excessive play (more than 1/4? at fan tip).
?
Worn thermal spring
- spring is loose.
Some fan clutches will show no visible indication of a problem yet may still be faulty.
The following may also indicate a faulty fan clutch
:
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Fan spins excessively
- three or more times when hot engine is shut off.
?
Poor air conditioning
- At low speed due to excessive high side refrigerant pressures.

Doesn?t engage or ?lockup?
- Fan speed does not increase when engine is hot.
?
Does not disengage
- Fan clutch won?t slow down when engine is cold

 

[Kyure]

Thanks. I know it takes time to look things up, your help is appreciated..now to start testing it.

 

[highup]

Have you ever changed the coolant in the radiator?
What color is the coolant? Green or Orange?

Check it out. Here's why I asked.
https://www.google.com/?gws_rd=ssl#safe=off&q=photo+of+Dex+Cool+mixed+with+Green+stuff

 

[Kyure]

That would suck mixing it eesh. My brother flushed out the orange and put the green 2 summers ago and it still looks clean in the cap. As far as fan goes I can't see leak or looseness

 

[Darol Wester]

Chevy Truck Forum

By
Fast305


Re: Radiator fan 2001 Express 5.7


Without any modifications needed his (Kyure) best bet would be an AC Delco clutch or a Napa Premium Severe duty clutch and a multi bladed GMT400 tow package fan.

 

[Darol Wester]

First picture....Stock 5 blade vs 4.3 S10 fan

Second....GMT400 Tow vs Early Duramax

Sorry, couldn't get the pic's in the first go round.

 

[highup]

I'm now voting against the sensor being an issue.
I see these as the most likely issues.

Mentioned at the beginning were a faulty thermostat. If it sticks open or partially open, then engine will never reach operating temperature............ that explains the gauge never moving much.

A clogged heater core was mentioned. That would explain cold air blowing from the heater.
Since the heat gauge on the dash doesn't move much, if at all, that makes me go back to the thermostat being failed in the open position.

Here is some information on that mechanical fan clutch.
http://en.wikipedia.org/wiki/Fan_clutch
Within this article it says:
"Another potential symptom of fan clutch failure (always drawing air at a high rate) in a cold weather climate is that the heating system blows lukewarm air never delivering sufficient hot air"

These thermal clutches do fail.
http://www.aa1car.com/library/cooling_fan_clutch.htm
This article mentions that the clutch should be replaced at the same time as the water pump:

" Many experts say it is a good idea to replace the fan clutch at the same time as the water pump if the water pump has failed. The reason is because both age at about the same rate, so if the water pump has failed, the fan clutch may also fail soon. As as we mentioned earlier, a high mileage fan clutch may be slipping excessively increasing the risk of overheating.

When you buy a replacement fan clutch, make sure you get the same type (thermal or nonthermal) as the original. You can always upgrade from a nonthermal to a more efficient thermal fan clutch, but never the reverse. Or, you can get rid of the fan and clutch altogether and install an aftermarket electric fan kit to cool the radiator"

Here's what it says about diagnosing a fan clutch:

"CHECKING THE FAN CLUTCH

A good clutch should offer a certain amount of resistance when spun by hand (engine off, of course!). But if the fan spins with little resistance (more than 1 to 1-1/2 turns), the fan clutch is slipping too much and needs to be replaced.

If the fan binds, does not turn or offers a lot of resistance, it has seized and also needs to be replaced.

Fan speed can also be checked with an optical tachometer, by marking one of the fan blades with chalk and using a timing light to observe speed changes, and/or listening for changes in fan noise as engine speed changes.

You should also try to wiggle the fan blades by hand. If there is any wobble in the fan, there is a bad bearing in the fan clutch, or a worn bearing on the water pump shaft. A bad water pump bearing will usually cause the water pump to leak and/or make noise, but not always. Remove the fan clutch and see if the play is in the water pump shaft. If it feels tight (no play or wobble), replace the fan clutch."


So first, check to see if the fan blade is hard to turn when the engine is cold........... and hot......... engine off of course. The fan clutch will allow the fan to be turned by hand. If it's overly difficult to turn, it may contribute to, or be the cause of the problem.

If it seems OK, replace the thermostat with a good one like Stant.
http://www.stant.com/index.php/english/products/consumer-products/thermostats/superstat-thermostat/
There is a thermostat brand called Fail Safe, but I think I would avoid that one. I've read good and bad things about it.

 

[highup]

You guys are right, told ya I'm not to keen. Going to replace the sensor today.

OK, not being "too keen" is a good reason to ask. Not everyone was brought up around automotive mechanics. Not everyone was brought up around floor covering installation either.............. that's why the internet is so neato.

 

[Kyure]

Thanks high and Darol. That's alot of work testing but I guess needs to be done. I did check for play in fan and did spin test, nothing seems off there. I'll test or just replace thermostat next then delve into the other stuff you posted.

 

[highup]

Thanks high and Darol. That's alot of work testing but I guess needs to be done. I did check for play in fan and did spin test, nothing seems off there. I'll test or just replace thermostat next then delve into the other stuff you posted.

I never have tested a thermostat. Once you go to the trouble of removing it, you are better off just putting a new one in. They last a long time if you buy a good one. You might consider replacing the upper radiator hose while you are at it. Those don't last forever, and if it's old, now would be the time to do it.
I don't know if the vehicle you have has what is called a closed system. I'll do come checking on that. Those systems don't like any air in the radiator, and I think you refill them through the upper radiator hose so all the air is removed............. Like I said, I'll do some checking on it.