Fan Clutch 2006+

[RyansTBLS]

So I think I have figured out that I have a bad fan clutch. I'd been hearing the turbo noise, and traced it to the engine. I checked all the pulleys and replaced the whole belt tensioner assembly (should have been done a while ago). It helped the noise but didn't stop it, tried spinning the fan when it was cold and it spins all the way around. It did not used to have any play in it. Reading through my manuals I have the wonderful EV fan and clutch is gone on it, so its in failed mode. I checked the relay and the relay is fine. Reading through it looks like the Hayden is the best replacement. I get three options for the Hayden through Rock Auto: The thermal fan without the electronic clutch (part # 2851) and the thermal with the electronic fan clutch (part 3200), the third option is part 3201 which looks like its the same. Part 3200 has this to say about it:
Fan Clutch; Electronic

Electronic - Viscous EV Fan Clutch Operation

The ECM/PCM signal controls the level of engagement of the EV clutch. An internal solenoid opens a spring loaded valve which allows silicone drive fluid to flow from the storage reservoir to the working area of the unit engaging the clutch. This engagement process is ultimately controlled through the ECM/PCM by the following input variables: Coolant Temperature, Intake Manifold Temperature, Transmission Oil Temperature, A/C Pressure and Engine Oil Temperature. These variables are manufacturer specific and fan speed is dictated based on the level of cooling required. Please consult the Original Equipment specifications to determine which set of variables apply to your vehicle.

Electronic-Viscous Fan Clutch Troubleshooting During engine start up, the EV fan clutch will engage and match engine speed for up to 3 minutes. This is considered normal and may last more than 3 minutes in cooler climates or at lower driving speeds resulting in fan roar. This condition will cease shortly upon disengagement. Additionally, you may hear an audible “clicking" sound when the vehicle is stationary. These conditions are normal and should cease once the fan clutch disengages.

IMPORTANT:
• Do NOT replace EV fan clutch unless a specific issue is identified by proper SI (Service Indicator / Check Engine) diagnosis.
• Do NOT replace an EV fan clutch for fan noise.
• Do NOT replace an EV fan clutch unless a specific condition related to the EV fan clutch is identified using SI diagnostics. If the EV fan clutch has a condition that warrants replacement, a DTC (Diagnostic Trouble Code) should set and/or SI diagnostics should lead to the replacement of the fan clutch.
• Do not attempt to replace EV Fan Clutch without proper tools. Please refer to manufacturer requirements for proper tools and replacement.

Am I stuck with this darn thing until I get an engine code? Can I just replace it with a thermal? Or do I have to replace it with another EV?
I do have an OBD 2, and I have zero codes for the whole truck.

[Trail X]

Turbo noise isn't generally the fan clutch. Fan clutch is normally presented with a very loud fan noise, and often a CEL. Normally a turbo noise is one of the bearings on the serp belt. They are admittedly hard to track down though, in my experience. Normally its either the tensioner or idler. If its not those, the parts get more expensive and it doesn't make as much sense to just shotgun them.

[RyansTBLS]

Yea it is more of a loud fan noise, but noticeable even more as soon as it hits 1500 rpm, at that point it sounds like a grinding of a bearing almost. It seems to come from the fan itself, the a/c, alternator, and power steering pulleys all seem to be fine. Replacing the belt tensioner assembly got rid of the whine part of the noise but not the more annoying kind of grinding noise. I do know that the fan is in failed mode, but so far it is keeping the engine at temperature instead of cooler, could that be why I don't have a CEL?

[Opeth]

I had something similar I believe go on not too long ago, I replaced both tensioner and idler pulley and one of those resolved the problem.... Or both.... 90k miles on OEMs so they needed to be done anyway.

[RyansTBLS]

So I checked the idler pulley, and ick, it looks almost as bad as the belt tensioner. Both were obviously original and she's got over 103,000 miles on her. I'll replace that next, still don't know why the fan always has to be on. But I'll see if the idler pulley fixes the sound at least.

[The Roadie]

What makes you think the fan is on? If it's merely spinning around at idle, of course there's residual friction in the bearings and the working fluid. You can normally stop that with a rag pressed against the edge. If it's being commanded on, or if the internals are really gooey, then you can't stop it with external friction and THAT'S what causes unexpected audible noise.

[RyansTBLS]

Ok, so that's making a bit more sense to me now. So here's another question, the truck used to with the truck off the fan have very little play in it, a quarter inch or so either way, now it can move all the way around. Is that something I should be concerned about? I miss the old straight up mechanical stuff...

[djthumper]

If you mean that you had about a 1/4" of rotation and that you can rotate it further you are fine. You should be able to rotate the fan when the clutch is disengaged.

If you had a 1/4" of play in the fan I would replace the clutch and probably the water pump due to wear. From the way you said things I am guessing that you mean the previous statement.

[RyansTBLS]

yea I meant the previous statement, sorry about that
ok so fan seems to be good, sure hope the noise is the idler pulley

[RyansTBLS]

argh
So I replaced the Idler pulley, and that helped that noise, but then I noticed the steering pump pulley was making a racket, so I replaced that as well. Now that all of that is silent, it is definitely coming from the fan clutch. The acoustics in the engine are horrible Just to confirm that it was the fan clutch, the truck has started throwing the P0495 code. Can't tell why I didn't get the code before I replaced everything, but with as worn as everything was maybe the belt wasn't as tight as it should be just guessing on that. But looks like I need a new fan clutch now. The question is should I just replace the E/v with another E/v, or got the mechanical route? Though admittedly since this is the original E/V clutch at 103k miles, tempting to just go back to the same.

[DirtyBacon04]

go with the original part. if you start trying to change the way your cooling system works, then your headaches are far from over.

also, i can't remember. did you replace your water pump yet?

[RyansTBLS]

That got done at about 70k miles, that wouldn't give a P0495 though would it?

[RyansTBLS]

a couple installation videos, for anyone else who gets to do this

[RyansTBLS]

Thanks for fixing the links!

So I did this today, not too big of a problem. Though I made a heck of a mess disconnecting the radiator hose.
It would have taken me a little less time and a lot less energy if I had been trying to turn the nut counter-clockwise. Not sure if all trailblazers turn that way but I would assume so. So when I did get it off it was on really tight for some reason....

I will post up when I take her for a drive tomorrow, but so far just running her she sounds great of course after the last three time she sounded better too....

Hopefully anyone else with engine noise, whirring, grinding, clicking and other weird noises finds this thread, since I've done most of the rpm noise stuff so far.

[The Roadie]

There are no backwards threads anywhere in the vehicle.

[Trail X]

The rear diff ring gear is left hand threaded.

[boog2006]

Bazinga

[RyansTBLS]

So after putting 2000 miles on the fan clutch, the strange little noise returned and got louder, in addition a kind of vibration was added. Long story short, the water pump has not been replaced with the metal gasket. Also replaced the water pump pulley since I was in there anyways, so far so good. At least the engine is quiet again.....