Radiator and HD clutch are about a year and a half old. Nissens radiator. I think it's the clutch. We will see soon...

 

My Viscous Fan Clutch SEEMS fine... but how do I really know? If it's starting to fail... is it not spinning while in traffic... or is it somehow weaker and not pulling/pushing enough air?

 

 

OK... I've got an update...

Drove to the office (5.25 miles) yesterday... outside temps were in the low/mid 60s. Temp on the UG got up to 201 at one point. When I had my foot on the gas and moving temps went back down to 195 to 197.

I replaced the Viscous fan last night and drove in to the office this morning. Temp didn't get above 194 and was mostly around 188 or even lower for the majority of the ride... with similar outside temps.

Now I have a question. Why have a viscous fan anyhow? Why isn't it just fixed (always spinning 100%) like my old jeep? Cold climates?

 

I replaced my Hayden HD clutch two days ago. I had the same temps and same result! The clutch was plenty viscous hot and cold. I couldn't spin it more than half a turn by hand. I can only assume the thermostatic spring on the front of the clutch had failed and it was not engaging fully. Very strange. The HD clutch should have lasted more than a year and a half.

 

Mostly fuel economy, it reduces engine load. there are a few other benefits but they are mostly kinda of vague.

 

So essentially the lower temps brought the viscous fan issue to light since the condenser fan doesn't run in cooler temps.

Anyone know what temp the viscous clutch should engage dissengad?

 

I believe the aux fan not running and not really being cold enough out to crank the heat, thus also cooling the system, is what brought the issue to light. The new HD clutch seems to have been the easy fix. Again, my fan was plenty viscous hot and cold. It did not freewheel at all by hand.

 

They vary but do not really fully disengage, How thermal Fan clutches work as to temp most engage at about 170° - 190 radiator air temperature, (about 30° lower than coolant temperature). But the best bet is to check the specs for the one you have

 

Yes... I echo what "dtmbinb" said. Basically the same situation... truck started running hot and my fan/clutch felt like it should when pushed, but apparently just wasn't working enough. Tonight, with low 50's temps I didn't get above 187.