Should my fan be running on start up?

[Lanskpr]

Reading about the cooling system of the 6.5's I understand the fan clutch will engage at a certain temperature to aid in cooling. Does that mean that the fan will not turn until that point?

[DmaxMaverick]

It's normal, as long as it tames down after a few minutes, depending on the outside temp, how long it's been cold-soaking, how long it idles cold, and other minor factors. Settled cold fluid inside the clutch takes a bit to distribute and warm. The fan clutch should engage at higher temps, as the thermostat(s) open. The higher coolant temp in the radiator (and subsequent hot air from it) is what engages the fan when hot.

[Lanskpr]

It's normal, as long as it tames down after a few minutes, depending on the outside temp, how long it's been cold-soaking, how long it idles cold, and other minor factors. Settled cold fluid inside the clutch takes a bit to distribute and warm. The fan clutch should engage at higher temps, as the thermostat(s) open. The higher coolant temp in the radiator (and subsequent hot air from it) is what engages the fan when hot.

Thanks Dmax !
I will run the truck tomorrow paying attention to what happens after startup. I usually let it warm up for 10 minutes or so since it will be in the low teens overnight. My plan is to drive it and stop and check it during it's run. During cold days, I will be lucky to see the temp gage reach within two hack marks from 210 f mark. During the summer the gages holds right at 210 f except on hot days and especially if its loaded. Then it may creep a hack above 210 f for a minute or so and then drops below 210 f.

This interest in cooling is due inpart to what I have been reading here. Concerned about engine life and the fact that I go through a lot of PMDS. The last one(gray version) lasted about a year. However, while changing it out found that all 4 mounting screws were barely snug. Pretty sure that caused its demise. I usually get a couple of years out of them, at the least. It still functions and I will keep it as a spare. Or, if the new PMD doesn't stop the stall/hiccup, I will keep the new one as a backup and re=install the old one. Something like that.


So, I am looking into cooling up grades. Not sure to what extent, though. Certainly will start with cleaning the radiator fins throughly. Looking at the calibrated Fan Clutch and upgraded fan as the first up grades. The system is filled with a "Dex-cool" mix that my local mechanic did at 180000 miles in 2006.(Water pump was replaced then also) Is it recommended to continue using Dex-cool? Any other thoughts /opinions are greatly appreciated, And, of course everyone is welcome to chime in!

[DmaxMaverick]

Don't sweat it so much, so to speak, when it gets that cold. It takes longer for the fluid in the clutch to warm up and get distributed. Often, it may not free up until the engine operating temp gets up, or you have and extended run. Idling does very little to help it along.

Yes. Stick with the Dex-Cool. If you have issues with it, the problem isn't the coolant. Something else needs to be fixed. Good idea to get the cooling stack cleaned up. That never hurts. A good fan clutch, like Kennedy's, is an excellent upgrade (all others, regardless of claims, are OEM spec or less). Your original fan should be fine. If you have an early 96 truck, an upgrade to dual stats and HO water pump is an option. That pretty much covers the cooling system. If your truck already has dual stats, cleaning the stack, installing good stats (Robert Shaw) and adding the Kennedy clutch is about all you can do, or want to, for improvements.

[Lanskpr]

Don't sweat it so much, so to speak, when it gets that cold. It takes longer for the fluid in the clutch to warm up and get distributed. Often, it may not free up until the engine operating temp gets up, or you have and extended run. Idling does very little to help it along.

Yes. Stick with the Dex-Cool. If you have issues with it, the problem isn't the coolant. Something else needs to be fixed. Good idea to get the cooling stack cleaned up. That never hurts. A good fan clutch, like Kennedy's, is an excellent upgrade (all others, regardless of claims, are OEM spec or less). Your original fan should be fine. If you have an early 96 truck, an upgrade to dual stats and HO water pump is an option. That pretty much covers the cooling system. If your truck already has dual stats, cleaning the stack, installing good stats (Robert Shaw) and adding the Kennedy clutch is about all you can do, or want to, for improvements.

Thank you for your insight. I am going to clean and do the fan clutch this year and do the dual stats next year. Thanks again.