Hello,

I have a 2004 trailblazer 4.2L with 50K miles.
While pulling my boat a few weeks ago I noticed the engine temp ran up to 240 deg normally it runs a tick below 210. Outside temp was 87. When not pulling the boat on hot days the engine temp runs normal with AC on.
I noticed the fan never really engaged at all. It spins slowly and I can stop it with my hand. So I replaced the fan clutch that I received from 1A auto, now the fan is engaged all the time even at normal engine temp. GM deal told me to unplug the fan plug to see if it disengages and it does when I drive down the road. As soon as I plug the fan back in it engages fully. I drove it for a few miles and it never disengages. I never received a check engine light. I had the thermostat replaced last year. The coolant temp sensor is original. I swapped the 45,46 relays and checked the fan fuse all good to go. I also unplugged the battery. Any ideas?

This has an electronic fan clutch. The fan is supposed to freewheel all the time unless engaged.

How big of a boat? . . . or more importantly: how much does it weigh?

When it got hot, were you going up a hill?

If "yes", for how long?

What were the RPMs at?

ITs a 17'10" ranger bass boat around 2800lbs. The temperature was steady between 230-240 on flat ground or hills. Rpm were never over 4500.

I'm not sure, but the fan clutch could freewheel at higher RPMs. Maybe one of the guys knows this with more certainty.

It sounds like not too heavy of a boat. It is a bit of extra air to push and rolling resistance to overcome. When climbing a hill, does the temperature maintain itself at 230-240 or does it climb higher as you climb the hill?