Under normal driving, my cooling fan rarely comes on. The truck runs ECT 194 to 200 and EOT about 7-8 degrees warmer. On grades in the mountains, not towing, it will cycle on if the ECT gets to 210, cools it down and cycles again if needed. My question is, under similar conditions, what does your truck do? When towing my 5th wheel, about 13k, when its 90 degrees plus, at between 60 and 65mph on level ground, my ECT runs 210 and the fan comes on to around 1400rpm and cools it back down to about 204. When the ECT gets back to 210, the fan does the same. On uphill grades, I see as much as 220 ECT. When this happens the fan comes on at around 2500rpm and cools it down to about 199 pretty quickly. I have a new oil cooler so my oil always follows and on my last trip I never saw more than EOT of 225 on the longest, steepest grade. The reason I ask is to see if this seems normal. My mech keeps mentioning that if my fan is cycling it may be head gaskets. But, I don't have any other head gasket symptoms. I think it seems pretty normal. If the fan doesn't come on and cool the engine when its working this hard, then what is it for? What does your truck do under similar conditions?

 

I think what your fan is doing is VERY NORMAL. My truck is very very similar. I'd be very concerned if your fan DIDN"T come on exactly as you described.

 

completely normal. Mine is the same way. fan comes on at 210, cools it back down pretty quick.

Sounds like your cooling system is acting exactly how it should, especially for towing that kind of weight.

 

That's what I'm thinking. When yours comes on and cools it back down and the fan goes back to about 400rpm, how long is it before the ECT gets back to 210? I am having the A/C problem I discussed in a previous thread that happens while towing, which is new. And the jerking/bucking deal when towing, which is new. But the fan has always cycled like that for the 7 years I have been towing with the truck.

 

If you want to scroll through this track log I did with Torque APP, it will give you an idea of How mine ran while towing.

ECT, EOT, TFT, Fan speed, Boost, IAT2, IAT1, ICP, IPR, RPM, altitude and speed.

It's not laid out real well, but you get the idea.

Highest Fan Speed reached 3601 RPMs.

 

That is very similar to mine. I'm using Torque also. I need to set it to log next time I tow. It looks like your fan is coming on at 210.2 and running about the same rpm as mine. I think I am far from needed head studs and gaskets.

 

bumping older thread on this.

i am seeing fss at 400-525 rpm. does not vary with engine speed or temp. ect 195-200 towing 5k box trailer on flat ay 60mph. on slight rises or under power, temp went up to 213 or so. again, no change in fss, stays at 400-525rpm.

based on the detail in this thread and others, it seems there should be some reaction from the fan clutch. i can recall in the past rarely seeing ect over 200, if it got there, could hear the roar of the fan come on and bring temp right back down. (at the time i did not realize the scan gauge could pull fan speed)

am i being paranoid?

 

You're being paranoid.

Josh

 

Yep I've only heard my fan a couple of times and only checked the FSS a few. It will only ramp up when it's needed

 

thanks.
Ran it some more on hotter day yesterday with 5k lb box trailer. At 170TFT, 90 IAT and 218 ECT, the fan spun up to 1200rpm. Temp got up to 222 ECT max. I guess this is the new normal compared to what I was seeing before (early fan spin up and temps below 210 all the time).

 

As an FYI the fan is turned off at speeds over 50 mph until the ECT reaches about 218-221.

If you're at 218 @ 60 mph, I would reckon the fan will ramp up if you slow down to 45-50 mph.

The fan behavior is quite a bit different with A/C on versus switched off too, especially in city driving.

Josh

 

thanks for the info Josh.