Easy way to tell when fan is running while driving

[Rick Rae]

Originally Posted by Diesel_Dave

Does anybody know whether a Scangauge will give you the fan speed?

The Scangauge is capable of displaying pretty much anything available via OBD II (though manufacturer-specific stuff can take a little effort).

But there's the rub: it has to be available, and I doubt fan speed is. There'd have to be some sort of sensor on the fan. I've never seen that.

Cheers,
Rick

[Diesel_Dave]

Originally Posted by Rick Rae

The Scangauge is capable of displaying pretty much anything available via OBD II (though manufacturer-specific stuff can take a little effort).

But there's the rub: it has to be available, and I doubt fan speed is. There'd have to be some sort of sensor on the fan. I've never seen that.

Cheers,
Rick

I believe my truck does have a fan speed sensor. I found some info over at the Cummins forum where somebody posted the diagnotic procedure to check and see if the clutch is working properly and it involves the technician hooking up a diagnistic tool and reading the fan speed and different engine rpms, so I take it it is and OBD II parameter.

[Diesel_Dave]

On another note I played around with the fan a little yesterday. After work I went out (with the engine cold), popped the hood and started up the engine. The fan came on immediately, but then went off after 1 min or so. That's a good sign. One of my concerns was that my fan was on in the first few miles of cold start, hurting my warm up times.

My understanding is comes on initially to move the fluid around where it needs to be and then turns off untill things get hot. If that's the case, then the first minute may be all that my fan ever runs during normal commuting. Even with my block heater, it still takes me ~7mi to get up to 200 F coolant temp on cool mornings.

[dcb]

Originally Posted by Diesel_Dave

...
From a FE standpoint a clutched mechanical fan is superior to a pure electric fan because you don't have all the losses associated with the alternater converting mechanical power to electrical power and then an electrical motor converting electrical back to mechanical...

This is probably a wash when you consider you can shroud an electric fan to a radiator with much closer tolerances (it isn't bolted to a big bouncy engine). So the air an electric fan moves goes more towards cooling. It also doesn't require a separate belt and associated weight/losses there.

The most efficient cooling air uses your forward motion (with appropriately sized openings for the current airflow demands), but for occasions where you need to force air over your radiator an electric fan isn't a bad choice.

[Rick Rae]

Originally Posted by Diesel_Dave

I believe my truck does have a fan speed sensor... hooking up a diagnistic tool and reading the fan speed and different engine rpms, so I take it it is and OBD II parameter.

Awesome! Then you can probably read it. Scangauge's current firmware supports "X-Gauges" which are basically "roll your own." It might take some digging to find the right command(s) to send the ECU, but once you add them you should be good to go!

Cheers,
Rick

[Diesel_Dave]

Another reason for me to cough up the money for a Scangauge

[Rick Rae]

Originally Posted by Diesel_Dave

Another reason for me to cough up the money for a Scangauge

In my experience, once you get used to having one you'll wonder how you managed to "drive blind" for so long!

Rick

P.S. In the interests of full disclosure: Some people say they've learned all they can and have sold their Scangauges. So, YMMV!

[Diesel_Dave]

Okay, so the other day I confirmed that my fan is off virtually all the time.

I recently put in a full radiator block (in addition to my upper grill block). I had turned back kind of warm that day (70's) and I had to go make a trip on the interstate. P&G'ing between 55-65 ish after a while I started to hear this wierd sound at the beginning of my pulses. After a while I figured out it was the fan kicking on.

Guess that confirms how oversized my engine is--when I have to block off the whole radiator and then drive it "hard" to get the fan to kick on--and then only occasionally.

[slowmover]

No, how oversized is the cooling system for non-paid/non-working miles.

[Diesel_Dave]

Originally Posted by slowmover

No, how oversized is the cooling system for non-paid/non-working miles.

Or, how oversized the whole truck is for just hauling my fat butt around