Fan Duty Cycle
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Senior User
Joined: May 2007
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From: Central Texas
Fan Duty Cycle
After having to change out my Radiator due to a cracked tank, flushing the system , and new termastate, I have been using my AE software to monitor my ECT EOT and Fan speed.
Yesterday I pulled a 5k load 300mi in 100+ outside temps In the hill country of Texas.
My EOTs always seem to run 8 - 12 deg of ECT
Max temps i saw was ECT 225 EOT 235 and this has me very concerned
My fan comes on at 221 and kicks out at 217 and never exceeds 60% of Engine RPMs
With the AE software I can command the Fan duty cycle to 100% and the fan speed will exceed the Engine RPM.
I dont understand why my fan will not kick in at a lower ECT and why the duty cycle will not go higher as the ECT rises.
Any ideals why my fan is acting this way?
Yesterday I pulled a 5k load 300mi in 100+ outside temps In the hill country of Texas.
My EOTs always seem to run 8 - 12 deg of ECT
Max temps i saw was ECT 225 EOT 235 and this has me very concerned
My fan comes on at 221 and kicks out at 217 and never exceeds 60% of Engine RPMs
With the AE software I can command the Fan duty cycle to 100% and the fan speed will exceed the Engine RPM.
I dont understand why my fan will not kick in at a lower ECT and why the duty cycle will not go higher as the ECT rises.
Any ideals why my fan is acting this way?
Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 25
From: Middle Tn.
There are multiple things that control the fan speed through the pcm. Your temp. readings for cycling appear normal to me. The t-stat normally is not fully open till around 217. I also have my doubts about the fan speed being higher than the engine rpm's. I can't run faster than my legs can move. Think about that one. Otherwise the fan could drive the engine so to speak.
Lead Driver
Joined: Sep 2007
Posts: 8,180
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From: Scio, OR
The fan/water pump pulley is smaller than the crank pulley, so at 100% fan, it will be going faster that the engine RPM. As to why the truck is not commanding the fan higher, I don't know. Your temps don't seem out of line to me. I suspect if the temps went higher, the fan duty cycle would go higher as necessary. The thermostat doesn't fully open until 219, so I don't thing 225 is excessive. I don't think I'd want it much higher than that, though.
Lead Driver
Joined: Feb 2011
Posts: 8,241
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From: L.A. (Lower Alabama)
I can't help much except to sympathize with your concern. I towed our 10k fifthwheel a couple hours over the 4th weekend and saw almost identical temps. I didn't think monitor the fan but I did hear it cycling. My unloaded temps and delta are the same also. I've read everything from "keep an eye on it" to "park it before blows up" so I'm not sure how concerned to be. With everything in speck with the TSB as far as I can tell. I think I'm ok unloaded but need to resolve this before my next tow. In the Tech folder thread about temps and pressure there is some discussion about what conditions determine fan duty cycle and how the fan "clutch" works. Might give you some insight.
Last edited by Rusty Axlerod; Jul 10, 2011 at 09:28 AM. Reason: Cellphone buttons too small/fingers too big
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Senior User
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From: Central Texas
I have my doubts on the fan speed exceeding rpm also but others have reported the same results wth their AE software. At 100% duty cyle and 2000rmp the AE will report fan speed sligtly highter than rpm
Are you saying that these temps are normal? I often read in the threads about much lower temps and fans that kick in at 215 keeping the temps lower.
Are you saying that these temps are normal? I often read in the threads about much lower temps and fans that kick in at 215 keeping the temps lower.
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Senior User
Joined: May 2007
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From: Central Texas
My biggest concern is that the last few loads have been small (5k). I have recently bought a 11k 5er but have not made a trip with it yet. Befor I did the rad and flush I pulled the 5er about 20 mi and seen temps at 230. I dont want to see my temps go sky high and end up with a major problem.
At what temps does the engin start to defuel and what is the max temp this engin can go without damage?
At what temps does the engin start to defuel and what is the max temp this engin can go without damage?
Lead Driver
Joined: Feb 2011
Posts: 8,241
Likes: 155
From: L.A. (Lower Alabama)
I would think it could if the fan pulley is smaller diamerter than the crank pulley. I don't know if it is tho.
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Senior User
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From: Central Texas
I can't help much except to sympathize with your concern. I towed our 10k fifthwheel a couple hours over the 4th weekend and saw almost identical temps. I didn't think monitor the fan but I did hear it cycling. My unloaded temps and delta are the same also. I've read everything from "keep an eye on it" to "park it before blows up" so I'm not sure how concerned to be. With everything in speck with the TSB as far as I can tell. I think I'm ok unloaded but need to resolve this before my next tow. In the Tech folder thread about temps and pressure there is some discussion about what conditions determine fan duty cycle and how the fan "clutch" works. Might give you some insight.
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Lead Driver
Joined: Feb 2011
Posts: 8,241
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From: L.A. (Lower Alabama)
According to the Tech folder (thanks bismic!):
https://www.ford-trucks.com/forums/s...d.php?t=974357
Engine defuels @ 221 ECT and 253 EOT.
Engine def
https://www.ford-trucks.com/forums/s...d.php?t=974357
Engine defuels @ 221 ECT and 253 EOT.
Engine def
Lead Driver
Joined: Feb 2011
Posts: 8,241
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From: L.A. (Lower Alabama)
Yup, I was referencing you 8-12 degree spread. That's after I top a hill and start down the other side. The EOT lags behind the the ECT a good bit. I have seen 217 ECT unloaded.
Lead Driver
Joined: Feb 2011
Posts: 8,241
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From: L.A. (Lower Alabama)
You may be on to something with the fan business. I've read at least one of the HP tunes disabled the fan so that makes me think it would be addressable via the software. Maybe some of the tow tunes could (or do) lower temps some by turning on the fan sooner?
Allowing the oil temp to get to 253 before beginning to defuel makes me think maybe we are ok at 235 but at what temp does oil start to break down or scorch or whatever and, if it's at 235 at the temp sensor it's likely a lot hotter in the turbo bearings. I'm using Motorcraft 15w-40 (hell, it's got the powerstroke logo right on the jug) but thinking of synthetic now.
Allowing the oil temp to get to 253 before beginning to defuel makes me think maybe we are ok at 235 but at what temp does oil start to break down or scorch or whatever and, if it's at 235 at the temp sensor it's likely a lot hotter in the turbo bearings. I'm using Motorcraft 15w-40 (hell, it's got the powerstroke logo right on the jug) but thinking of synthetic now.
Lead Driver
Joined: Feb 2011
Posts: 8,241
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From: L.A. (Lower Alabama)
"begins to defuel" may not be very noticeable on a diesel. Maybe somebody more knowledgeable will chime in here. I do know more fuel makes it hotter while on a gasser a rich mixture is cooler. Another possibility is that info is for a different flash than your truck is running.
Postmaster
Joined: Jan 2005
Posts: 4,424
Likes: 12
From: BC Canada
Those sound like normal water temps for the fan control steps. The third step is for towing and heavy work pulling hills. I watch my outlook monitor and doubt without pulling you will ever see third stage actually come on. Rare very hot days. You have a lot of cooling capacity and are needeingit at those temps.
Posting Guru
Joined: Oct 2010
Posts: 1,192
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From: Kerrville, Tx
im in the same boat as you. im trying to figure out why my brothers temps are so high while towing our bay boat. but on my truck i stay at 210 and the fan kicks on at 210. on my bros the fan wont kick in until 225-230 and those temps have me worried! im going to get the newest flash here in the next week or so and see if that helps because he still has the 04 tune from the factory on there. maybe the updated tune will lower the ECT and kick the fan on sooner.