Pulsing under load
It's a Van Gogh
Joined: Feb 2010
Posts: 7,813
Likes: 1,335
From: Elk Grove, CA
Ah that sounds like the fan clutch engaging. It will cycle on and off in a very steady way, with an interval of 2 seconds or so. The clutch is mechanical, not electric. The fan sound is pretty loud when on and you can feel the power dip slightly as the fan steals power that otherwise makes the truck go. Only happens when hot and working hard. I owned my truck for a long time before I heard it.
If that's it, it's normal operation.
If that's it, it's normal operation.
Cross-Country
Joined: Oct 2013
Posts: 51
Likes: 0
From: Eastern Washington State
Ah that sounds like the fan clutch engaging. It will cycle on and off in a very steady way, with an interval of 2 seconds or so. The clutch is mechanical, not electric. The fan sound is pretty loud when on and you can feel the power dip slightly as the fan steals power that otherwise makes the truck go. Only happens when hot and working hard. I owned my truck for a long time before I heard it.
If that's it, it's normal operation.
If that's it, it's normal operation.
Thanks.
It's a Van Gogh
Joined: Feb 2010
Posts: 7,813
Likes: 1,335
From: Elk Grove, CA
Same here! The sound was so regular that my brain went straight to PCM control, when it was in fact simply mechanical.
On the plus side it demonstrates the efficacy of the OEM set up. When that big **** fan hits it makes a difference and solves the problem!
On the plus side it demonstrates the efficacy of the OEM set up. When that big **** fan hits it makes a difference and solves the problem!
Cargo Master
Joined: Sep 2015
Posts: 2,860
Likes: 365
Ah that sounds like the fan clutch engaging. It will cycle on and off in a very steady way, with an interval of 2 seconds or so. The clutch is mechanical, not electric. The fan sound is pretty loud when on and you can feel the power dip slightly as the fan steals power that otherwise makes the truck go. Only happens when hot and working hard. I owned my truck for a long time before I heard it.
If that's it, it's normal operation.
If that's it, it's normal operation.
It's a Van Gogh
Joined: Feb 2010
Posts: 7,813
Likes: 1,335
From: Elk Grove, CA
@jstihl sorry I don't know the temp when the clutch engages. When I've seen it air temps are 90's and up. There's some sort of goo inside it, maybe a silicone, not really oil. As for jet engine noises that makes me think of the EBPV, the fan just sounds like a fan to me. The pulsing is weird tho. I suppose if it got hotter it would engage full time but I've not seen that.
Got Data?
Joined: Dec 2012
Posts: 4,260
Likes: 1,390
From: Lake Stevens, WA
Some interesting discussion from "AutoJim, Former Cooling Guy" in this thread about engine coolant temp, radiator air temp and fan operation here:
https://www.thedieselstop.com/thread...kick-in.53733/
https://www.thedieselstop.com/thread...kick-in.53733/
Thread
Thread Starter
Forum
Replies
Last Post
ddetar00
6.7L Power Stroke Diesel
17
Jul 8, 2011 10:32 AM
countrydoc
1987 - 1996 F150 & Larger F-Series Trucks
15
Aug 4, 2007 02:16 PM
