I've got an 08 srw f350 quad cab with 113k on her. DPF delete.

My wife drives it. I maintain it. When she rolled into the garage the other day, she shut it down and I heard a slow rotational "Warbling" sound as if the fan was slowing down to a stop.

Popped the hood and inspected everything. It's levels are all good and clean, the mechanical wiggle test proved nothing to be loose.

I had her fire it up and shut it down with my head and eyes nervously watching and it is matched to the fan slowing to a stop.

I've read a lot on this forum and I'm leaning toward a fan clutch problem although I can spin it at will and not get the noise, or am I looking at possibly a water pump issue.

The noise matches the fan rotational speed as it slows and as far as I know, the water pump is not rotating if the engine has already shut down.

All gauges and lights are normal.

About the only real way to see if it is the fan, is to remove it and see if the warble disappears after shut down.

Make sense or should I be looking at something else??

Highest regards.

Denny

 

Can't say what it might be. I know I can hear the turbos wind down sometimes when I shut it off. As far as the fan clutch goes, if it's tight, and you can't duplicate the sound turning it by hand, I would be looking somewhere else. Could something be touching the fan?

 

Could it be the heater fan? Even turned off, I believe it runs all the time.

 

I'll go back out and check for interference and isolate the exact locale.

Btw John, I used to run the rivers for the Coast Guard putting in Buoys. Fun job!!

Denny

 

Really! I assume those were to mark the depth for traffic. That picture you see in my avitar is the Ferry at Augusta, KY going across the Ohio River to Ohio.

 

My 08 has done that since day 1. I always thought it was the turbo decompressing. I have had no issues from it.

 

Brada. Any coolant leak history, how is your temp gauge?

I can't nail this and I ain't a spring chicken, but it seems to me it is in the fan revs coming to a slow stop after shutdown.

Checked for ANY interference. None. Fan spins nice and quiet in both directions.

John, it is definitely isolated to the fan.

Thinking I am going to pull the fan and check the assembly independent of the truck to see what the mystery noise it's emitting is.

Could be the bearing????!!!

Denny

 

4x4? If it is could be the vacuum pump and you have a vacuum leak. If you have a leak turn the key on, don't start it you will hear electric pump running, provided the system is low it will run.

 

Dieseldenny, no, I have never had any issues with my truck, 78,000 miles and nothing! The sound is sort of like a low frequency horn when the engine is stopping. I just put on a new belt and that did not change anything. Belt Tensioners all good too. My old dodge did a screech when shut down and my 2008 ford just the horn, or whoop whoop sound, never worried about it.