Fan noise only in reverse - Chevy and GMC Duramax Diesel Forum
06-07 LBZ & LLY Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

  • 1 Post By clemet
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post #1 of 3 (permalink) Old 11-14-2019, 06:37 AM Thread Starter
Join Date: Sep 2014
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Fan noise only in reverse

So I will try to explain this as best I can. About 2 weeks ago I got home and heard a bad idler pulley and after I replaced it I was getting a really strange noise almost sounding like the fan hitting the shroud/guard, but it stopped almost right away and didn't come back until yesterday. I was backing my trailer in and when I use any power over idle it is making this loud shrieking sound. I crawled under and noticed the motor mounts where trashed so I swapped them out yesterday with rubber ones from the local parts house. The passenger side one was completely trashed, and the driver side I was able to finish pulling apart by hand. After I was done I checked it and it is still making the same noise. I have checked that the shroud is bolted down tight. I cannot make it make the noise in anything other than reverse, and only if the engine is off idle.

Here is a link to a video with the noise.

I am just sitting here scratching my head as to what else I need to check since it is only in reverse unless I received a bad mount and need to swap out the driver side again.
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post #2 of 3 (permalink) Old 11-14-2019, 05:48 PM Thread Starter
Join Date: Sep 2014
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I found the issue to be the bolt around the fan surround under the air cleaner was missing. All is fixed now.
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post #3 of 3 (permalink) Old 11-14-2019, 10:17 PM
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Join Date: Dec 2018
Location: Decatur, AL
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Thanks for closing the loop on this. It was classic symptom of motor mounts.

2019 Silverado 2500 4WD, Cajun Red
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