Derale Electric fan knocking at start-up
Thread Starter
Instructor
Joined: Apr 2009
Posts: 126
Likes: 54
From: LA CA
Derale Electric fan knocking at start-up
I have not had time to tear into this yet. But, my Derale electric fan is starting to knock, multiple times and real loud, when the thermostat temp relay tuns it on. Once on it works fine. I used to hear just a slight click when driving. It let me know the fan was turning on. Now I am getting three to four loud knocks before the fan turns on and then it works fine, nice and quite. I have the temp relay set for about 160 deg. It is cooling a 454 w/ A/C. The fan can keep it between 190 to 200 deg. even in traffic.
I was going to direct wire the fan to the battery to try to determine if it is the relay or is the fan going. Just looking to see if anybody else has dealt with this.
I was going to direct wire the fan to the battery to try to determine if it is the relay or is the fan going. Just looking to see if anybody else has dealt with this.
Safety Car
Joined: Dec 2012
Posts: 3,800
Likes: 1,712
From: Summerville SC
check to see if a blade is bent and hitting something. I had that issue on a car once exactly as you described. Once it ran a little it was fine. It ended up the temp heated up either the fan or the shroud and the noise would stop. It ended up being a bent blade.
Race Director
Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
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I'd say, spin that blade by hand with everything turned off. Any knocking? I had one with a bad bearing. It didn't end well.
Le Mans Master
Joined: May 2007
Posts: 5,019
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From: North tonawanda NY
In my case the fan spun fine by hand but when it was powered on the inertia of it starting caused it to momentarily shift and make a noise. one of the plastic spokes that holds the motor was cracked.
Thread Starter
Instructor
Joined: Apr 2009
Posts: 126
Likes: 54
From: LA CA
augidoggie, my man, you are the winner! When I went down to garage ooozing with testosterone, hot coffee, and my trouble shooting matrix going through my mind, the first thing I discovered was the upper, right fan mounting bolt was missing. As you described, the fan mount must have been smacking the shroud at start-up. I replaced the bolt and my nice quite fan was back.
Thanks for the responses
Dins74
Thanks for the responses
Dins74
