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Mechanical Fan Contacting

DBenz

DBenz

NAXJA Forum User
Location
Manhattan, Kansas
Hey guys,

I replaced my serpentine belt last week because the old one was starting to crack and stretch. Soon after this, I'm getting a harsh metal on metal sound coming from the front of the Jeep. It's primarily when I turn right and will continue to do so for a bit after the initial contact. It sounds like the fan is catching something like a pulley (found a small wear spot on the crank shaft pulley. It will even continue to do so after the Jeep is shut off, as the fan is slowing down. The bolts are not loose on it at all.

It won't do it when I start it up and look under the hood, only while driving. Any ideas on why there is contact being made and how to fix it? The noise is god awful and really worries me. I had searched a little and some said motor mounts should be checked in case the engine is **** eyed in the bay, but it's got Brown dog offroad motor mounts on it. Maybe transmission mount? Thanks for any and all leads,

Derek
 
Did you loosen the radiator when you changed the belt? If so, did you get it back in place correctly?

What is the condition of your engine mounts?
 
Did not loosen the radiator, only tensioner bolt and pulley bolt. Motor mounts appear fine, aren't they supposed to be bullet proof?
 
The mounts, yes, but the rubber or nylon bushings wear, and the plates that mount to the engine where the engine mounts attach like to break their bolts.

Check the balancer on the crank--maybe it is separating and "walking".
 
Last edited:
From your description of the noise; it sounds like the harmonic balancer is separating which is allowing the pulley to contact the timing chain cover.
Use a bright light and shine it at the pulley to see if there is evidence of the pulley rubbing. Probably can see this better from under the vehicle; assuming the protective engine mat has been removed.
If this is the case; you should consider not driving the vehicle until you replace the harmonic balancer. When it lets go while driving; it WILL cause a lot of damage (fan, radiator, shroud, etc....).
 
I forgot to set the lower tabs on the fan shroud once ... made one hell of a racket when I was driving and even more so when I got on it
 
First find where the contact is.. if its doing it after the engine is shut off it shouldn't be too hard to find by rotating the fan by hand. Since you mentioned a wear spot on the crank shaft pulley I would concentrate in that area.
 
It looks like there's wear marks on the harmonic balancer, I was not sure what it was called. When my serpentine belt broke, it was a strip taken off the entire length of the belt, leaving it intact but too thin to cover the pulleys. Once that piece came off, it wrapped around the fan.

I get consistant squeaks from the belt and the fan contact is getting more severe. I've parked the heep and have Friday off to investigate the issue. Thanks for the input
 
DBenz said:
It sounds like the fan is catching something like a pulley (found a small wear spot on the crank shaft pulley. It will even continue to do so after the Jeep is shut off, as the fan is slowing down.
Derek
Click to expand...

After rereading the OP I realized my response probably doesn't hold water.
The only component that continues to spin for a short time after the engine has stopped would be the thermostatic clutch.
 
Wear marks on the harmonic balancer as if it's sliding forward into the mechanical fan. Does the balancer need replaced? Maybe a seal gave out and that may have caused the serpentine belt to fray.
 
are you sure its not catching the radiator? My motor mounts are worn out and was catching my radiator when i drive up a large ledge or rock because of the torque. (they are being replaced obviously)
 
I'll check them out tomorrow. I can see when the stock MM are worn out because the bushings were torn in several places. These brown dog offroad mounts are only about 2 years old. Maybe my transmission mount is out because it wasn't replaced when the motor mounts were swapped.
 
It would also makes sense about the large ledge, as the place that I just moved into is at the top of a very large, steep hill and this is when it does it the most.
 
DBenz said:
Wear marks on the harmonic balancer as if it's sliding forward into the mechanical fan. Does the balancer need replaced? Maybe a seal gave out and that may have caused the serpentine belt to fray.
Click to expand...

Yes, sounds like balancer is starting to walk forward.

Balancer is coming apart, don't run it or you'll have more problems if it flies apart.

3
 
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