1999 LX470 Fan wobble/chirp (1 Viewer)

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1999 LX470 - 173k miles

My engine has a whirring and constant chirping sound associated with rpms in the 2k and above range. The whirring gets louder as the rpms increase.

When I remove the serpentine belt and run the engine in the 2k plus rpm range the whirring sound does not exist. The chirp does not exist when the engine is run without the serp. belt.

I just replaced the serpentine belt tensioner pulley bearing and the serp. belt idler pulley. New belt coming Friday. New ATF fluid for a Power Steering fluid flush but there is plenty of fluid in there now.

I noticed the fan seems to wobble a little and the chirp sounds like it may be coming from the fan clutch/fan bracket area.

Does the fan clutch have a bearing that goes bad or would this wobble come from the bracket? Im getting close to needing another timing belt job (done at 88k, mileage is 173k now) so if it is the bracket Im thinking I may just do the timing belt/water pump and replace the fan bracket as well.

 
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I am in the same boat as you, replaced all bad pulleys and still get a chirp at idle. I'd be curious if the new belt helps cure the issue. You do seem to have a little wobble going on.

I am honing in on the alternator bearing or something to do with fan pulley as my culprit. These are tough to diagnose.
 

OwnerCS

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I use a Mechanics Stethoscope to find or rule out engine noises. I recently found a noisy belt idler pulley using a scope like this by touching the probe on the pulley bolt.

1607632750403.png
 
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I use a Mechanics Stethoscope to find or rule out engine noises. I recently found a noisy belt idler pulley using a scope like this by touching the probe on the pulley bolt.

View attachment 2521057
Good call, may be hard to really probe anything on the fan clutch though. I guess it would help eliminate any other pulleys as the culprit.
I turn up the radio.
Nice way to ignore parts that need maintenance. Will have to avoid your rig when it pops up in the classifieds=]
 

Tanner H

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Did you check the four nuts holding the fan/clutch assembly in place to the water pump? put a wrench on each one. It makes that noise when they become loose. Also falls in line with your fan being wobbly.
 
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I took a few more videos and the fan is definitely wobbly. Will replacing the fan clutch do anything or is this the bracket bearing?

thanks!

-john
 
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Did you check the four nuts holding the fan/clutch assembly in place to the water pump? put a wrench on each one. It makes that noise when they become loose. Also falls in line with your fan being wobbly.

Good idea. The four nuts that tighten down to the blue plate that attaches the fan/fan clutch to the fan bracket are tight enough to turn the belt when I try and tighten them down anymore. They were not loose.
 

OwnerCS

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When I recently replaced my fan clutch, the 4 nuts would not stay tight. The serrataion part of the nut had been worn down from being removed during past timing belt jobs. I had to get 4 new nuts to get them to stay tight. From now on, I will replace the nuts anytime I remove the fan clutch.

1607690972442.png


Did you check the four nuts holding the fan/clutch assembly in place to the water pump? put a wrench on each one. It makes that noise when they become loose. Also falls in line with your fan being wobbly.
I took a few more videos and the fan is definitely wobbly. Will replacing the fan clutch do anything or is this the bracket bearing?

thanks!

-john
 
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@jjjewett did you chase down the cause of your chirp ?

no but I have a stethoscope and new fan clutch coming next week. Sure sounds like its coming from the fan.

will do ps flush and new belt this weekend but suspect the fan

If the fan clutch doesnt fix it ill probably just do the timing belt/water pump etc and replace it all at once.

-
 
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no but I have a stethoscope and new fan clutch coming next week. Sure sounds like its coming from the fan.

will do ps flush and new belt this weekend but suspect the fan

If the fan clutch doesnt fix it ill probably just do the timing belt/water pump etc and replace it all at once.

-

Yeah I am in the same boat, everything that spins on the outside with signs of wear have been replaced. Just picked up a new belt for the hell of it to see if that is the culprit. For me the fan clutch appears to be fine with minimal wobble and appropriate resistance, but yours does seem to have a bit of wobble happening.
 
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Fan bracket is a likely culprit. It has a bearing in it. Just do it with every timing belt / water pump service. I had one go bad at about 160k mi. It did not get replaced at the 90k TB/WP services. Live and learn.

Take off the serp belt and spin each item by hand. That will help pinpoint or eliminate items.
 
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flintknapper

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Fan bracket is a likely culprit. It has a bearing in it. Just do it with every timing belt / water pump service. I had one go bad at about 160k mi. It did not get replaced at the 90k TB/WP services. Live and learn.

Take off the serp belt and spin each item by hand. That will help pinpoint or eliminate items.

^^^^^

Good advice right there. You don't want to have to go back and do one later. You're probably 3/4 the way to a full TB job to replace it afterward. Recently did a TB replacement on mine (all components) and found the Fan Bracket was definitely starting to drag, though not making noise yet. Fortunately I already had a new one on hand.
 
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Yep, to get to the fan bracket, I just had my indy do the whole TB/WP service again. You are most of the way in there.. I was bogged down at work with no daylight, so he did it all for me.

I'm about due for the third round soon !
 
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It is almost definitely the fan bracket bearing. I wouldn't drive it as is if you don't have to. If that bearing goes you'll lose your fan, radiator, and maybe more.
Ask me how I know.

Jim
 

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