Bearing noise from front of engine - how to diagnose?

[OwnerCS]

Just an idea to check.

How old is the fan bracket/bearing? Mine started making a strange whine that would disappear after the engine had warmed up. I never saw the fan pulley bearing wobble or give any classic symptoms.

The strange belt noise I experienced was from the back of the belt making contact with the fan pulley that would not spin as easily as it should. Once I got into checking other bearings, I did find other bearing issues.

When I first checked pulleys with the belt removed, I couldn't determine the fan pulley bearing status with the fan and clutch attached until the problem progressed to the point where it was noticeable the fan pulley bearing was becoming a problem.

The back of the serpentine belt was dragging against this pulley surface.

 

[Mike NXP]

Just an idea to check.

How old is the fan bracket/bearing? Mine started making a strange whine that would disappear after the engine had warmed up. I never saw the fan pulley bearing wobble or give any classic symptoms.

The strange belt noise I experienced was from the back of the belt making contact with the fan pulley that would not spin as easily as it should. Once I got into checking other bearings, I did find other bearing issues.

When I first checked pulleys with the belt removed, I couldn't determine the fan pulley bearing status with the fan and clutch attached until the problem progressed to the point where it was noticeable the fan pulley bearing was becoming a problem.


View attachment 2891500

The back of the serpentine belt was dragging against this pulley surface.

View attachment 2891502

Thanks for thinking about it. So to go back in time I had Toyota do my timing belt job because I am a sissy. Of course, since I didn't specifically tell them to replace idlers and tensioners they only replaced the belt.

Fast forward 10-20k miles and I had a loud squealing, I removed serpentine belt and it was still squealing. So back to Toyota for a full timing belt job which replaced fan bracket, idler, tensioner, etc.

Could they have messed something up? Probably. I even asked for all the old parts and I recall seeing my old fan brackets and idlers which were pretty worn out. Water pump and everything was swapped out at this time as well. That was only 5-10k miles ago


I need to take my belt off this weekend and confirm the noise does actually go away because if I have to go back into the timing belt area I will be pretty disappointed and probably cry for a little while.

 

[2001LC]

I'm hoping to get some help on making sense of this squealing I have coming from my engine.

Over the last year I have replaced every single component that spins, including all timing belt parts. Mostly as preventative maintenance, nothing was broken.

Focusing on the fact that every single pulley and component are new, I am stumped on why my poor engine is squealing.

-It's heard when I first start it up, can be warm out ( 50degF) and it still does it. The noise typically goes away when up to operating temp.
- When 4 wheeling last week , she was working pretty hard mostly in 4 low hill climbing, and I could hear it crying out slightly. It wasn't ready to explode but it was enough to make me worry a bit
- Every part along the accessory and timing belt are new
- Replaced idlers twice because I was convinced they were defective
- On my third OEM belt because I am a moron
- Recently removed belt and cleaned it up to remove any possibly grease. Cleaned pulley
- When I remove serp belt the noise goes away.
- Stethoscope is not helping.
- When I say " I replaced " I mean "toyota service center replaced " but I am capable of diagnosing a bad pulley.

Question

- Are the bearings in the AC within the pulley/clutch or inside the compressor itself? I just replaced pulley / clutch with no difference
- Am I obsessing over something that I shouldn't care about? It's just frustrating to replace so many parts and still have squealing noises.

Good advice, thanks.

All components mentioned are new OEM and check out, that is why I'm so puzzled.

• I can't seem to get the AC to click on recently when temps are this cold, even when set to max cold.
• Power steering pump is not that old, replaced with OEM, and flushed fluid at the time with Toyota ATF.
• Steering rack was also just replaced, flushed fluid at that time as well
• Turning the wheel doesn't change the noise
• With the serpentine belt off, the noise goes away which is a relief

This morning with the stethoscope out I was able to touch the AC compressor and the idler pulley and could hear the noise with the engine running. That idler pulley has been replaced twice in the past year or so with a new pulley / bearing from Toyota. First time because it was free spinning, second time because I thought it was the culprit of another noise ( which was timing belt related )


I've got to get the belt off this weekend and dive into it a little deeper because the noise seems to be heard through several components when the belt is spinning.


PS - Reading back through this thread I really hope people aren't shoving socket extensions into the engine bay and trying to listen to noises. Stethoscope is less than 10 bucks.

Thanks for thinking about it. So to go back in time I had Toyota do my timing belt job because I am a sissy. Of course, since I didn't specifically tell them to replace idlers and tensioners they only replaced the belt.

Fast forward 10-20k miles and I had a loud squealing, I removed serpentine belt and it was still squealing. So back to Toyota for a full timing belt job which replaced fan bracket, idler, tensioner, etc.

Could they have messed something up? Probably. I even asked for all the old parts and I recall seeing my old fan brackets and idlers which were pretty worn out. Water pump and everything was swapped out at this time as well. That was only 5-10k miles ago


I need to take my belt off this weekend and confirm the noise does actually go away because if I have to go back into the timing belt area I will be pretty disappointed and probably cry for a little while.

I'm a bit confused. Twice you state noise gone with belt off. Than you say : "I need to take my belt off this weekend and confirm the noise does actually go away"

AC not working is biggest clue you've given!
Also make sure drive belt tension has a good amount of tension (pull back). I've seen some that just don't have good spring tension, so belt slips.
Also fan brackets, even new OEM, do fail. Stick your stethoscope on fan bracket housing.
Idler pulley seated in backward and run, can damage bearing. I saw one guy claim a certain brand idler junk, 3 replacement failing within 5K miles. He installed backwards. Also note the washer cap plate of pulleys, must not rub. Sometime they get switch with tensioner cap washer. Then some will not fit well.

 

[Mike NXP]

I'm a bit confused. Twice you state noise gone with belt off. Than you say : "I need to take my belt off this weekend and confirm the noise does actually go away"

AC not working is biggest clue you've given!
Also make sure drive belt tension has a good amount of tension (pull back). I've seen some that just don't have good spring tension, so belt slips.
Also fan brackets, even new OEM, do fail. Stick your stethoscope on fan bracket housing.
Idler pulley seated in backward and run, can damage bearing. I saw one guy claim a certain brand idler junk, 3 replacement failing within 5K miles. He installed backwards. Also note the washer cap plate of pulleys, must not rub. Sometime they get switch with tensioner cap washer. Then some will not fit well.

You're right. Last winter I had the same noise and I was pretty confident I took the belt off and the noise went away so I stopped caring for a while. Fast forward to this year and I am doubting that I ever did that so either way I need to start fresh and double check with the belt off.

The AC clutch/pulley was replaced last summer by Toyota and they removed the compressor to do so. They recharged the system then and it was blowing ice cold. Lately it's been single digit temps in the morning and I don't hear it engaging even on max cold.

Good advice on the other possible suspects I will double check and make sure everything is installed properly. The stethoscope made it a bit hard though because I can hear the noise on a few different areas. I need to remove the belt and start spinning by hand to try and make sense of it.

With no clear failing parts I'm destined to just wait for it to get worse because I can't keep throwing parts at this rig. History below. Seems like the toyota owners portal is no longer showing the dealer repairs, only self reported.
>>

 

[2001LC]

AC should run. It actually is also part of defrost. In that it drys the air so window don't fog up in cold weather. I turn my off, but that's me.

Having work done at Dealership (Toyota or Lexus) is usually good work. But I do get a lot from dealership shops, very messed up.

 

[Mike NXP]

AC should run. It actually is also part of defrost. In that it drys the air so window don't fog up in cold weather. I turn my off, but that's me.

Having work done at Dealership (Toyota or Lexus) is usually good work. But I do get a lot from dealership shops, very messed up.

Yeah, they have been pretty decent so far when I am specific on the work I want done. I double check a lot of their work but there only so much I can do on my own. I'll dive into it a bit this weekend otherwise I am stumped and need to move on.

Is there any sort of air gap or something along those lines with the AC clutch that Toyota could have screwed up that I need to consider? I would think any problem relating to improper install or anything of that sort would not go away once warm.

The symptoms and noise just point to a idler or tensioner failing but they all check out.

Thanks for the help all, I'll keep digging into things and report back if I find anything note worthy.

 

[2001LC]

I really don't know on the AC. But I would "think" sound would go away or change once clutch engaged, if it does engage. Check. Also try spinning once belt off.

 

[2001LC]

BTW. I just had a report on a sound that was intermittent we could not find. Started after Lexus worked on this LX570.

Report was: PCV valve replaced, solved!

 

[Mike NXP]

BTW. I just had a report on a sound that was intermittent we could not find. Started after Lexus worked on this LX570.

Report was: PCV valve replaced, solved!

Nice find! Mine was replaced with OEM within the past year or so , I'm chasing a different suspect =[

 

[Mike NXP]

So the stethoscope helped a bunch this morning. I can clearly hear the chirping coming from the idler pulley when I put the prob right on the bolt.

I replaced this idler with oem not that long ago so I'm not sure how it failed so quickly . Could it really be that simple , I'm going to swap the bearing and see if the diagnosis was correct.

@2001LC I did so digging but saw a few part numbers floating around , can you tell me what the go to aftermarket bearing replacement is for the idler pulley or should I replace the entire pulley with oem again ?

 

[2001LC]

So the stethoscope helped a bunch this morning. I can clearly hear the chirping coming from the idler pulley when I put the prob right on the bolt.

I replaced this idler with oem not that long ago so I'm not sure how it failed so quickly . Could it really be that simple , I'm going to swap the bearing and see if the diagnosis was correct.

@2001LC I did so digging but saw a few part numbers floating around , can you tell me what the go to aftermarket bearing replacement is for the idler pulley or should I replace the entire pulley with oem again ?

OEM pulley is best long term option. We really don't have a good bearing, we can press into idler pulley.

If your last replacement was OEM. Very rarely do they go bad in less than 90K miles, even then only a chirp. Unless installed backward or wrong retain plate or not seated.

 

[Mike NXP]

OEM pulley is best long term option. We really don't have a good bearing, we can press into idler pulley.

If your last replacement was OEM. Very rarely do they go bad in less than 90K miles, even then only a chirp. Unless installed backward or wrong retain plate or not seated.

Good call, Toyota said they will warranty this part since I got it April of last year, so that's good to know.

I pretty much overlooked this part because it was replaced recently and like you said rarely go bad that fast. With the stethoscope on the idler bolt I could clearly hear the chirp chrip chirping. In the past I was kind of probing at the retaining plate and it wasn't as clear to hear as when I probed the bolt. I possibly installed something wrong but I'll take a closer look once I pull it off.

Hopefully it's as simple as that, will report back soon.

 

[2001LC]

Once I hear the chirp. I do like to pull serp belt and confirm. By spinning pulley(s) by hand. Which I show a video of in post #38.

 

[Mike NXP]

Once I hear the chirp. I do like to pull serp belt and confirm. By spinning pulley(s) by hand. Which I show a video of in post #38.

I will do just that before removing it and will make sure the retaining plate and everything is installed right. Luckily Toyota will warranty it either way so I may be destined to just swap it out anyway.

 

[Mike NXP]

I will do just that before removing it and will make sure the retaining plate and everything is installed right. Luckily Toyota will warranty it either way so I may be destined to just swap it out anyway.

Alright belts off. I'm going to run the engine once it's cold in the morning to make sure timing belt components are not part of the suspect list.

All the pulleys fell smooth and the tensioner is strong . Nothing free spins or binds up. I pulled off the idler and was hoping I'd feel some sign of failure. It has a lot of dust / dirt built up on the backside.

I put it in the freezer a while and then spun it by hand . It barely spins one turn but feels smooth. I think that's pretty normal?

I wish I had away to spin it faster with a drill or something to see if it chirps.


The fact remains that with the stethoscope touching the bolt of this idler the noise was very clearly coming from there, it was actually kind of cool to hear it so clearly.

 

[OwnerCS]

Alright belts off. I'm going to run the engine once it's cold in the morning to make sure timing belt components are not part of the suspect list.

All the pulleys fell smooth and the tensioner is strong . Nothing free spins or binds up. I pulled off the idler and was hoping I'd feel some sign of failure. It has a lot of dust / dirt built up on the backside.

I put it in the freezer a while and then spun it by hand . It barely spins one turn but feels smooth. I think that's pretty normal?

I wish I had away to spin it faster with a drill or something to see if it chirps.


The fact remains that with the stethoscope touching the bolt of this idler the noise was very clearly coming from there, it was actually kind of cool to hear it so clearly.

Is this the small idler pulley at the top? I just had to replace an OEM one that was roughly 9 months old. There is a cavity on the backside of that pulley where mud likes to collect. I attribute the short life to my off-roading use case with a lot of mud and water crossings.

 

[Mike NXP]

Is this the small idler pulley at the top? I just had to replace an OEM one that was roughly 9 months old. There is a cavity on the backside of that pulley where mud likes to collect. I attribute the short life to my off-roading use case with a lot of mud and water crossings.

Yeah exactly , I may be up against the same issue. What signs of failure did you have , chirping / squealing on cold morning ? The bsckside of the pulley has a lot of dust buildup around the bearing and in the pulley . I would think the sealed bearing would resist the debris but maybe just a little bit gets in there .

When Inspecting it by hand it feels fine and spins pretty smooth but the stereoscope tells a different story. I'm going to replace it tonight with oem pulley and see if the noise is gone .

 

[OwnerCS]

Yeah exactly , I may be up against the same issue. What signs of failure did you have , chirping / squealing on cold morning ? The bsckside of the pulley has a lot of dust buildup around the bearing and in the pulley . I would think the sealed bearing would resist the debris but maybe just a little bit gets in there .

When Inspecting it by hand it feels fine and spins pretty smooth but the stereoscope tells a different story. I'm going to replace it tonight with oem pulley and see if the noise is gone .

Almost the same situation. When I was probing for noises, placing the stethoscope on the pulley bolt revealed noise. When I removed it and spun it by hand, I could tell it wasn't like new. I still have that OEM pulley. It should be under warranty and I may return it. I did purchase a Gates pulley from O'Reilly that does not have the cavity to collect mud. It's too early to tell how long that pulley will last for me to recommend it. Also, I use the 100 in a heavy off-roading scenario with a lot of mud and water crossings.

Based on my off-road requirements, I'm not surprised that I may need to look for alternatives or accept more frequent replacements than a user that stays on the pavement or maintained roads. It seems to go with the territory.

 

[Mike NXP]

Almost the same situation. When I was probing for noises, placing the stethoscope on the pulley bolt revealed noise. When I removed it and spun it by hand, I could tell it wasn't like new. I still have that OEM pulley. It should be under warranty and I may return it. I did purchase a Gates pulley from O'Reilly that does not have the cavity to collect mud. It's too early to tell how long that pulley will last for me to recommend it. Also, I use the 100 in a heavy off-roading scenario with a lot of mud and water crossings.

Based on my off-road requirements, I'm not surprised that I may need to look for alternatives or accept more frequent replacements than a user that stays on the pavement or maintained roads. It seems to go with the territory.

Good info thanks. I don't find myself in mud often but the dust around here in the summer is out of control . Toyota was willing to replace mine under warranty no questions asked. Worth a try for yours as well.

 

[OwnerCS]

Good info thanks. I don't find myself in mud often but the dust around here in the summer is out of control . Toyota was willing to replace mine under warranty no questions asked. Worth a try for yours as well.

I'll get it replaced to at least have a spare. The most recent OEM is in the center with mud in the cavity. The OEM on the right was replaced with the one in the center.

Again, too early to tell how long the one on the left will last.