Clicking noise near serpentine belt

[secondcor521]

1993 Lexus GS300 with about 197K on the odometer.

I'm hearing a moderately loud clicking noise which is coming from the front of the engine in the area of the serpentine belt / radiator fan.

It goes away when (a) the engine is off (duh) and/or (b) the A/C is turned off.

The mechanic suspects it is the drive belt tensioner.  I think it may be the serpentine belt itself.

AFAIK, neither the tensioner nor the serpentine belt have ever been replaced - they are both original to the car.

I did spray some (ok, a lot of) belt dressing on the serpentine belt earlier and plan to see if that makes the problem go away temporarily.  If it does, I think that means it's more likely to be the belt.

The sound is definitely not from the main engine block.

I have an appointment on the 31st for the mechanic's shop to further diagnose and fix, but the way he talked about this particular repair made me think he was going to do a guess-and-check style approach, which I am not keen on even if I can afford the repair goose chase.  (I think my mechanic thinks that my car is old enough that I should just chuck it and buy a newer car.  He and I will probably not see eye-to-eye on this, unfortunately.  Other that that, I think he's a good mechanic.)

Thoughts?  Opinions?  Ways to diagnose?

[ChickenStash]

I'd be surprised if a clicking noise would be the belt, itself. That said, I would replace it proactively as 197k is well past the usual maintenance interval. The tensioner is a likely culprit, particularly if the AC is on. The AC compressor creates a vibration of sorts on the belt system as it runs that could manifest as a click in a loose tensioner as it tries to keep an even tension on the belt.

A quick and dirty check is to remove the belt and feel for any play in the tensioner pulley or spring/mount. Spin the pulley and feel/listen for any scraping or roughness. Do the same for all the other belt-driven accessories you can get your hands on. Everything should spin smoothly and be solid with no play. (Generic advice. I haven't worked on that particular car.)

ETA: This is assuming the clicking isn't just the A/C compressor turning on and off. How often to hear the click? Couple of times per second? Once every few seconds?

[sonofsven]

My first thought was water pump but you say it's not from the block area.

[secondcor521]

I'd be surprised if a clicking noise would be the belt, itself. That said, I would replace it proactively as 197k is well past the usual maintenance interval. The tensioner is a likely culprit, particularly if the AC is on. The AC compressor creates a vibration of sorts on the belt system as it runs that could manifest as a click in a loose tensioner as it tries to keep an even tension on the belt.

A quick and dirty check is to remove the belt and feel for any play in the tensioner pulley or spring/mount. Spin the pulley and feel/listen for any scraping or roughness. Do the same for all the other belt-driven accessories you can get your hands on. Everything should spin smoothly and be solid with no play. (Generic advice. I haven't worked on that particular car.)

ETA: This is assuming the clicking isn't just the A/C compressor turning on and off. How often to hear the click? Couple of times per second? Once every few seconds?

Your second paragraph makes me want to just take it to the mechanic and pay him money.  I've removed the serpentine belt myself once (to replace the alternator) and I know about the tensioner and I can see how it works.  I know the belt drives other stuff, including the radiator fan and probably an A/C compressor.  But beyond that I don't know details.

The clicking is nearly continuous - so several times per second I would estimate.

@sonofsven, I don't think it's the water pump, although AFAIK the water pump is also original, so I suppose it could be.  I've heard that mentioned as a possibility (in addition to valves, alternators, and others).

[ChpBstrd]

I would think the AC compressor is a more likely culprit than the belt. Maybe see if something is loose on the pulley or mounting? Or maybe the compressor is going out?

[sonofsven]

If only we still had Click and Clack, the Tappet Brothers, to ask!(showing my age)

[secondcor521]

I would think the AC compressor is a more likely culprit than the belt. Maybe see if something is loose on the pulley or mounting? Or maybe the compressor is going out?

Possibly.  I've watched the belt with the engine running, and it looks OK to me, but I might not know what "not OK" looks like.  The belt doesn't look frayed, or damaged, or loose.

[svosavvy]

When the tensioner is on its way out it usually makes the belt look a little "jumpy" as well.  I would have someone watch the belt while another helper turns the car on/off and turn the a/c on/off.  The belt should look smooth as silk the whole time.  Tensioners are pretty cheap you could replace that and hope it fixes the problem.  If it doesn't, like you said probably the bearings in your a/c compressor are on their way out.  Watch the actual tensioner and see if there is any hop movement.  Eventually your click will progress to a grind/squeel.  You could remove the belt and check all your bearings (a/c, alternator, smog controls, tensioners, etc) for play and/or detectable non smoothness.  When bearings are on their way out you will get a lot of heat where they are housed.  Obviously when the car its off and doing so carefully you can check for excessive heat buildup in your bearings.  Hope that helps.

[svosavvy]

you can also try to spray a little lube into the suspected bearing.  This will usually make the bearing behave well for about 5 minutes.  If it magically cures the problem you know your bearing is shot and then replace.

[secondcor521]

Thanks all.

I ended up spraying a lot of belt dressing on the belt, which seemed to make the problem go away for a day or two.

I also tried taking the belt tensioner tension off with a socket wrench, and it was more difficult than I remembered (when I replaced the alternator), so it seemed like maybe / probably the tensioner was frozen.

I took it in to the mechanic and he - after lecturing me to never ever use belt dressing again - cleaned off the belt dressing, replaced the tensioner, and replaced the belt.  Problem solved.

Good for the next little while, anyway!

[Artem_F]

OK, I'm kind of late to the party, but there's an inexpensive device, which can help to find the source of annoying sound. I'm speaking of mechanics' stethoscope, which can be found for a few $$ at Harbor Freight or elsewhere. Of course, you can't test the rotating parts, but you will definitely be able to isolate the sounds coming from A/C or from a pump, or from an alternator. I guess, you may even be able to test the tensioner because its arm is (should be) partially visible.

[sonofsven]

Thanks all.

I ended up spraying a lot of belt dressing on the belt, which seemed to make the problem go away for a day or two.

I also tried taking the belt tensioner tension off with a socket wrench, and it was more difficult than I remembered (when I replaced the alternator), so it seemed like maybe / probably the tensioner was frozen.

I took it in to the mechanic and he - after lecturing me to never ever use belt dressing again - cleaned off the belt dressing, replaced the tensioner, and replaced the belt.  Problem solved.

Good for the next little while, anyway!

Well good job, you figured it out.
What's the problem with belt dressing, according to your mechanic?
I just sprayed some on my old 70's van.

[sisto]

OK, I'm kind of late to the party, but there's an inexpensive device, which can help to find the source of annoying sound. I'm speaking of mechanics' stethoscope, which can be found for a few $$ at Harbor Freight or elsewhere. Of course, you can't test the rotating parts, but you will definitely be able to isolate the sounds coming from A/C or from a pump, or from an alternator. I guess, you may even be able to test the tensioner because its arm is (should be) partially visible.

This is exactly what I was going to suggest. You can also make one, though not as good, with a long screwdriver.

[secondcor521]

Thanks all.

I ended up spraying a lot of belt dressing on the belt, which seemed to make the problem go away for a day or two.

I also tried taking the belt tensioner tension off with a socket wrench, and it was more difficult than I remembered (when I replaced the alternator), so it seemed like maybe / probably the tensioner was frozen.

I took it in to the mechanic and he - after lecturing me to never ever use belt dressing again - cleaned off the belt dressing, replaced the tensioner, and replaced the belt.  Problem solved.

Good for the next little while, anyway!

Well good job, you figured it out.
What's the problem with belt dressing, according to your mechanic?
I just sprayed some on my old 70's van.

He says that it creates a messy gunky work environment when repairs have to be done (such as replacing the belt tensioner).  I can see that - it can get all over the pulleys and the rest of that area of the engine, and if dust or dirt or any other type of particle is there they could mix / stick together.

He also says it doesn't actually fix anything or do anything good.  I think his point of view is if there is squealing or chirping or clicking in the belt area, it's better to just root cause and fix it rather than covering it up / making the noise go away.

[ChickenStash]

I like that answer from the mechanic. Sounds like a keeper.

[secondcor521]

I like that answer from the mechanic. Sounds like a keeper.

He's great except he doesn't like working on old cars.  Says it's hard to find parts and hard to have techs trained on them, which is reasonable.  He owns and runs the shop and I get the impression that he is the one who works on my car because the techs he has only know newer stuff.  At some point he's going to get tired of working on my car.  I hope not for several more years though, as I like the car and it's been generally reliable so far.

[Dave1442397]

I like that answer from the mechanic. Sounds like a keeper.

He's great except he doesn't like working on old cars.  Says it's hard to find parts and hard to have techs trained on them, which is reasonable.  He owns and runs the shop and I get the impression that he is the one who works on my car because the techs he has only know newer stuff.  At some point he's going to get tired of working on my car.  I hope not for several more years though, as I like the car and it's been generally reliable so far.

My mechanic said he stopped working on old cars completely because of the delays in getting parts (pre-COVID). He had three lifts in his shop, and he said sometimes there's be an old '60s or '70s car stuck up there for days at a time because it was dismantled and waiting on parts. That prevents him working on other cars, which costs him money.