Bizarre Front End Engine Sound - Squirrelly Serpentine Belt, Harmonic balancer wobble

So I replaced my serpentine belt, fan clutch bracket (but not fan clutch), idler pulley, and belt tensioner less than a month ago. Has been running great until a few days ago. It sat for a week over thanksgiving and when I came back I discovered that coolant had been leaking out of my thermostat housing right onto the belt. And since then there’s been a weird intermittent chirping noise from the engine, and sometimes, usually when I’m accelerating, there is a really weird and concerning scraping sort of noise that sounds a lot like the serp belt is misaligned or about to fall off.

- At idle there is no sound from it.
- I can visibly see the belt oscillating about 1 millimeter side to side on the belt tensioner.
- Belt also has a wobble coming in to and away from the tensioner.
- at least at idle, the belt is aligned as it should be in all the grooves in all the pulleys.
- the harmonic balancer/ crank pulley has some visible wobble to it. I’m thinking that’s not normal, but it also had it prior to this.
- fan and fan clutch have some wobble to them as well, but the belt has no wobble at all when it is on that pulley.

I’m gonna take off the belt, make sure all the other pulleys are good etc but I honestly don’t think they are the problem. I’m thinking it’s either the harmonic balancer or maybe that slight coolant leak causes the belt to slip, or maybe it’s the new gates pulley tensioner. That’s all I can think of. Perhaps I installed something wrong and that’s leading to belt misalignment but it all looks good and I’d expel it to have appeared right off the bat.
My search resulted in like 1 thread ever mentioning the harmonic balancer/ crank pulley having issues on our trucks so that makes me wonder.
I’ll keep working on it and updating, any advice would be greatly appreciated.

 

Off the top of my head: I would not, ever, be too concerned with an OEM crank pulley; they are very stout, even aged ones. Doesn't mean they never fail or can't fail, but very rare. I would concentrate on components above the crank pulley. The scraping sound is concerning because it isn't normal. My focus would be there on related components since it has been a recent discovery. Toyota/Aisin components or risk is assumed.

 

I would start here. When was the TB replaced? Did you do it? It's possible that the bolt on the crankshaft pulley wasn't torqued to the correct spec (181 ft. lb.) and it's working it's way loose. Bad deal. Make sure everything else it torqued to spec when you take the serpentine belt off. Check the bearings in the idler pulley and tensioner pulley to make sure they're good.

 

Does it happen to be cold when this happens? Check your parts sourcing...there's a TSB for this.

 

Welp, the brand new gates belt tensioner appears to to have some definite wobble to its spin. So that is at the very least the reason for my belt oscillation, still confused as to why it happened when it did but I will replace it and we shall see. At least the fan bracket is Aisin.

Timing belt was claimed to have been replaced around 2 years before I bought it in August, no paperwork for it, but the belt does look new. I doubt it was a proper aisin belt. I'll check that crank pulley torque tomorrow and report back. Is there anything special when I am torquing it? Just don't wanna mess with internals.
- Idler pulley is new and spins well. So does the tensioner, but its just out of round. I made sure they both spun easily and smoothly before I put them on, I must not have noticed that the tensioner was out of round. But it does make me wonder if the crank pulley's wobble made it develop a wobble too, but that seems highly doubtful.

I'll post a video of the crank pulley spinning and see what you guys think.

 

Oh yeah, I just saw that, this is more of a random chirp and sometimes scrape noise that happens when driving, and I always let it warm up. But that is a thought.

 

Holding it so it doesn't rotate is the hardest part. Generally a chain wrench with some rubber wrapped around the pulley to prevent damage is the recommended way. Bring a buddy and a breaker bar for the most painless results. I was able to do mine by myself, but it took some doing. I also had the radiator out which gave me some room to work. I would put a piece of cardboard up against the radiator to prevent bending fins or other damage.

 

Update: Put in a new belt tensioner (still gates because I am going warranty), it spins nice and circular, but DOES NOT solve my problem. There is still the chirping and then dry scraping sound.

Did some diagnosing while it was in park and it appears that the sound (at least the scrape) is probably coming from the fan clutch itself. It has more than a half an inch of play side to side when we wiggle it, and when my dad was revving it, at right around 2k rpm the scraping starts and the fan clutch looks like it is having a hard time clutching.

It might not be my only problem, the belt does still wiggle side to side, but I am definitely going to get a new fan clutch. Any recommendations would be great!

Thanks! I do have access to a 20+" torque wrench so that will be nice.

Is it bad if the crank pulley gets spun at all when torquing? I thought I remember someone saying it isn't great for the engine if it gets spun.

 

The clutch isn't the problem. The fan mounting bracket is. It has a bearing on the mount itself. Replace the whole mount, this is very common issue. Do you need the part number?

 

I have a brand new Aisin bracket on there, I guess that the new one could be bad, but it was Aisin purchased from rockauto part number

$117 AISIN FBT002 AISIN FBT-002 Fan Pulley Bracket - Compatible with Select Lexus GX470, LS400, LX470 Toyota 4Runner, Land Cruiser, Sequoia, Tundra

AISIN FBT002.
I'll upload a video here in a second, it isn't visually helpful but the audio is good.

Do I have to post it to youtube then link it?

 

Ah, yes I just realized I told you about that bracket in a previous thread. Ooops.

All you need to do to embed a video is paste the link to YouTube.

 

Here's another example of bad bracket, note 2nd video:

https://www.tundras.com/threads/help-diagnosing-rubbing-sound-coming-from-engine-1st-gen.145883/

I wish I could find the thread recently where you can see someone actually wobbling the bearing on the bracket. But maybe you can identify with the vids in that thread.

 

https://youtube.com/shorts/FL5K-MaB8Oo?feature=share

My truck definitely idles like a diesel similar to the truck in your linked video.

Let me know what you think. The sound seems real weird to me. The truck almost felt like it was stalling when I started decelerating , but it didn't, and I doubt it was.

 

I recommend giving this a shot.

 

Ah, makes sense. I'll give that a shot.

Is it normal to be able to wiggle the fan clutch more than half an inch?

 

When you say "wiggle the fan clutch, where are you wiggling from, are you grabbing the fan blade and moving it up/down, pushing it in/out, or other?

When you spin the fan, like grab it and forcibly throw it, how many rotations does it complete?

 

Wiggle as in grab fab blade and push it in/out.

When I attempt to spin it by hand it can move maybe 3-4 inches before it stops, and feels like it has a little bit of resistance the whole time.

I will do that test with the serp belt off tomorrow, but I did just have it off, and I know that the idler pulley and tensioner definitely are good, as well as the fan bracket. The rest I haven't attempted to test properly by hand, but I've spun them a little bit to clean them and nothing seemed off but don't quote me on that.

 

And when pulling in/out, is the movement happening at (A) the pedastal part or (B) the finned part, or neither?

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Movement happens at (A) , appears to be at the top of the shaft (A) where it meets (B)

 

I mean, the only thing that makes sense to me in that case is the fan clutch itself is bad.

For the V8 trucks, this is the OEM Aisin part for 2000-2002, and then this one for the 2003-2004, and lastly this one for the 2005-2006.

Under $90 for the '03-04 and '05-06. Not sure why the '00-02 is +60% more.

 

Yes, just based on OP's descriptions in this thread, the thermostatic clutch assembly needs replaced.

 

Thanks guys!

Anybody know if it’s possible to run an 03-04’ on an 00’?? It looks very similar. I don’t fancy paying $140.

There’s a part of me very interested in running electric fans with an aluminum radiator , mostly just to free up serpentine belt because I wanna supercharge it. Idk if I ever will be able to tho. My radiators age is unknown and has had green coolant in it for an unknown amount of time so I would take this as the opportunity to do the recommended proactive replacement , but Having read other threads on it, it really doesn’t seem like electric fans/ aluminum radiator are worth it except for special cases. Thoughts? $140 for the 00’ fan clutch plus $140 for Denso radiator makes the $280 champion radiator plus $70 fan look quite appetizing

 

Aisin is pretty clear with their compatibility and if you look at the pictures, it looks like the physical size of the part is different, potentially bolt pattern different?

I looked up the part with Toyota and it appears OEM direct from Toyota is roughly the same (~$150). Part number is 16210-50080. Heinous. If you need budget, maybe hit a nearby junkyard and find another '00-'02 with a V8 that's still intact? I'd feel silly replacing dead with used, but it's a viable stop-gap when needed, I've done it before in the past plenty of times.

I just don't see another brand of part in their list I'd personally trust and I sure as hell won't trust anything the local parts store offers up...

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My thoughts are the average driver would do well to stick with the manufacturers set-up and specs. Purchase the correct thermostatic fan clutch for your MY and the Denso radiator.

 

Keep us posted on what you discover, please

 

My plan is to go with a junkyard one, only $35 plus probably the same amount in gas. I’ll update when I install! Will probably be a few weeks, going on a trip.

 

For just a little more than that you could have a new one. Hmu in a PM and I'll help you out.

 

Update: Got a new Aisin fan clutch on there and a few hundred miles later the crazy sound in the video is gone. So thats good.

Truck still has a knock of sorts, idles louder than some diesels, and blows smoke at start up.

 

Puff of smoke at startup can be a symptom of a bad power steering air control valve. Look for a black part that about as big as a stack of 7-8 quarters and two vacuum hoses coming out of it, attached above the power steering pump . Pop off the hoses and see if either one has power steering fluid coming out of it. If they do, the valve has failed and you’re sucking power steering oil (ATF) into your intake and it’s getting burnt at startup.

Regarsing the knocking … do you have any codes set? That’s the whole point/purpose of the knock sensors, to detect knock. If you’re hearing knocking sounds but the knock sensors aren’t kicking up codes, that’s be weird.