Alternator or tensioner... how can you tell?

[linuxgod]

I'm at a bit over 101k miles on my 2013 LC. With the COVID lockdown, we haven't driven but maybe once a week to the store for the last 3 weeks. Today my wife gets in and a few minutes after leaving texts me to say she hears a squealing sound. When she got home I opened the hood and leaned over and the sound is definitely coming from the area near the alternator. It's a continuous squealing, not a quiet chirp... when the tensioner or idler went in my Acura MDX is would squeak at startup for about 15-30 seconds, but this is continuous.

For the moment everything seems to be charging right. The voltmeter reads >14V and so does my analog multitester.

First question, what's the best way to determine if the issue is the vane pump, alternator, or belt tensioner? It seems to be charging fine so my hunch is it's the tensioner, but before I start just replacing parts I'd like to actually figure out the problem, especially if a wrong guess means I'm tearing everything down a second time.

Second question, how difficult is replacement? The last serpentine belt I dealt with was on an '86 Olds which wasn't all that difficult but there's definitely less room to work on the LC.

Last question, what are the recommended parts? I'm assuming if I'm getting into this I should do the tensioner, idler, and belt at least. Obviously if the alternator is bad I need to do that... otherwise given the cost I'd not do it until it's bad. At the moment the water pump seems fine, so while it might be a bit more convenient to do it while the belt is off I wasn't planning on draining the cooling system. That said I am at 100k miles...

 

[radman]

As far as detection goes, I usually spray one of the suspects with wd40 or your flavor of choice. If the sound goes away, it's a temporary fix and you know it's the culprit. Otherwise, try the next one until you find it.


Edit: spray with the engine off

 

[bloc]

A mechanic's stethoscope can help you narrow down what is actually going bad. Putting the tip on the front or back of the alternator, or the center bolt in the tensioner (if you can snake it in there without buzzing the fan) will pinpoint any issues really quickly. Personally I wouldn't want lubricant anywhere near my serpentine belt system.

The belt can be done with the fan in place, but most of the other stuff requires pulling it. I've found it easiest to release the tensioner from the bottom with both skid plates removed. Also it's hard to see but there is a pin hole on the tensioner where if you insert the correct size rod (it's in the FSM) it'll hold it back.

For getting the fan out without making a mess I've done this a couple times.
Get a 60mL syringe and some vacuum tubing. With this you can suck coolant out of the top of the radiator to the point that the level is below the bottom of the upper hose connection. Then when you remove the upper hose clamp nothing will spill. Leave the hose attached to the neck on the engine and bend it back.. now you have access to remove the fan and shroud at the same time. Note that there is a plastic cable clamp and two 10mm bolts holding various parts to the shroud. With all of that loose it'll come out.

I did tensioner, idler, and fan bearing bracket recently. Give your bracket a spin. At 150k mine was just starting to make noise. Idler was great, tensioner was getting close to going. Alternator felt perfect. I haven't changed one of those.. it's a big SOB and buried in there, so getting it out could be a chore. I didn't look closely at what would be required for that job while I was in there, sorry.

Coolant shouldn't be left in there forever.. I can't remember if the recommendation was 100 or 120/130. Sure would be convenient to do the pump and thermostat and coolant while you have so much of the front of the engine apart.

Someone on here advocated changing coolant without flushing by the way, and it made a lot of sense. As long as yours is good, a thorough drain and refill will replace the vast majority of what's in the system without diluting the new stuff's corrosion, lubrication, and freezing/boiling point protection.

 

[MHFJ]

Interesting you should mention doing it from the bottom. I have a new belt, idler, and tensioner in the garage for this weekend and I was thinking it may be easier from underneath instead of pulling the fan and shroud.

 

[linuxgod]

Interesting you should mention doing it from the bottom. I have a new belt, idler, and tensioner in the garage for this weekend and I was thinking it may be easier from underneath instead of pulling the fan and shroud.

If you do it, take a few pics and let me know how it goes, how long it takes, and any other cheats or struggles you find. I will likely order the belt, tensioner, and idler this week since no matter what is bad once I get in there and pull the belt off I might as well knock them out.

 

[bloc]

Interesting you should mention doing it from the bottom. I have a new belt, idler, and tensioner in the garage for this weekend and I was thinking it may be easier from underneath instead of pulling the fan and shroud.

I did the job from the top because I had to remove the fan anyway for the bearing bracket. But yes the FSM outlines releasing belt tension from the bottom. There is quite a bit of stuff in the way but it can be done, and is still easier than from the top. Plus the pin needs to be done from the bottom.

 

[04UZJ100]

Spray water on the belt while running or prior to starting. If the sound goes away - you know it’s the belt.

 

[grinchy]

5mm is the pin size. Allen key will work. There's a sequoia alternator change on YouTube, actually doesn't look that bad. They drain the radiator and remove the fan and shroud and water pump too.

 

[Cruisin911]

My money is belt or tensioner. Solid advice above on spraying the items until the sound goes away. With 101k, I'd be in there anyway replacing the belt, water pump, radiator, etc.... On my tundra 5.7 I had 2 of the tensioners go bad and it never squealed. It was always a rattle.

 

[linuxgod]

Definitely squealing like a trapped squirrel...

I ordered a belt, tensioner, and idler pully today. The radiator was done at 75k miles, so I'm good for a while. I've been debating the water pump but I may wait on it - it's not leaking, the failure mode is fairly obvious (and slow) so I will have time to deal with it when the time comes, and while $150 isn't a huge expense at the moment I'm carrying 2 houses so I'm trying to keep a lid on expenses.

 

[MHFJ]

Here's a quick write-up on changing the belt, tensioner, and idler pulley. I probably took too many pictures and went into too much detail, but here it is anyway. I ordered the parts from Dan Deery Toyota online and had them in a couple days for a total of ~$190. I also did most of the work from the bottom, instead of pulling the shroud and fan. Mine had an occasional chirp on startup when it was damp outside. The radiator and water pump had been done by the previous owner, but I don't know the mileage. I'm just at 150k now, and the tensioner sure looked original to me. The new tensioner was much tighter than the old one. I think I spent more time on the stock skid plates than the rest of the job.

Pull the skid plates:

The tensioner has a hole to release tension on the belt. I used a .195 drill bit because it was the first thing I could find.

From underneath, release tension on the bolt with a 14mm socket. If you're laying underneath, it's towards the driver's side. As you release the tension, put the drill bit in the tensioner hole, and the belt stays slack.

 

[MHFJ]

Here's the tensioner with the tension released:

There's a 6mm allen bolt in the center and a 12mm (maybe 14mm?) on the edge of the tensioner. Don't be like me and remove the tensioner with the drill bit still in it. There's a s***load of tension on that thing, and it's a PITA to get out when it's not bolted to something. Take the tension off and remove the drill bit, then remove the belt from the top and bottom and remove the tensioner.

Replace both tensioner bolts and torque to 17 Lb-ft. Go to the top and remove the idler pulley. I believe it was 14mm. Torque new idler to 32 lb-ft.

 

[MHFJ]

Start replacing the belt. I started on the idler pulley side first, then worked around the bottom, then back to the tensioner from the top.

Once everything is lined up, release the tension on the tensioner, and remove the drill bit. Check that all pulleys are aligned correctly, and you're good to go!

 

[CharlieS]

Nice write up, thanks for sharing this! Your skid plates look new - what part of the country/world are you in? My 100k 2013 is a rusted hulk compared to that vehicle.

 

[bloc]

I’d double check those torque values for the tensioner. The bolts are m8 and 32 is roughly double the amount commonly used on that size.

 

[linuxgod]

Thanks @MHFJ, that’s great detail

 

[MHFJ]

Nice write up, thanks for sharing this! Your skid plates look new - what part of the country/world are you in? My 100k 2013 is a rusted hulk compared to that vehicle.

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I’m in Illinois, but my 2013 spent it’s first 148k miles in Atlanta. I was less worried about the mileage and more worried about the rust. It's very weird for an Illinois guy to see a 7 year old Toyota that's rust free.

 

[MHFJ]

I’d double check those torque values for the tensioner. The bolts are m8 and 32 is roughly double the amount commonly used on that size.

You're right. The FSM calls for 32 on the idler, but I never did find specs on the tensioner. I'll edit that.

 

[grinchy]

Excellent and timely. I have the kit for this and might get around to it today. Depends on how quarantine Easter goes.

 

[bloc]

13-16 is often the range for M8x1.25 into aluminum but it’s probably worth trying to find the real number. I’m on a trip or I’d try to find the numbers. I do remember them being really difficult to locate in the FSM, especially if you do the fan bracket also.