danmm7

Hi guys!

My 2005 GX470 with 130k miles on the clock, last weekend developed an high-pitch whining noise that is engine RPM dependent. It changes as the rpm go up or down. You can hear it at idle but it becomes more noticeable around 1600-1800 rpm, and then the engine noise covers it.
I was 300 miles away from home when it started to happen but luckily, we drove back with no issues. The noise did not get any better or worse. It is still there. No warning lights. No vibrations. No leaks. Car runs just fine.

I went under the car this morning with a mechanics stethoscope and as soon as i touched the alternator it became obvious that the noise is coming from there. It is very loud when using the stethoscope. The AC, the PS pump, and the idler pulley are very quiet. The belt tensioner also emits some noise but i blame it on its close proximity to the alternator. I hope i am not wrong on this.

Here are a few questions...

1. Does 130k miles (12 yrs) sound right for this car to need a new alternator?
2. This sounds to be a bad bearing issue. The voltage coming from the alternator was 13.8 V this morning. Seems very healthy to me. There is a local place here that is very well rated for REBUILDING alternators and starters. Given that i am dealing with a bearing issue, would you recommend i take it to them or should i just buy a NEW alternator?
3. Assuming that i decide to buy a new alternator, should i go with Denso unit... or is there a better, more robust and reliable option for our cars?
4. For those who have replaced it in the past, are there any tricks / tips to this repair? I am a DIY guy and i have replaced alternators on other cars, but never on a GX470.

Thanks!
Dan

chiph9

See if this thread helps.

https://www.clublexus.com/forums/gx-...e-w-video.html

Chip H.

snhrph

I had to replace mine last month. I used to be a mechanic and still work on cars regularly. I decided to take it to the shop and let them do it. Replacing an alternator on GX can be a DIY
project, although a difficult one. It's a lot easier if you have a lift.

But anything is possible.

Booyah

mine went out at about 70K 2008

RPH74

I just did this job a couple of weeks ago. This YouTube video is what I used as my guide.


The biggest snag that I ran into is that the top right nut did not come off easily. It actually took the screw/post that the alternator hangs on with it. I needed a 14mm thin wrench to hold the post down and break the nut loose, and apparently nobody in my town stocks this tool. So since it was a Saturday night, and I didn't want to wait until midweek to have a thin wrench I ended up grinding a normal 14mm wrench down to fit. What a *****.

Otherwise it's a fairly straight forward job. Though I do remember cursing Toyota's name a few times for locating the alternator in such an awful place, instead of right on top as many vehicles do.

Just shout out out if you need help!

RPH74

Here's a pic of the nut that wouldn't let go of the post. Much easier than trying to describe it. Just in case this happens to anyone else, you need a thin 14mm wrench to hold the post to loosen the nut.

danmm7

I got the alternator out yesterday. It was not too bad. Took me about 1.5hrs, from start to end. The biggest challenge was removing the PS pump pulley since i had hard time locking it in order to remove the nut.
Took the alternator to a local reputable rebuilt place. We put it on stand and it immediately became clear that it makes a bad noise. The noise was blamed on bad rectifier. Not sure if this makes too much sense.
They will fully rebuild the OEM unit and i should have it ready tonight.

Let hope the install is as easy or easier.

RPH74

Well done sir!

What did you end end up using to hold the alternator pulley? I used a socket extension just like the video did.

Dont forget to use locktite or other thread locker paste on that Power Steering pulley bolt when reinstalling.

danmm7

All done! New (rebuilt) alternator went right in. I did not even remove the sway bar bolts. At the right angle, the alternator can get in and out between the frame and the sway bar.
I did put thread lock on the PS pulley nut, just in case.
I used the handle of a thick ratchet to hold the PS pulley in place. It worked really well. I installed a new belt as well, since the original one had more than 30k miles on it.

Car runs quiet again!! Smooth and no noises at any rpm.
This was not a hard project, nor it was costly. My original Denso alternator was rebuilt for less than $130. It looks like new. I spent 2.5-3hrs total working on the car, not using a lift or any professional shop tools.

Thank you all for the tips and help. The YouTube video shared above is VERY helpful. Too bad i saw it after i already removed my alternator.
The only thing i did different from the video was to NOT remove the sway bar.

RPH74

That's impressive work. It's always satisfying to be able to tackle these things on your own!

RushNatU

I also ran into the same issue with that bolt not wanting to let go. I ended up stripping it due to such soft material and the nut being undersized for my Craftsman 10mm wrench. After struggling in the tight space for an hour, I took my dremel amd cut the alternator casting around the stud, then took a prybar between the block and alternator and it popped right off. After the old alternator was out it was easy to get vice grips on the remaining bolt to get it off the stud. If all goes smooth, this can be done in an hour and a half or less instead of two and a half.

deeken

Looks like my alternator is shot and now I gotta replace it. I removed the lower skid plate and took a look from underneath and I can't see how this is anywhere near a 1.5-2 hour project. There is just crap everywhere and it's all in the way. I don't know how these SOB's (Toyota) could have the put the damn thing in such a difficult place. I'm not sure if I want to do this on my own or just have a mechanic take care of this. Just from what I can see and all the rusted bolts, removal of the power steering pulley, hoses, etc I'm thinking a 3-4 hour job at least with regular tools.

What is a reasonable rate to pay someone to get this done? On top of this nonsense I noticed that the my passenger side CV boot has a tear and grease is leaking all over the place.

RPH74

Once you lower that sway bar, it really opens things up and makes the job easier. Since you live in the NE, rusty bolts could make some of this more difficult than it was for me. I'd say 4 hours is a good estimate for a DIY job assuming no snags like I had with the bolt sticking to the post.

I would think a shop would only charge 2, maybe 3 hours of labor to do it.

And yes, I don't get why Toyota placed the alternator down low like that. My Chevy and Dodge trucks had the alternator up top, for easy replacement and further away from water. Toyota usually does things right but this is one I don't like.

kmchuk

I am trying to diagnose if my alternator is going bad causing my battery to fail. My GX was taking longer to start so I trickle charged the battery and it started fine for couple of days but that only lasted for couple of days. The 4year old battery was showing 10.6v so I assumed a cell failure due to TX heat and bought a new Toyota Truestart 27F battery from dealer. I bought this vehicle couple of weeks back, it has re-manufactured toyota alternator, so it was replaced before.

Voltage at idle, 700RPM, all accessories off : 13.66v
Voltage at 2500RPM, all accessories off : 13.78v
Voltage at 700RPM, AC on, Radio On, HeadLights On : 13.5v
Voltage at 2500RPM, AC on, Radio On, HeadLights On : 13.6v

Do the above numbers look normal? or do they showing signs of alternator failure?. My other car BMW 330 shows 14.2v at idle, lot of youtube videos also show 14.2v idle voltage.

@danmm7 What's you idle voltage with new alternator?.

FYI, it's a 2007 GX470 with 106k miles


Update: Based on further research on 2UZFE V8 engines with 100/130 A alternator's, 13.6v is normal, they don't need 14.2v because amperage is higher.