Narrowing down a whine/grind the hard way

[LX101North]

I've been throwing a bit of money at this whine/grind noise for about a month or so now. I replaced the water pump which oddly enough started spitting at the same time as the suspect noise. All timing pulleys were replaced. No change. Then I replaced the drive tensioner pulley. It sounded and felt like it needed to be replaced. I rebuilt the power steering pump and flushed with synthetic. No dice. I then replaced the drive idler pulley. It needed to be replaced anyways. Thing have gotten quieter which have really made it evident that the sound is still coming from what would have to be the alternator. I took the drive belt off and started the engine and it was perfect.
Tonight I drove the rig and when I got home it was whining loud as ever. I turned off the headlights and the pitch of the whine changed drastically. Turned lights back on and it got really high pitched again. Alternator failing? Any thoughts? No big symptoms yet.
Thanks!

 

[adrenalinefjz80]

The alternator bearing is on its way out likely. The only bearing left you haven't replaced is the fan bracket assembly from what you said. Also, the transfer case whine in colder temps sounds different with deeper pitch.

 

[LX101North]

The alternator bearing is on its way out likely. The only bearing left you haven't replaced is the fan bracket assembly from what you said. Also, the transfer case whine in colder temps sounds different with deeper pitch.

Yeah. It's kind of what I was thinking. It's definitely not the fan bracket. The noise is coming from PS down low and like I said, I did take the belt off and started it up. Smooth as butter. We took it off road this weekend and performed really well....except for the noise. Hmmm. Is it time for the mean green alternator upgrade? Are they an upgrade?

 

[hoser]

Dates are approximate:

98-99 have 80A alternators. 00-02 have 100A and drop right in. '03+ has 130A but needs a change in connector to work with earlier years… which isn't too hard.

I ended up going with the 150A Sequoia alternator and added a larger charge cable (plus change in connector). I've been told all the LC100 alternators are remanufactured but the Sequoia ones are available new.

I would also consider taking your existing alternator to a shop and having them rebuild it.

 

[adrenalinefjz80]

I bought the 100 amp when I replaced mine not knowing which it had originally. It was indeed a 100 amp installed from the factory.

 

[hoser]

Yes, ordering a replacement alternator for a 98-99 from the dealer will get you the 100A.

 

[ENGINE er]

Instead of throwing parts at it go buy a $20 stethoscope from the auto parts place and narrow it down.

Mynoise was coming from the fan bracket bearing. Narrowed it down pretty quick with the stethoscope.

 

[LX101North]

Dates are approximate:

98-99 have 80A alternators. 00-02 have 100A and drop right in. '03+ has 130A but needs a change in connector to work with earlier years… which isn't too hard.

I ended up going with the 150A Sequoia alternator and added a larger charge cable (plus change in connector). I've been told all the LC100 alternators are remanufactured but the Sequoia ones are available new.

I would also consider taking your existing alternator to a shop and having them rebuild it.

Are they really that hard to rebuild myself? I've never opened done up, but I'm not really lacking confidence in doing so, if the job was possible for an amateur/fast learner.

Instead of throwing parts at it go buy a $20 stethoscope from the auto parts place and narrow it down.

Mynoise was coming from the fan bracket bearing. Narrowed it down pretty quick with the stethoscope.

It's time to definitely get a stethoscope. The screwdriver I have probably isn't cutting it for what I need. In my defense, all those parts won't have to be replaced for quite some time now...haha!

 

[hoser]

I've never done it either but the FSM outlines the rebuild and it doesn't look difficult. But upgrading the output is one reason I would send it to a professional.

 

[APKhaos]

Are they really that hard to rebuild myself? I've never opened done up, but I'm not really lacking confidence in doing so, if the job was possible for an amateur/fast learner.

The FSM procedure is clear, and its no different to rebuilding any basic electric motor. Replace both bearings carefully. Pressing the old bearings off and the new bearings on without damaging the bearings is the skillful part.

It's time to definitely get a stethoscope. The screwdriver I have probably isn't cutting it for what I need. In my defense, all those parts won't have to be replaced for quite some time now...haha!

The next best thing to a stethoscope is a simple length of 1/4 or 3/8 vinyl tubing that you can pick up at most hardware stores. One end in your ear, the other searching around for the source. You'll be surprised how well this works.

 

[LX101North]

I've never done it either but the FSM outlines the rebuild and it doesn't look difficult. But upgrading the output is one reason I would send it to a professional.

An upgrade would be a good thing for sure. I didn't know that the alternators have kept getting better through the evolution of the 100.

The FSM procedure is clear, and its no different to rebuilding any basic electric motor. Replace both bearings carefully. Pressing the old bearings off and the new bearings on without damaging the bearings is the skillful part.



The next best thing to a stethoscope is a simple length of 1/4 or 3/8 vinyl tubing that you can pick up at most hardware stores. One end in your ear, the other searching around for the source. You'll be surprised how well this works.

I have some tubing. Trying this today. Thanks man!