RedCher

I have an 02 Cherokee Laredo Sport. It has 118000 miles on it and she runs great but recently I've noticed a burning belt smell. I've checked the belt and it looks fine. What else might be the problem? Thanks ahead of time.

RedCher

go-part

Chances are it is a seized tensioner or idler pulley.

wiggles

I would remove the belt and check each pulley for proper function

RatchetMaster10

I would personally look for a leading valve cover gasket on the drivers side where the oil could be running down onto the exhaust manifold. If any of the pulleys for the belt locked up, the belt would squeal incredibly loud and would snap within a few minutes of not immediately.

RedCher

Thanks for the responses. Ill check all those and see what I find.

dave1123

About oil on the belt. I know from experience, if you spill oil on the belt while it running, the belt will rapp you up 'aside the head!

I'd go with a idler pulley bearing dragging.

RatchetMaster10

Not saying oil on the belt. Saying oil on the exhaust manifold. Anything seized up that bad in the belt drive will in fact destroy the belt in a matter of seconds.

Noah Wallace

Hope I'm not hijacking this...

I Had the burning smell and humming noise last night. I noticed the idler pulley wasn't turning so I replaced it. All the pulleys are turning now but there's still a humming noise and burning smell, possibly coming from the alternator or ac compressor. The alt was replaced less than 18 months ago.

Also when I first noticed this last night, the battery gauge was all the way down but power steering, etc was all still working fine. Now the gauge is higher but sill a little low. Perhaps the battery took a little hit during the islet pulley seize? Either way, I need to know what to look for next.

I'm stumped, please help me!

dave1123

Remove the belt and spin the alternator pulley with your hand. It should spin freely without any noise or resistance. It not, you've found the problem.

It's possible the brushes are worn in the alternator and causing a reduction in voltage output. The brushes send power to the rotor making it a spinning magnet. This induces a current in the stator windings. The PCM controls this magnetic field to produce the discharge voltage and current. Most of the reasons alternators fail is because of worn brushes or failure of the bridge rectifier, but in most cases it's brushes. Worn bearings can make the brushes bounce, reducing the output. Unless the field windings are toast, you can usually repair an alternator, but most people don't. A good automotive electrical shop can repair your alternator cheaper then buying a new one.

Noah Wallace

Yeah, I did that and all the pulleys turned by hand

dave1123

Read my last post, edited while you wait!

blueseasons

When my alternator brushes needed replacing I bought one off EBAY for $8 and installed them myself. To have the alternator rebuilt locally was close to $300. A rebuilt one was over $200. When I asked the local parts supplier about the rebuilt ones he said: "we have better luck with the DENSO". Given I didn't want the reliability of a 200 dollar alternator based on luck, I just replaced the brushes and so far I have been lucky, at a much lower cost.

dave1123

Smart! I used to rebuild GM alternators for my friends, but parts started getting hard to get from parts houses. In my case the rectifier bridge and diode trio were the same in any GM alternator, just the brushes were different in the larger output ones. Your guy is right about Denso.

Bearings are easy. I'd rather replace a $4 bearing than buy a rebuilt alternator.

My brother ruined a perfectly good 90amp GM alternator by running the pulley nut back on with an impact wrench! It...was...crossthreaded!! Familiarity breeds contempt!

blueseasons

I have not totally rebuilt an alternator, but I used to replace bearings and brushes in the generators in my old Chevys. I don't know how long the bearings will last on the DENSO alternators. I should have done them when I had mine apart, but I didn't realize brushes were so easy to do. I figured if I got that far, I could always go back and do the bearings at some point. I don't have a puller either, but it seems to be holding up.