How to adjust alternator belt on 1999 Lexus ES300?

incorrect on two counts:

1. rubber has a positive linear thermal expansion coefficient, not negative.

1. belts are not simply rubber - they have longitudinal aramid/glass fiber reinforcing that dominates their linear properties.

1. the alternator belt is not a timing belt.

1. your belt has not stretched [see #2 above], it has simply worn. this is common in cold climates where alternator loads are higher, especially on startup. simply adjust or replace.

no, serpentine means it has a run with rollers on both sides of the belt, not just one - it loops back on itself. multiple components can still run on a non-serpentine belt.

Replace if its near time, its worn. Its not the timing belt, but how old are both, maybe both are overdue for new ones.

condor snipped-for-privacy@yahoo.com wrote in news:0f597bb2-4c78-4978-b780-d000f887b0f4 @o3g2000yqb.googlegroups.com:

Identical, actually.

That's Canada for ya. Too cold. Way colder than, say, DC just now...

It shrinks, like anything else.

It also gets /harder/ and s/slipperier/, which you're misinterpreting as expanding.

T'ain't a timing belt. It's an accessory drive belt.

The secret is: one bolt above the alternator and two underneath it. I think they're all 14mm, but I'm not certain.

The one above (points to the SIDE) must first be loosened slightly.

The one below that points towards the SIDE of the car (same as the one above) also needs to be loosened.

After that, you turn the one below that points to the FRONT of the car until the alternator belt has the right amount of tension. Clockwise will tighten.

Then you snug 'em all back up again. Piece of cake.

I don't know what Ford you had, but my Fords have a spring loaded tensioner that never needs adjustment.

Me thinks your Toyota might be the same.

No, a serpentine belt transfers power from the crank pulley to all accessory drives.

Yours is an alternator/AC belt. You also have a power steering belt. This setup is an old jack screw (for Alt/AC) and slide rail (for PS) adjuster design. It's cheap and clearly doesn't try to main proper tension automatically as in those serpentine systems using automatic tensioners.

So as described, you need to loosen the lock bolts and pivot bolts and either turn a jack screw or use a pry bar against the PS pump to adjust tension. Ideally, you'll need a Krikit-II gauge if not a more versatile tension gauge. The Krikit-II is about $20 on Amazon.

Must be a 1908 Model T. :D

No, Yota uses cheap jack screw and slide rail tensioners.

Short answer: You need a new belt and maybe the tensioner too. You can't adjust anything to put more tension on your old belt, it is stretched for sure and the spring in the tensioner has probably relaxed some too. Just replace them.

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You probably already googled this but here it is just in case you didn't,

I remember there were rubber band "engines" run by heat. And those "rubber" bands did contract when heated. Now, I dont intend to go back and research all this, but, IIRC, there is a whiff of truth in the basic statement.

Let's just say that there are rubbers (latices) and elastomeric compounds which we call rubber.

I am interested in the concept, but not enough to make an issue of it.

BUT, his concept is flawed. The problem is almost certainly a worn or improperly tensioned belt.

for some temperature ranges, yes indeed. but the belt our friend was describing doesn't experience that, partially because it's not that kind of "rubber", but mostly because of the reinforcing fibers.

Right, it's not a timing belt. My bad. Good catch.

Thanks for the detailed instructions. I appreciate it! I'll see if there are tools around to do it on my own.

Some misunderstandings about rubber and cold.

I'll make another post about what really cold weather actually does to cars in the winter.