How to check belt tensioner?

Question

'98 Explorer with 5.0L engine, 115K miles. Serpentine belt started chirping at start-up in cold weather. Driving through puddles with cold engine makes it worse - a deep puddle caused it to slip so bad that I lost power steering until the belt dried up -- bad deal! Couldn't do much about it, because it was away from home. Now back home, I am looking and everything appears normal. Tug on the tensioner, and it returns smoothly. Belt looks fine - no glazing or anything. I am thinking that the tensioner is weak, but how can you tell? FSM is moot on this. My ancient belt tension gauge shows about

75lbs, which seems very low to me, but there is no tension spec. I can see a mark on the tensioner saying 'LIFT' and a groove against it. Is the mark supposed to be within the groove? Mine is just past it. No experience with this spring-loaded type of tensioner. Help appreciated -- thanks!

Big Shoe · Accepted Answer

If you still have the original belt in a '98, I would replace itbefore even considering whether there is a tensioner problem as well.

newman · Answer

when should you change the belt.  my 2000 has 86K miles.If you still have the original belt in a '98, I would replace itbefore even considering whether there is a tensioner problem as well.

Ulysses · Answer

Probably about now.  According to what I've read "cracks" are acceptable.Small missing portions up to about 1/4" are OK.  Missing portions next toeach other are NOT OK.

Ulysses · Answer

I just have the 4.0L engines but in order to move the tensioner I need to use a two foot long cheater bar. Can you move and hold yours with only a

3/8" rachet wrench? That might indicate a weak tensioner.

The only other thing I can think if is the belt is too long. I've read in the past of some people getting new belts that were just a little too long.

My Hanyne's manual has a picture of "belt wear indicator marks" on the side of the tensioner body. It's not clear to me if the marks indicate stretch or just plain loss of rubber. I did not see any marks on my tensioner.

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Happy Traveler · Answer

Update: there was no indicator on the tensioner; at least not one that I could see. But the belt was dry, stiff, and stretched about 1" (compared to a new one that I just installed). So far so good. Thank you Big Shoe!A couple comments:1) If the tensioner has moved out range (which I could not tell), it's not the tensioner's fault, but the belt has stretched.2) Used the KD 'GearWrench' tool to relieve the tension. It has one of those micro-ratchets for fine tuning of the angle. Not sure about longevity, but using this thing made a pleasure out of an otherwise knuckle-scraping job, especially in the tight space of the 5.0L  (found it on sale at Sears for $15 less than the online Tool Source price).

How to check belt tensioner?

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