F350 Idler pulley....

[John T]

Funny, the other day I commented my truck never gave me any problems... karma I guess.

Anyway,
I started the truck today and hear something clank off the fan blade...
Immediately shut it down and found the top idler pulley came forward and fell OFF the bearing...

This is the single smooth pulley right above the tensioner assembly (serpentine belt)

The bearing seems to be good... I replaced them all not too long ago.
the Timken sealed bearing presses into the pulley.

Seems like a tight fit when you press or tap them in. kind of odd that it came off.

One thing I noticed, This pully does not have any lip on the backside to keep the pulley from coming off the bearing.

I had a spare tensioner pully and compared it... the tensioner pully has a lip on the backside (pics)

They look to be almost identical size... maybe a few mm's difference.


I might try the spare tensioner pully or use a thin flat washer on the back of the pulley to prevent it from happening again... OR stake it with a prick punch...

I could probably use green loctite on the bearing also... even though it seems to fit tight.

Years ago, I DID have a bearing fail on the tensioner assembly busting the belt.
I replaced the bearing and has been good since. and like said, I replace those bearings everytime I change a belt.
MAYBE the tensioner itself is going bad... the internal spring?
But the belt looks OK ....

Could the recent Arctic freeze/thaw cycle made the pully expand/contract and break the press fit?

I'm rambling now....
As soon as this coffee cup is empty and the dogs evacuate I think I'll try the pully with the lip on the back and have a good 'look-see'

I've had bearings go bad... but NEVER heard of this happening. to anyone.

 

[William1]

I'd also consider... what force was present that made the pulley want to walk off. All being in alignment and square to one another, nothing should want to move.

 

[GreensvilleJay]

hmm... I've seen 'flanged' bearings on snowblowers, maybe there's one to replace that 'normal' bearling ?

 

[John T]

I installed the spare pulley with the lip on the back and I'm back in business .... belt is running true.

I only found one guy on the powerstroke site that had the same exact thing happen.

unknown phenomenon ... ? They say everything happens for a reason....
full moon?

 

[hagrid]

Some stud and bearing retainer from the good folks at Loctite would solve the issue with all finality.

 

[John T]

Some stud and bearing retainer from the good folks at Loctite would solve the issue with all finality.

Until you need to replace the bearing...

But I hear ya... I have used a similar loctite for press fits...

 

[William1]

I too, would use some red or green Loctite.
A torch and a press would get it out later PDQ.
I have to wonder if the bore of the pulley was square....

 

[lynnmor]

There is a strange wear pattern on the belt. I would indicate the outside to see if it is tapered, if so grind it true or replace it.

 

[hagrid]

There is a strange wear pattern on the belt.

Thems "tork stripes".

 

[TheOldHokie]

Until you need to replace the bearing...

But I hear ya... I have used a similar loctite for press fits...

Loctite 641 - shear strength 1700 PSI.

But a tiny drop on the outer ring and spread it axially with a finger tip. Repeat at 180 degrees. It will secure the bearing and come apart without any fuss.

The more surface area you coat the harder it will be to disassemble.

Dan

 

[hedgerow]

I ran one of those engine over 300,000 miles and never had that happen but I always loctite those bearing in. Just finished up a JD 8420 tractor changing belts and put a couple bearings in some idler's and loctited those bearings in. The last thing I want is a idler going threw a five to seven thousand dollar radiator. I can deal with getting the bearing out next time because of some loctite.

 

[McMXi]

Funny, the other day I commented my truck never gave me any problems...

What year is your F-350? I occasionally hear a squeak at start up from the equivalent pulley in my F-250 which is a '02 7.3L model with 180k miles on it.

 

[John T]

I always loctite those bearing in. Just finished up a JD 8420 tractor changing belts and put a couple bearings in some idler's and loctited those bearings in.

Interesting...

I must say Until this happened I would never have even thought of that.

I will NOW.
Thank you.

 

[John T]

What year is your F-350? I occasionally hear a squeak at start up from the equivalent pulley in my F-250 which is a '02 7.3L model with 180k miles on it.

1995.

Yes, The 'squeak' is a tell tale sign of a pulley bearing getting ready to go south.

Bearings are easy to swap out... mine use Timken 6203-2RS

they are probably all the same... but don't quote me on that.