Play on serpentine idlers

[Crispin]

Folks,

For a while now I have had a growl (unhappy bearing) sound coming from the front of the engine / serpentine belt area. Mr-T suggested replacing all the tensioners and idlers to see if that stopped it. This would have cost a shade over 500 in parts

I've just taken the belt off and checked each of them (in situ). The tensioner seems fine. Nice and smooth but does not feely spin, zero play on it. The two idlers though have some back and forth play. not a huge amount but enough to see it move. There is nothing though against the axis. Floating on the axis slightly would describe it.

Would this be normal? Both are smooth, don't freely spin etc but there is a small amount of play.

Could this be causing the unhappy bearing sound? Would a failing bearing not also introduce some up-down play as well?

At just over £100 an idler, I would rather not change them "just to see"

Answers, as always, on a post card

 

[Graham]

Hi Crispin,

Perhaps start off and change the one you feel is the possible suspect?
Then drive it for a week, and see if it was the one.
If not, then go for the next most likley suspect?

What miles has yours got now?

Graham

 

[Crispin]

Hi Crispin,

Perhaps start off and change the one you feel is the possible suspect?
Then drive it for a week, and see if it was the one.
If not, then go for the next most likley suspect?

They both have the exact same amount / type of play on the which is why I was wonder.

What miles has yours got now?

Graham

Mine has normal miles on it. Think it is standard? 1.6Km to a mile.

It has 98800 miles on the clock.

 

[Paul]

You normally get a little play in them with no worries.

Do you get the noise as soon as the engine starts up? If so, why not run engine with the belt off to try and isolate the noise, might not be the idlers.

 

[Rob]

I would start with the tensioner as is should spin freely. It is normal to have a tiny amount of play in deep groove ball bearings due to bearing internal clearances. This is internal clearance play is easier to detect as axial play rather than radial play which is what you are describing.

 

[Jon Wildsmith]

Did you feel for roughness in the water pump, alternator, air-con compressor etc as well to rule those out? The idler/tensioner bearings should run smooth and free IMO, if they feel a bit stiff I don't think that's right and possible if they were off the truck you'd be able to feel some roughness in the way they turn more easily than with them on the truck.

 

[Crispin]

I did not actually check them.

/walks off to get the spanner for another look

 

[Nuclear Chicken]

Did you feel for roughness in the water pump, alternator, air-con compressor etc as well to rule those out? The idler/tensioner bearings should run smooth and free IMO, if they feel a bit stiff I don't think that's right and possible if they were off the truck you'd be able to feel some roughness in the way they turn more easily than with them on the truck.

Crispin, when I changed my aux belt the idlers and pulleys were as Jon describes. All easy to spin but no noticable play at all, axial or radial. All spin easily. There's just too much tension on the belt for any discernible play. i.e. tolerances are tight. If you have one as described that won't spin easily then suspect it's suspect, if you know what I mean. My mileage at the time was 93k I think, so just about the same as yours. Only brand new ones are a bit stiff till they get a few thousand revs on them.

 

[Crispin]

Sorry, I meant to reply to that -
They are not stiff but rather feel like a bearing with grease in it if that makes sense. (or maybe they should be freer?) if I spin it (as best I can in the engine bay) it does about 1/4-1/2 a turn before stopping.
Considered stiff?

I did not get a chance to look at the other bits yesterday, will have to wait for the weekend (dark when I get home... )

 

[Jon Wildsmith]

Considered stiff?

Yes

 

[Rob]

[quote="Crispin":2739ycqk]Considered stiff?

Yes[/quote:2739ycqk]
Agree but a new one may be just as stiff until it beds in