Belt tensioner spigot worn

[snowwolf]

Thought I would change the serpentine belt this eve and noticed play in the pulley, removed the pulley expecting bearing to be shot but was ok, the wear is on the spigot where the bearing sits and is worn by half a millimetre, bit of a bad design as the spigot only protrudes 8mm and the bearing is 12mm thick so there is not a great deal of surface area that the bearing sits on.

I have two options, buy a new tensioner from the guys that sell the TVS 2300 SC's and have it fail again after 40K miles. which is not bad really or build it up with some ally welding and machine it back to the 17mm spigot that the bearing sits on.

If you have this 2300 set up get hold of the pulley and feel if you have any movement when you twist it from side to side, you can do the check while the belt is on the pulley.

[stevieturbo]

The only way that could wear down is if the pulley bolt wasnt tight, or the bearing seized and spun.

That part of the tensioner is not something that should ever wear at any mileage.

[snowwolf]

Bolt was really tight, bearing was fine too, unsure why it has worn, only thing I can think of is how short the shaft is, its only 7mm long (just measured it) bearing is 12mm you would expect the shaft to be at least 11mm

[Black VXR]

Perhaps it was like it when fitted

[Boosted LS1]

Or the tensioner itself has been moving more then usual or had stronger loads imposed upon it. Belt misalignment could have been an issue.

[snowwolf]

I have had another look today and the bolt looks like it has bottomed out in the thread, it was just enough to tighten up a fraction on the washer as it bottomed out, so the inner race of the bearing could spin when under load wearing the spigot down.

Monkfish came to the rescue with a new uprated tensioner that is fitted to the TVS2300 and should be with me tomorrow, cheers Roger

If you have the 2300 set up it may be worth checking before you end up with a problem.

Edited by snowwolf on Tuesday 1st July 13:02

[snowwolf]

Just to recap, new tensioner arrived ok, cheers Roger, measured the spigot and same as old one 16.5mm bearing is 17mm so has half a millimetre play, the bolt that holds the bearing in place does bottom out on thread but only the last 2mm not really a problem, its cast ally so just cuts into it and tightens up against the bearing ok, think its just how they are made, the play in the pulley is same to, just the nature of single ball race bearings, I will fit new tensioner as the old one has done 40K miles and may be feeling a bit tired, and it does drive the supercharger so probably best to change it.

[preciousmetal]

Mick. You seem to have a thing for changing idler wheels and pulleys !!

[snowwolf]

preciousmetal said:

Mick. You seem to have a thing for changing idler wheels and pulleys !!

LOL not really PM had a squeaky tensioner pulley a while back, but at the time didn't notice how loose the bearing fits on the spigot ( in my line of work I am used to much more finer tolerances ) only when changing the belt the other night I noticed what was mentioned above, couple of years back had the air compressor tensioner mod done as it kept throwing the belt off, I do like to maintain my car and touch wood its done 63K trouble free miles

PS you have got me worried now as I have never changed an idler wheel

Edited by snowwolf on Thursday 3rd July 20:55

[stevieturbo]

snowwolf said:

Just to recap, new tensioner arrived ok, cheers Roger, measured the spigot and same as old one 16.5mm bearing is 17mm so has half a millimetre play, the bolt that holds the bearing in place does bottom out on thread but only the last 2mm not really a problem, its cast ally so just cuts into it and tightens up against the bearing ok, think its just how they are made, the play in the pulley is same to, just the nature of single ball race bearings, I will fit new tensioner as the old one has done 40K miles and may be feeling a bit tired, and it does drive the supercharger so probably best to change it.

Use a more suitable bolt, or stick a washer or two on it. The bolt must be properly tight or the same thing will happen again.

Shouldnt really be any play worth talking about.