Marks DTM Calib wrote on 14. Dec 2009 at 11:13:

Thats re assuring.
On reading this thread i went directly to the garage to check my old cam belt kit,( havent got round to throwing it out yet), to take a closer look at the tensioner bearing as i remember seeing some grease thrown out due to centrafugal force.

It showed grease from the inner most edge of the seal escaping as lines radiating out from the centre ,as it would. All 3 bearings show the exact same thing. Presumed it to be normal esp after spinning the bearings. Still some stiffness left in them esp. as the grease was cold in the garage last night, not quite freezing.

I fully intended to check my belt after a year or so, just to check the timing on bank 1 and 2 to see if it settled in and retarded a fraction from where i set it and that the tension is still correct. Wouldn't do any harm, if i ever get round to it.

Ps not much comfort to the op tho. Sorry to hear
this Gary.

it happens mate. Even chains fail early.

Warranty worth persuing, tensioner itself "should" be evidence enough. Easy sitting here though.

ffcgary1 wrote on 15. Dec 2009 at 18:54:


Thats little more than an inference based on little evidence.

Given its a standard bearing design and from a reasonably regarded supplier plus there are 100's of millions of this type of bearing on loads more different applications......I would infer thast not the cause.

It could be so many things that caused it.......

ffcgary1 wrote on 16. Dec 2009 at 17:31:


Lets look at the mechanics of what is happening (note, this is so we all understand why bearings are constructed how they are and to give further insight into why we see grease).......the bearing is made and packed with grease, they err on the 'to much' side knowing that any extra will be forced out as this is a much safer approach than to little.

Plus its not possible to guarantee exact delivery of the 'perfect' quantity due to real life manufacturing tolerances.

Seals are fitted and then during running, the extra grease is forced out.

The key thing to note is the seal design, its fitted to the outer race and runs against the inner race, hence centrifugal force forces the grease to the outer race...this is not a problems as its a sealed face and as the balls within  the bearings rotate they are re-lubed.

Any grease that exits comes through the small gap between the inner race and seal and exits outwards towards the outer race section (you can see this as lines of grease).

There is no fundamental design floor in the bearing make up. 

Again, my apologies, the above post was me 

ffcgary1 wrote on 16. Dec 2009 at 17:31:

The seals will not keep grease in the bearing if the bearing overheats, or if it starts to fail for any other reason eg overloading. once it starts to wear, the Grease will be expelled as the seal will no longer be effective. rapid wear will then ensue and may make it seem like worn seals were the cause of the failure rather than just a symptom of it.

I recently changed the belt kit and waterpump on my
4 pot and was a little surprised at how many times
I had to hand wind the engine over to settle everything.
I had to set and retorque the tensioner 3 times before
it would hold the correct tension, and this was with
turning the camshafts through at least 4 revolutions
between each retorque.

The first attempt the tensioner lost all its tension, the
second time it lost half its tension and the third time
it remained correctly tensioned.

The belt is under its main tension loading on the length
on the right hand side where the crank is pulling against
the load of the camshafts via a single idler pulley.
When it comes off the crank on the left hand side
it is relatively idling around the tensioner, idler and
waterpump so this is where any slack needs to be
taken up as the belt is in a relatively relaxed phase
in comparison.

As said, I had to handwind the engine over so many
times to condition and settle the belt I was bloody
cream-crackered when I'd finished. 

I intend to whip the aux belt and cambelt cover off
when I've done a few more hundred miles and recheck
the tension and timing. That is if I've still got it by then.
Mrs Grumpy has her eye on a Merc C class Sporthatch
that she's trying to talk me into lobbing the Omega in
against on a part exchange deal. All that extra money
for an inferior car.