It finally happened. The timing belt snapped...

[gnu]

Originally Posted by trikey

You have just contradicted your own theory there, if the polymer technology has advanced in the last 20 years, then surely the plastic tensioners would be a little better by now?

Polymer, I was meaning the belts.

I assumed the tensioners, although containing some plastic, are built around metal bearings, which wear.

[bl52krz]

Originally Posted by SD1too

Remember Andy that MGR doesn't specify an interval for the "ancillaries" (the tensioner and idler pulleys) at all and they are the cause of the rare failures! So much for MGR's position. The belts have been proven to last in excess of 90,000 miles easily. As several KV6 owners have agreed in this thread, the MGR 6 years schedule is a nonsense.

Simon

I am sorry to disagree on your point of it ‘being nonesense’ Simon. I think that the original 6 years was a ‘safe mode’ response because of warranty claim possibilities.I have always erred on the safe side of servicing of vehicles that I have owned. Wrong decision when I changed the drop links on the diesel for that reason.They only did around 4000 miles.

[rab60bit]

[QUOTE=gnu;2841795][QUOTE=trikey;2841786]

Originally Posted by gnu

I think polymer technology has come on a way since the service schedules were set out for many older cars.

However I do agree that the tensioner pulley is a weak link.

Polymer, I was meaning the belts.

I assumed the tensioners, although containing some plastic, are built around metal bearings, which wear.

It's the plastic that 'goes', not usually the bearings; if you get a chance just take a look at one that's done say 35-40K, there are cracks all over the place.
DMRGS on here offers I think an improved idler, not sure how it's improved but an all steel one would be a move in the right direction.

[gnu]

I fitted a DMGRS one to my 25 a few months ago and kept the old tensioner, so I’ll have a closer look at the plastic bits when next in the garage. As I said before, I recently chucked a 60k one with rumbling bearings, I didn’t note any plastic degradation, although I wasn’t aware that was an issue with them.

[SD1too]

Originally Posted by gnu

I do this all the time. See what is advised, apply my own knowledge and experience and decide what to do.

A perfect summary!

Simon

[BaroqueMoon]

She's beautiful, even on the back of a tow truck.

https://photos.google.com/album/AF1Q...c_TkwOVzKpAhYE

[DMGRS]

If you can do the work yourself, I'll do the best deal I can on the belt kit and the full timing tool kit - you'd probably be able to sell the kit on to someone else over there too.

Drop me a PM if I can help.

[sworks]

Originally Posted by gnu

I do this all the time. See what is advised, apply my own knowledge and experience and decide what to do. Usually works.

Are you saying you wouldn’t replace the pulley if it’s not in the MG schedule?

I’m not sure if this was aimed at Simon or me so I’ll answer wiith my point of view. I was pointing out that a lot of manufacturers don’t actually state that when the cambelt is due you should also change the associated parts. It was the part suppliers that started batching things into a kit years ago.My opinion as most know is to adhere to the manufacturer guidelines and fit all associated parts. The last V6 cambelt change I did consisted of the belts, tensioner, idlers, the hydraulic damper, caps and cam sprocket bolts etc not forgetting the water pump

[Avulon]

Originally Posted by SD1too

Hello Matthew,

First of all my deepest condolences. Despite the fear associated with this, it's still very rare. But more importantly, the cause won't be belt failure, that will be the result of something else.

You might have read that, when I changed them, my original belts were 19 years old and had covered 90,000 miles. I was surprised to find that they displayed virtually no wear and tear however, the tensioner and idler pulleys were in need of replacement.

I'd be interested to know the mileage of your car because if it has suffered pulley bearing failure (leading to belt detachment), that information will be a very useful guide to other KV6 owners.

Once again, I'm very sorry to hear of your predicament. Hopefully the damage can be repaired.

Simon

Simon, I really find it amazing that you continue to equivocate over this. The belt failed, period. You may be right that the belt failed due to wear and tear in associated parts - tensioner, idle pulley, whatever. But to say that the belt didn't fail, something else did isn't really any help. If the belt had been changed anytime before this catastrophe by a competent mechanic then the other parts would have also been changed. To distinguish a belt change from a belt and idler and tensioner and even waterpump change is pointless. No-one would ever do one without the other if they know what they are doing. I think what you really want is for the service manual to say - change the pulleys at 6 years/60k - (and while you're the there change the belts anyway). Well it's not getting re-written now is it?

Originally Posted by rab60bit

Sorry to hear it.
Happened to me with my first 75, a 2L KV6 (1999 SE) that I purchased with very little history. I think it had been reasonably well looked after but I didn't know much about 75's then!! I've commented on here before regarding timing belts and I'll say again - the belts will safely do far more than the 60-90K/6 years, more often than not it's the idler that's the culprit - same difference/result, it bu...rs the engine.
Take your time and it's a doable DIY cheapish job providing you've not goosed the valve gear etc.

Exactly - same result whatever component is to blame. If the belts were done then the other bits would be done as well.

Originally Posted by SD1too

Thanks Matt. That's 100,666 miles. Given that my tensioner and idler pulleys were very rough at 90,000 miles, my guess is that one or both of those were the cause. It's helpful to know that they didn't go a lot earlier. Thanks for the information.

Simon

Perhaps Simon you would change the idler pulleys and tensioner without changing the belts?

Originally Posted by SD1too

Hi Andy,

Because it's not playing Russian roulette. The real required times are evident from this thread and others before it and they're not 6 years! Something like 60,000 miles for the pulleys would be a sensible figure (and do the belts at the same time).

Simon

Originally Posted by trikey

Well it does seem that a bullet has been fired from what the OP said, lets face it, if the belts and ancillaries had been changed at MGR stated intervals then the engine would be in a better state of health than it is now.

Well said.

[rab60bit]

Originally Posted by Avulon

Simon, I really find it amazing that you continue to equivocate over this. The belt failed, period. You may be right that the belt failed due to wear and tear in associated parts - tensioner, idle pulley, whatever. But to say that the belt didn't fail, something else did isn't really any help. If the belt had been changed anytime before this catastrophe by a competent mechanic then the other parts would have also been changed. To distinguish a belt change from a belt and idler and tensioner and even waterpump change is pointless. No-one would ever do one without the other if they know what they are doing. I think what you really want is for the service manual to say - change the pulleys at 6 years/60k - (and while you're the there change the belts anyway). Well it's not getting re-written now is it?






Exactly - same result whatever component is to blame. If the belts were done then the other bits would be done as well.





Perhaps Simon you would change the idler pulleys and tensioner without changing the belts?









Well said.

Simon is trying to emphasise that the 'official' servicing information (being generous - from 2005 - because the servicing data is probably quite a lot older than that) only addressed replacing belts; the OEM therefore implies the belts alone were considered suspect at 6 years/90K whatever....logic, weakest link in a chain etc.
'We' now know from +10 further years empirical experience that the OEM should have recommended a 'drive belt system' replacement schedule because other components/assemblies within that system were suspect/inadequate (our marque guru's know this, mere enthusiasts may not) but the OEM had a market to address and adding perhaps £1000's to running costs would not look good in the motoring press etc.
I seem to recall that the mass production automotive industry used design parameters for non-consumable component life calculated at approx. 250K miles if the service intervals were observed - in other words, if all things were equal they'd/you'd expect to throw your car on the scrapheap after 1/4 million miles (thus a mean 15K/annum = 16 years) faithful service.