[ds968]

Is there a manufacture date printed on the balance and timing belts ( Gates, or otherwise ) ? The reason for the question is how does one know that the " brand new " belts you buy have not been in stock / on the shelf for five years, or ten years, or even twenty years ?

Partial Post: Please Login or Register to read the full post.

[tamathumper]

Can't recall if there's anything on mine, although any printing on the double-sided belt would probably quickly disappear. Interesting stuff - a belt should be good on the shelf for 8 years according to Gates. IF it hasn't been hung over a peg, gotten too hot or cold, etc... In addition to the born-on date, it seems knowing the storage conditions would be the trick.



http://www.gates.com/facts/documents/Gf000280.pdf

Partial Post: Please Login or Register to read the full post.

[flash]

i've been looking for that sheet for a couple of years now. thanks!!! i thought it was 10, but it's 8 - sweet!!!



of course, now we're going to hear from all the people who have had their belts on there for 15 years and "never had a problem". i love that one. yeah, i've never been hit by a bus either, but i'm not stepping out in front of one



it does beg the question though as to how old the belt you buy is. i'll look at some packing i have and see if there is any sort of date on any of them

Partial Post: Please Login or Register to read the full post.

[ds968]

this scares the heck out of me ( having had a timing belt failure and the ensuing $ 6 k job that came with it.. <img src="/forum/images/smilies/968/glare.gif" class="smilie" alt="" /> ) because I'm not sure Gates or anyone else controls and/or enforces the 8 year "rule" with their distributors / dealers that sell the belts. and since next summer it will be 4 years since my last change ( though I've only put a pathetic 10k miles on the car since then..) it's time to replace them and really don't want to end up with anything that's already a decade or even more old, no matter how ideal the storage conditions they have been in..

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

On a related note, I have a significant concern over my particualr situation. I bought a new set of Gates belts at the start of my project back in April of '11, and I have no idea as to their shelf life. But then the project dragged on much longer than I expected, and I finally put the belt on in April of this year. But other non-engine related projects, and non-968 related distractions, have delayed my finishing everything up to the point where I'm ready to fire it up. So, the belts have been sitting on the engine, in the case of the timing belt under the full tension of then tensioner, motionless, for nearly five months. Should I worry? Should I tear it apart again, throw the existing timing belt away, and install a new one, before I finally fire it up? Seems like overkill, but then again, I have a huge investment of time and money in this thing, and having it all go kaboom would really ruin my day.

Partial Post: Please Login or Register to read the full post.

[flash]

how much would the bottle cost that you would have to buy to get over the failure?



belts should never be allowed to sit under tension for extended periods. if you have an engine with belts on it that has to sit, always go out and rotate it periodically

Partial Post: Please Login or Register to read the full post.

[tamathumper]

I believe that same manual says that belts should, ideally, be detensioned if they're going to sit for six months. I'm not sure I'd do that, though - have you ever wondered how busy you would be if you followed every manufacturer's recommended maintenance regimen? You'd be lubricating the axles on your lawnmower, cleaning the door seals on your refrigerator, polishing your chrome kinaedor valves,...



Given that our tensioner is hydraulic, does it remain under full tension when the engine isn't running?

Partial Post: Please Login or Register to read the full post.

[flash]

lol - i do clean the door seals on the fridge

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

Sigh. Yes, it has crossed my mind at least ten thousand times since I installed the belts that I should go rotate the engine periodically. So how many times have I actually done it? Not sure of the exact number, but it's approximately at, oh, I don't know, maybe Zero.



I think I'll start rotating it, see how lucky I feel, and then decide whether I want to replace it. At least it's been warm during the period it's been sitting under tension (which I guess is a good thing...)



But as I think about it, how many people store their cars for extended periods of time, like during the winter in the colder parts of the globe, and then fire their cars up with no issues? Maybe I'll consult my local tarot card reader...

Partial Post: Please Login or Register to read the full post.

[flash]

lol - there we go again. just because somebody has never had a problem...................

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

[quote name='flash' timestamp='1347302396' post='132483']

lol - there we go again. just because somebody has never had a problem...................

[/quote]

I hear you, but this is a little more than "somebody". Millions of cars sit for extended periods, and have no issues with their belts. I can understand sitting for years, through temperature extremes. If replacing it were a fairly simple job, I would probably do it, as the belt is quite cheap, but on a 968, it's a multi-hour task. Haven't made up my mind on this one. Any other inputs out there?

Partial Post: Please Login or Register to read the full post.

[tamathumper]

My advice would depend on my previous question - is the tensioner fully "pumped" when the engine is just sitting like that? If not, then the belt isn't under much tension and I'd be less inclined to replace it.

Partial Post: Please Login or Register to read the full post.

[flash]

i'm a lot more cautious on this one. given that the only thing preventing catastrophic failure is the timing belt, i would not mess around there. if there were any question about the belt taking a set, i would change it. the balance belt and accessory belts i would not be nearly as worried about

Partial Post: Please Login or Register to read the full post.

[ds968]

For me it's a tough call because I felt the sting of a failure and definitely don't want to risk repeating the experience. Now, in all fairness, this happened at just a few thousand miles before the Porsche prescribed 60 k mile interval, but the belt also had more than six years in the car. Compounding the age and mileage problems was a huge temperature swing ( 105 to 40 back to 100 + again ) in a period of two days, and then my usual driving habit of frequently bringing it to 6500 - 7000 rpm . So I would imagine it's the combination of all of those factors coming together in a "perfect storm " caused the catastrophe and I doubt any single one of those by themselves, whether the six years, or 55k + mileage, or the consistent 6k rpm + habit, and without the temperature shock would have resulted in the same outcome. BTW, my balance belt , of same age an mileage looked and felt ( on twisting, flexing, cracks inspection, etc ) as if it was "out of the box " new. Very odd, since I near those go first ad take out the timing belt with it. Anyway, I get the impression that if driven only 2 k miles a year ( which is what I

average nowadays ) any belt can probably last at least 10 , maybe even 15 years. but I'm sure as hell not going to bet $ 6,000 on that theory and will probably change them after four years, even if they have

lesss than 10k miles on them at the time. My mechanic thinks I'm insane for doing that, but he'll gladly

take my money to do the job, if I insist, LOL . It's called insurance.

Partial Post: Please Login or Register to read the full post.

[KRAG50]

Yes the tensioner is fully pumped with the engine off, the tensioner is pressurized internaly, not thru engine input.

Partial Post: Please Login or Register to read the full post.

[MB968]

Wish we knew exactly why the belts were failing. From my experience, its an odd phenomina. When I was working, if we'd had this type of pattern of failures, we would have sent the belts back to Gates, or Dayco (our two major suppliers) for their engineers to do a failure analysis. I used to have contacts in their labs. If we could gather up a few failed belts, I'd be willing to pursue this with Gates to see what their engineers could tell us. It may not change our PM schedule, but might shed some light on what to look for.



And, since I now know how easy it is to do a visual inspection (just a few bolts gets the top cover removed) I plan to at least do an annual (or sooner) inspection to look at the belts while running (everything should run smooth with no significant vibration). And to do a better visual/tension check while stopped.

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

[quote name='KRAG50' timestamp='1347378101' post='132534']

Yes the tensioner is fully pumped with the engine off, the tensioner is pressurized internaly, not thru engine input.

[/quote]

Yes, that's right. If it were you, would you replace the timing belt before firing it up? It's a "new" belt, in that it has never been run, but it's had been sitting motionless, under full tension, from late April to last night (finally rotated the engine by hand last night). My gut feeling is that replacing an unused belt after such a relatively short period under fairly constant temperature, is gross overkill, but on the other hand the risk is tremendous, as I have a new set of $1000 pistons, which, along with the valve faces, I've had ceramic coated).

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

MB - Good points as always. Yes, it would be great to know the failure mode. Anecdotally, I get the impression that the balance shaft belts fail at least as frequently as timing belts, which I'm not worried about letting sit, because it's under such relatively light tension. Even the timing belt isn't that tight, compared to the alternator/AC belt.

Partial Post: Please Login or Register to read the full post.

[MB968]

How many people have lost a timing belt without loosing a bal belt?

Partial Post: Please Login or Register to read the full post.

[ds968]

[quote name='MB968' timestamp='1347385148' post='132544']

How many people have lost a timing belt without loosing a bal belt?

[/quote]





well, me of course.. as I noted above, the balance belt was not only in perfect shape, but it was still in its proper place and did not "skip a beat" ( or tooth ) or tension difference, or anything else in the process of the timing belt being shred to bits.. !

Partial Post: Please Login or Register to read the full post.