I ran a belt for 7 years and when it came off there was no signs of degradation.
That was a HTD belt, so it could be different, but I would be inspecting all the other parts closely.

 

I'm not convinced age matters that much. The belts, at least the Gates and Porsche ones, are Kevlar reinforced and just don't stretch or get brittle or much of anything if the belt track is in good working order. Still, I always examine the belt every year or 15K miles. I've pulled off 10+ year old belts (one was over 20) that looked brand new. You could still read the lettering on the backside, they were not glazed or micro-cracked at all, not frayed, and the tooth surfaces looked like new. But when there are issues with the belt track, even nearly new belts will show damage. I saw one belt, not very old, that appeared to have been "creased" in a couple of places and one of the creases broke. That was nasty and apparently from improper handling (folding) of the belt before it was installed.

 

I'm with Bill. Someone needs to look closely why it failed. I doubt it was the tensioner or belt age that was the major contributor.

 

I'd like to see some photos of the remains of the belt.

d[O2]/dt = - ρ(T) * ([O2]/(1+a[O2]))

This is the formula for rubber oxidation. For constant conditions, the oxidation rate of rubber is relatively constant with time. This formula scheme outlines the relationship between oxygen consumption, oxygen concentration, and temperature.

After looking up some studies on rubber oxidation, I found statistics that very few tires make it past 7 years even with low mileage on them. Depending on the formula of the specific rubber of any given product, the oxidation rate can change slightly, but it is still always present. While most of the studies I found reference tire and other automotive technology, the fact remains that rubber parts will always deteriorate as long as they are exposed to oxygen, and faster still if exposed to heat.

Ever seen a rubber band that's been in a drawer for 6 months? No sunlight on it, but when you stretch it it is rotted and snaps?

While I fully agree that the entire rotating assembly needs through investigation and could have caused the break, anyone tempting fate by running a belt for more than 7 years (I'd never go past 5 in an interference motor) is ASKING for a broken belt. I don't care if the belt is lined with Kevlar or unobtainium, the rubber will be highly oxidized and will lose what is known as it's CGR (crack growth resistance). Time kills rubber period. Belts, fuel lines, and hoses can look great and still be highly oxidized, and I think it's irresponsible to tell anyone that a 10+ year old belt can still be ok to run because it "looks new".

My two cents. Take it for what it's worth.

 

Rubber oxidation/deterioration is climate/environmetally affected (?ozone). I would think that would show as microcracks and other signs of derioration. There's a lot more to these belts than rubber. I've seen badly oxidized tires that develop cracks and fail to hold air, and that can happen in a relatively small number of years. I still have not seen a 928 timing belt look like that. If his belt has cracks all over and looks like crap or the Kevlar loses its integrity, then so be it, age is more of an issue than I thought. Porsche didn't set and age spec for the belt as far as I can determine. I don't mean to imply that therefore they last forever, but they seem to be very durable.

 

All new fuel lines last year... I will report back after Mechanic informs me of any other reason for failing....

Thanks.........Rick

 

Rick! That just sucks.

Me three.

100% agreement.

Unless the belt was dry-rotting - not going to happen in Rick's ultra-man-cave-garage - something else was the primary cause and the belt did all it could in the face of the primary failure until it became collateral damage.

 

6 years or 60,000 miles IIRC and legend (Rennlist) has it that a TSB extended to 10 years or 60,000 miles. (I didn't care about the 10 years part so I never confirmed this legendary TSB.)

Nevertheless, I agree with you, There is a lot more to the belt than rubber.

I have not seen a "bad belt" yet. I have seen belts chewed, missing teeth, or a bit shredded and always, always, always the condition of the belt was an effect not a cause.

But, I won't let a belt go more than 7 years.

I have seen pictures of a bad belt.

 

Who is the guy, where in Merideth. That is half hour from me.

 

in the OP.... unbreakable belt? where do you get that? First thing that comes to mind is Titanic.

 

Hey Gretch, Its Paul at Auto Haus, 335 Daniel Webster Hwy. very close to the intersection of 3 and 25 near the "Inn at Mills Falls" looks like at one time it was a Citgo station. No word yet from him....... I wish I was closer, its a two and a half hour ride from my home... I'd be thrilled if you could stop by there.

Thanks, Rick

 

Good luck Rick.

 

Rick, hope it is back on the road soon and without much wallet damage.

 

Bill,

I'm not sure about your statement about the Porsche and Gates (standard Gates) belts being reinforced with Kevlar.

Most all the coolant hoses in our cars ARE reinforced with Kevlar (It is a yellow fiber cord with lots of fine filaments that make it up - filaments are much smaller than a human hair). All of the belts I've seen that have been cut (or broken) are reinforced with fiberglass (you and I are old enough to remember fiberglass belted tires from the '60's and know how they performed!).

I worked in the development of Kevlar for rubber reinforcement in the early/mid '70's, as I was an employee of the company that invented and produces it. GREAT product, but many times more expensive than fiberglass, so was slow to be adopted in many automotive applications (cost is a real issue for OE automobile adoptions - especially when the component is hidden by rubber!!). Coolant hoses used to fail frequently as they were reinforced with rayon or a synthetic that is affected by heat/humidity. Kevlar has nearly no stretch and is 5X stronger than steel per lb.

It's tensile strength is hardly affected by temperatures up into the 400-500 degree F range, so it is great for coolant hoses and is/would be great for timing belts as well. It is of course the reinforcement in the new Gates "racing" timing belt for 928's. That belt's price is about 5X the standard belt, as I recall).

Gary--

 

Gary:

Actually, I think you're right - the "standard" Gates timing belts are Aramid-reinforced, now that you bring this up. That's a pretty indestructible, high tensile strength, heat-tolerant polymer as well, used like Kevlar in ballistic protection, etc. Kevlar is a "para aramid", a derivative with a few positional changes to the molecule. It may be that all the Gates belts are Aramid-reinforced. Roger may know from his dealings with Gates on the racing belt.