My new timing belt dosen't look so new anymore.

[Tegger]

Originally Posted By: Kestas

The belt manufacturers specifically state the number one reason for belt failure is not the belt itself, but rotating component failure (tensioner, idler), resulting in a shredded belt.

Yes, it's always best to change those parts. Plus, you're all the way in there anyway, so most of the labor is shared. I've found that Honda OE tensioners usually go two belt-changes before they get loose enough to make noise. Honda OE water pumps go maybe a change-and-a-half to two changes before they start to get loose. This is assuming the changes are being done according to the manual, and that the coolant is OE and is also changed according to the manual...

 

[Cardenio327]

Originally Posted By: vtecboy

with a timing light you can see the timing mark jump around when you rev up the engine,just as the timing chains.

The timing mark is jumping around because the computer is constantly adjusting the timing ° according to rpm, load, &c. When you rev the motor up it is going to adjust the timing all over the place. If you hold it at a steady speed it will settle into whatever ° advance is appropriate for the rpm and load.

 

[vtecboy]

http://www.youtube.com/watch?v=3zyjyVUoe6c someone asked scottykilmer in the comments section of that video if timing belt stretchs like chains and he said: "na, they stretch like mad and make the car run weird when the do in some models" but it looks like no one here agrees with him. lol

 

[yonyon]

Most don't stretch much but some do. I've replaced quite a few on Toyota MZs not for PM, but because the owner found the noise from the very old stretched timing belt to be annoying.

 

[Tegger]

Originally Posted By: vtecboy

http://www.youtube.com/watch?v=3zyjyVUoe6c someone asked scottykilmer in the comments section of that video if timing belt stretchs like chains and he said: "na, they stretch like mad and make the car run weird when the do in some models" but it looks like no one here agrees with him. lol

Kilmer may be right for some models, I don't know. But I think he's flat wrong, unless those "some models" are really badly designed. But the OP has a Honda, and the belts used on Hondas are NOT supposed to -- and do not -- stretch even a little bit. Our family also has a Tercel, and that belt doesn't stretch either. I know this because the slack on the belts I've done does not change from installation to replacement. Toothed rubber belts are/were used for a long time on engines specifically because chains DO wear and stretch. In this age of emissions compliance, chain-stretch means valve/ignition timing that slowly goes out of spec, increasing emissions. Since belts do not stretch, that's one source of increased emissions eliminated. It's true that automakers are slowly moving back to chains for reasons of reducing maintenance requirements, but engine controls are now sophisticated enough that they can compensate for wear and stretch. The toothed, fabric-carcass belt used for timing engines is NOT supposed to stretch. The exact same type of belt (made by the same suppliers!) is universally used on the computer-controlled X-Y plotters used in my industry, where precision is a life-and-death matter. If the belts stretched, we'd all be out of business. Those belts BREAK, especially if overtightened, just like automotive belts. Personally, I believe Kilmer is talking out of his hat.

 

[Tegger]

Originally Posted By: yonyon

the owner found the noise from the very old stretched timing belt to be annoying.

I'll bet the noise was the tensioner. They get rattly when they wear too much. Belts are quiet even when they're too loose. That's one reason some automakers went to them before the days of emissions. You even used to be able to buy kits to convert certain chain/gear engines (BMC A-series engines, for instance) to belts to get rid of the noise from the chains or gears.

 

[zzyzzx]

That timing belt pictured looks fine. Would be nice to see what the old one looked like.

 

[yonyon]

Originally Posted By: Tegger

Originally Posted By: yonyon

the owner found the noise from the very old stretched timing belt to be annoying.

I'll bet the noise was the tensioner. They get rattly when they wear too much. Belts are quiet even when they're too loose. That's one reason some automakers went to them before the days of emissions. You even used to be able to buy kits to convert certain chain/gear engines (BMC A-series engines, for instance) to belts to get rid of the noise from the chains or gears.

No, it wasn't worn tensioners. It's just a matter of so much slack that the belts are flapping around. They can get that loose - as in "Why didn't that thing jump time?" loose.

 

[Tegger]

Originally Posted By: yonyon

No, it wasn't worn tensioners. It's just a matter of so much slack that the belts are flapping around. They can get that loose - as in "Why didn't that thing jump time?" loose.

I find it impossible to believe that the belt "stretched" to that degree. I have 20-years of experience with toothed belts in various applications, and not one has ever "stretched". If your friend's belt was slapping around that much, then it was incorrectly installed, or some other part was severely worn.