I own a 2007 S2000 with 19,800 miles, 100% stock. I'm the second owner and I'm fairly certain that none of the engine belts have ever been changed. I replaced all fluids in the car last year. The car runs flawlessly and the engine looks like it just came off the showroom floor, including the belts that I can see. Looking for guidance on whether I should have the belts replaced. Thanks is advance for recommendations.

 

There is a belt stretch indicator on the engine, but I don't think it is very reliable, as new belts still show up as overly worn.

If it was my car I'd change them now, if tires have a 10 year life span I would use the same estimate for belts, just my opinion, the miles are low but the belts are aged in terms of time. They are cheap and easy to swap.

 

I bought my 01 at 103,000 miles in 2014. It had the same part number as the OEM belt on it then. no clue if it had been replaced but if it had it was not recent. I replaced it at 146,000 miles in 2019. It still did not appear overly stretched and looked good (no cracking). I replaced it because I was doing the idler and tensioner bearings and figured I may as well at that point given its age. I am at 165,000 miles now and it is still looking great. But as mentioned they are cheap and super easy/quick to change so does not hurt to know you have a good fresh one on it given its age.

 

I'm certain you don't need to replace it.
But If you still want to, only use an oem Honda belt.

Your aged original belt will still outlast a brand new aftermarket belt.

I replaced my belt even though it was still ok, just in case. It had 150k miles, and was over 15 years old. Still not stretched beyond spec, still not dry rotted. A few minor age cracks.

 

modern belts wear the tooth pattern down, they do not show cracking, rapid discoloration, or stretch like what we used to look for. we now use wear indication tools to get a better idea if we need to suggest a new belt.

 

Belts, like chains, don't actually stretch. They both do however, get longer while in installed position.

For a belt, the wear shown in pic means that it hugs each pulley a bit closer. Added up around each pulley, that means there is more slack for tensioner to take up.

Since tensioner is a spring, whose pressure is measured in distance by force, the more its unwound, the less tension it has. So even as belt has less surface contact to pulleys, it also has less tension. So once it gets well worn, it can slip.

Hence the value of wear guide on tensioners. Ours hapens to be a bit off. As a brand new oem belt will be surprisingly close to replacement mark on tensioner.

A belt wear guide as shown is better than tensioner wear guide. But tensioner wear guide is still valuable.

 

I picked up my 2004 with 20,698 miles on it this last year, and while I was going through everything I just replaced the belt due to the age. Probably could have ran it fine for years but I was getting fluid and a filter from Honda so I just got the belt as well.

 

I would replace it and keep the original belt in the trunk as a spare.

 

I actually thought about doing this as well. Good idea.

 

What's the oem part-number for the Ap1 belt? (last owner installed an aftermarket 3rd-party belt)

This is actually the only maintenance item I have not got around doing yet (of course, did all the fluids, valve adj, tct, full genuine clutch, etc. already).