Engine belt change interval

[Junk Parts]

I use Gates belts and have had no problem with them squealing ever. I do tend to trust Gates products. With timing belts Gates is the only brand I'll use. Now in all fairness the OEM product has something going for it too. The Honda belts are perfectly alright but sort of costly. Why pay for just the word "Honda" printed on the belt when Gates offers a product that is just as good? I did buy a Pirelli belt one time but didn't use it. It had a bump in its kevlar backing. There is no way in hell that you would ever want a timing belt with a bump on it.

[dmill89]

Originally Posted by stevo1210

Okay, I can see cracks in my belt... though small but they are there... I do drive harshly sometimes (when I'm in a rush to work or late to a function), so I don't want this thing to snap anytime soon; especially on the way to work. :-/
Anyway, should I get a factory belt (Japanese made Denso belt) or an aftermarket belt? I've been told aftermarket quality is supposedly better but they tend to squeal after a while? My 10 year old belt doesn't squeal... ever.

To second what JP said aftermarket belts are fine as long as you stick with good brands such as Gates, Denso,Bando,etc. Avoid off brands and anything made in china at all costs.

[larrymoencurly]

Originally Posted by stevo1210

Anyway, should I get a factory belt (Japanese made Denso belt) or an aftermarket belt? I've been told aftermarket quality is supposedly better but they tend to squeal after a while? My 10 year old belt doesn't squeal... ever.

I think aftermarket belts are made by the same companies that supply the auto manufacturers, and I've been buying the cheapest stuff, which has usually been Kelly-Springfield brand at AutoZone. They're the same as Goodyear but don't have a lifetime warranty. Some manufacturers produce 3 quality grades of belts -- regular, toothed inside, and toothed both inside and outside. The teeth don't grip but only make the belt run cooler by letting it flex more easily; it's the sides of the belt that do all the gripping. Only the first few belts I installed squealed, so now I check the tension after 15 minutes of operation and then again after the belt is stone cold (rubber expands when it cools).

[mathog]

Originally Posted by larrymoencurly

Some manufacturers produce 3 quality grades of belts -- regular, toothed inside, and toothed both inside and outside. The teeth don't grip but only make the belt run cooler by letting it flex more easily; it's the sides of the belt that do all the gripping.

I think you mean the teeth don't engage rather than the teeth don't grip. The rubber on the bottom (or top, depending how you look at it) of the teeth does grip the pulley, but there are no corresponding pulley "teeth" to engage the teeth on the belt.

Originally Posted by larrymoencurly

Only the first few belts I installed squealed, so now I check the tension after 15 minutes of operation and then again after the belt is stone cold (rubber expands when it cools).

No, it shrinks when it cools. Very (very, very...) few materials have a negative thermal expansion coefficient, although water does over some temperature ranges in both its solid and liquid forms.

[larrymoencurly]

Originally Posted by mathog

I think you mean the teeth don't engage rather than the teeth don't grip. The rubber on the bottom (or top, depending how you look at it) of the teeth does grip the pulley, but there are no corresponding pulley "teeth" to engage the teeth on the belt.

You're right.

Originally Posted by larrymoencurly

rubber expands when it cools.

Originally Posted by mathog

No, it shrinks when it cools. Very (very, very...) few materials have a negative thermal expansion coefficient, although water does over some temperature ranges in both its solid and liquid forms.

The molecules of at least some types of rubber curl up when they're cold, including the rubber for car belts and latex rubber:

http://www.physlink.com/education/askexperts/ae478.cfm

Here's a wheel made of rubber band spokes that spins because heat applied to one side makes spokes on that side contract.

http://www.youtube.com/watch?feature...&v=0igUqDg7f98

However another YouTube video where a bicycle wheel is used says the heated rubber expands, but I don't think that's right because I remember a science fair project where the rubber bands were attached to a crankshaft (bent needle or wire), and the heated side pulled the crank:

http://books.google.com/books?id=mzW...page&q&f=false

[mathog]

Originally Posted by larrymoencurly

The molecules of at least some types of rubber curl up when they're cold, including the rubber for car belts and latex rubber:

http://www.physlink.com/education/askexperts/ae478.cfm

Here's a wheel made of rubber band spokes that spins because heat applied to one side makes spokes on that side contract.

Interesting, there are two thermal expansion terms. When heat is added to bulk rubber (not stretched) or most other materials the entropy goes up because the molecules shake more, everything tends to space out a bit, and the thermal expansion term is positive. Rubber molecules when not stretched are balled up. Stretch them and they elongate. Adding heat to that offers another way to increase entropy - by folding back part way into a ball, ie contracting. The term that will dominate will depend upon the amount the molecules are stretched. In a rubber band a stretch of 2 or 3X is common and the folding term can dominate. In an installed drive belt though the stretch is, what, <1%? My gut feeling is that since there isn't much stretch to start with the normal thermal expansion term will dominate, but I cannot give numbers to prove it.

Could be a fun little physic experiment here. Drive a nail through a ruler and hang a rubber band on it. Hang various size weights on it, enough to expand it various amounts, say from 0 to 3X. Measure the displacement. Warm it up with a hair dryer and measure the new displacement. How big does the initial displacement have to be for heating to result in contraction?

[PWB]

I just replaced my serpentine belt on my 2004 Dodge Dakota. It looked good. It had 162,000 miles.

PWB