Some of the most important parts under the hood are made of rubber, the belts and the hoses. Now, because they’re made of rubber and other things, they do have a finite life and they do need to be replaced on a regular basis. That regular basis is every four years or 60,000 miles. And, in the meantime, you should be checking them regularly, at least once a year.

Now before you can really determine anything about a belt, you have to understand how they’re made up. They’re made of layers. See here we have one that we’ve taken apart. We have an outer layer. Then underneath that we have an actual belt-like substance, just like the belt around the outside of a tire. It forms part of our drive belt. And this fabric, over a period of time, breaks down. It loses its strength. And when it does, the belt can fail at any time.

Now here’s where the problem comes in. You can’t see that reinforcing material. What you can do is you can look at the belt. If it’s obviously all torn up like this one, no question. This belt is bad. Anybody could see that. But maybe it isn’t quite that far gone. Well, if we bend it backwards a little bit, we see a whole bunch of cracks in it.

But now, here’s the dilemma. If your belt looks perfect, then it might be fine. But if it’s been on the car four years or 60,000 miles, it needs to be replaced because we can’t see the reinforcing fabric inside, and it could be shot. Oh, by the way, belt dressing, okay on the old-fashioned V belts, but don’t use it on newer serpentine belts because it can make a mess like you’ve never seen.

All right, hoses. Hoses are made up the same way. They have layers, again, have fabric and rubber. The only thing you can see is the rubber on the outside. The fabric is what goes bad. The fabric fails, the hose explodes, and you have an overheated car, and it can do a lot of damage.

Now if you were to look at this hose, up here it looks pretty good. But we get down to the other end of it and we see that the fabric has completely deteriorated, and this hose literally exploded and all of the coolant came out of the car. Four years, 60,000 miles, that’s when you replace belts and hoses, unless they fail before that.

Now, one other thing. Lots of people like to have everything looking great under the hood of the car, and one way to do that, spray things with silicone. It makes hoses look wonderful. It makes all the black paint look wonderful. Don’t do it! The silicone in the container will go through the air filter, out through the exhaust on the car, contaminate the oxygen sensors, and you buy new sensors, many times quite expensive.