what is the difference with a timing belt and timing chain?

Question

can you adjust a timing chain on an 2000 altima. if your timing is off and you have a chain how do you fix it. if you get it fixed, is it likely to go off again.my mechanic messed with the distributor cap and said he adjusted it. does this sound right? spark plugs had some oil like substance on the white part of them.is that bad? i just bought this car two weeks ago. it ran great then now it sounds like an old piece of junk . someone please help.

well i would like to add some of the problems that im having, it is making a muffled air sound and is running very rough.i have to give it gas so it doesnt die out.when on the highway the rpms jump up and down and it feels like a loss of power.or a little jerk.and at stop sign it dies.the check engine light has not came on.

Answer 1

The deal is, sporto, timing belts and timing chains do exactly the same thing. The difference is what they are made of. Timing chains are metal, and they look like a bicycle chain only wider and much heavier-duty. Timing belts are reinforced rubber, and look like serpentine belts, but they have "teeth". "Cogs", if you will. Both a chain and a belt connect the crankshaft to the camshaft(s) so that the intake and exhaust valves are always synchronized with the pistons. You cannot adjust timing belts or chains other than getting them installed exactly right in the first place. There is a tensioner that takes up any slack and keeps the belt or the chain tight so it doesn't rattle or vibrate or come off the sprockets. If the camshaft(s) and the crankshaft are not aligned properly, your engine will do one of three things: Not run at all, run very poorly, or in extreme cases damage itself when the valves hit the pistons. Over time, timing belts and timing chains stretch and wear out. In either case, they need to be replaced. Timing chains are generaly replaced as a matched set that includes the chain and the sprockets it rides on, because the teeth in the sprockets can wear out or sheer off. Both chains and belts can break. Timing chains are much less likely to break, but it does happen. Most of the time they stretch, which causes sloppy valve timing, and since the distributor is driven by the camshaft, it also causes sloppy ignition timing. I believe your Altima has a timing chain. Usually, timing chains don't just jump teeth or get out of adjustment. They simply wear out, stretch, and sometimes break. Your car is almost 7 years old. Under the hood is a dirty place. A little oil on the plugs is probably no big deal. Replace them and see what happens. Adjusting the distributor cap should have exactly no effect on the way the car runs since it's not adjustable. Replacing the distributor cap can make a world of difference, because often times, distributors get what is called carbon tracking, which causes the spark plugs to fire wrong or not at all. Here's what you should do: Fix the cheap stuff first. Get yourself a set of plugs, a set of wires, and a new distributor cap. Put them in. Get a new air filter. Put it in. If your problems don't go away, see about getting the ignition timing checked. That's one way a mechanic can find out if your timing chain is the problem. Late model cars like yours often don't have adjustable ignition timing, because it's all computer controlled. But if the timing chain is stretched beyond what the engine's computer can correct for, it needs to be replaced. That means pulling off the front cover of the motor, taking off the sprockets and the chain, as well as many other parts that are in the way, installing the new timing set, making sure it's set correctly, and putting all that stuff back together. It's not an easy job, and when my car needed it, it was almost 400 bucks. FYI, I'll bet you that your timing chain is fine unless you have a buttload of miles on your car. I've had lots of cars, but only one broke a timing set, and that was at 250,000 miles, and that's because Ford used plastic teeth on the sprockets.

Answer 2

You've asked a lot of questions and may be confused about a couple of things. First, a timing belt is made of rubber and has rubber teeth... really! A timing chain is made of metal and looks much like a bicycle chain. An engine with a timing belt has sprockets that look a lot like gears, around which the timing belt is fitted. An engine with a timing chain has sprockets much like what you see on a bicycle.

Both a timing belt and a timing chain can be incorrectly installed, which can cause a variety of symptoms on a car. Since a timing belt has more teeth, it is easier to get it mis-installed by a tooth in either direction. In some cases, this could give the car more power under certain conditions. However, it's always best to install the belt/chain exactly as the manufacturer recommends. Timing belts/chains take power from the engine's crankshaft and deliver it to the engine's camshaft. Since the camshaft operates the engine's valves, the "timing" that the timing belt/chain does is valve timing. (In some cars, the distributor operates off of the camshaft, so the timing belt/chain can affect the distributor.)

When your mechanic adjusted your distributor, he was adjusting the ignition timing, not the valve timing. Getting the ignition timing right is a good thing, so your mechanic was probably helping things by adjusting it.

I don't know how much oil was on your spark plugs but an oil smear on the outside of a spark plug is nothing to worry about. Most engines have a bit of oil leakage here or there, and a little oil can get splattered around. If you unscrew the spark plug and there is oil on the electrode, then your engine is leaking oil internally and it is fouling the spark plugs. This is an expensive repair, usually a valve job but sometimes an engine rebuild.

From what you've explained, it's hard to say why your engine is running poorly. Please give more of its symptoms and I may be able to give better advice.

Answer 3

It sounds more like a vacuum leak than a timing issue. There are ways to check for such that are not real expensive. Spray a can of starting fluid (that is ether, careful it is flammable) into the area that the air sound is coming from while the engine is idling. If the idle smooths out while applying the starting fluid, it is a vac leak. The computer will attempt to mask a vac leak via adjusting the fuel mix up to a point. I had a VW Jetta gas engine that the rubber boot between the oil fill cap and the rocker cover was leaking vacuum, causing rough idle issues and slightly lower fuel mileage. I replaced the spark plugs, the plug wires and tried adjusting the timing. When I located the bad rubber boot and replaced it, the fuel mileage went up and the problem went away.

Some cars have non-adjustable timing, but they also tend to not have a distributor. They use a "distributorless" ignition system, coil packs that fire directly at each cylinder or multiple cylinders (as did my Chrysler Concord in 1993) that are also computer controlled.

You have adequate descriptions of timing belt vs chain. A short recap: timing chains are internal, timing belt external. Timing belts require changing more often than timing chains, neither are not cheap to replace, both serve the same function.

Answer 4

Older cars have a timing chain. It was just that, a metal chain that drove the timing mechanism of the motor. Almost all cars since the late 1980's use timing belts, much like the fan belts in the motors of cars, or the serpentine belt in a newer car.
Both the belt and the chain have one thing in common; if they break, the motor will not run. If you have a timing chain, it can slip on a tooth or two of the pulley that turns it. When that happens, you will lose power and performance. A mechanic will have to go in and fix it, or more often, replace it. The same can be true of a timing belt; you probably should just have the timing belt replaced if the car has over 60,000 miles and has not had the timing belt replaced. Most car manufacturers recommend this.
BUT- Your description of the problem does not sound like a timing belt problem; it could be something in your exhaust system. Have another, more trustworthy mechanic look at your exhaust system. A leaky muffler or tailpipe can sound awful. If the car is still running great, but just sounds bad, I would look at the exhaust system first.

Answer 5

mrfinger86's answer is not fully correct: the belt is technically outside of the engine, but both timing belts and chains are found underneath the valve covers of an engine--NOT VISIBLE unless the valve cover is removed. Timing chains are just that--chains. They don't typically need to be replaced, but sometimes they do stretch/ warp, and that will cause an engine to run poorly and possibly critically unsafe. They are more expensive to replace in both parts and labor--it is more difficult to change a chain than a belt, and the part itself is also more expensive. Belts WILL break over time. Usually not before 120000 miles, but it depends on the belt and use. Most service manuals for modern cars recommend changing them anywhere from 60K to 100K miles. DON'T LET IT BREAK! An ounce of prevention is a pound of cure, seriously. Some engines can be VERY seriously damaged if the timing belt breaks. So replace it according to the service interval foudn int he owner's manual, and you should be OK. Replacing a timing belt/chain is not a DIY job, unless you have substantial experience with engines already, and the proper tools...

Answer 6

A timing belt is like a fan belt made out of rubber. A timing chain is just that. A metal chain. Both do the same things. Both can stretch and both can break. You can adjust a timing chain/belt on any vehicle but if it is old and stretched out, it won't do much good and the timing will be off again. It's expensive to fix.

I'd get the thing running again if possible and sell it before something else goes wrong. Sorry you're having such bad luck.

Answer 7

The timing belt use over chains and gears is another way for them to present more problems that the average motoring public have to put up for repair. They should be changed every 60'000 miles or less and if not there is a chance of further damage than a 30--100 dollar belt replacement, so go, go buy new car.

Answer 8

Timing chains are internal to the engine, while timing belts are external.

It sounds like you need to see another mechanic.

Answer 9

Timing belts need to be replaced every 60,000-90,000 miles and Timing Chains are not replaceable there should never be anything wrong with them. They also have a lifetime warranty on it from nissan. Hope that helps