Old belt was sqeeking, new belt does not but it slips off constantley. The old belt stays on though. Why is this?

My old drive belt was sqeeking so i replaced it. The new belt does not squeak but it keeps slipping off. But when I put the old one back on it does not slide off. Why is this? I replaced tensioner and idler pulleys but new belt still slips off. The old one still stays on. Car is 97 jeep grand cherokee. 5.2L
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
Check to be sure that the new belt is actually the right part number or, better yet, use an OEM (dealer) belt. Also, be sure the tensioner is the right part number or use an OEM sourced tensioner. Check to be sure that all of the pulleys and accessories (e.g., alternator, water pump, A/C compressor) that are driven by the serpentine belt are all operating in the same plane. It is not unusual for the pulley on the crankshaft harmonic balancer pulley to move (generally outward) relative to its original position. The pulley is rubber bonded and over time can move. If that pulley moves, that means that the belt groves are no longer running in a perfect plane and that alone can cause slipping. If you request serpentine belt inspection a certified Mechanic, dispatched by YourMechanic right to your location, will identify the problem and thence get the issue resolved for you promptly. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

How to Identify and Fix Common car Problems ?

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Serpentine belts are much longer and wider than older V belts. Improved material quality lets belts last much longer. A narrow, deep V-belt design evolved into a wide, flat belt with teeth. Several V belts on older engines have been combined into one serpentine belt on newer engines.
The belt squeals because there is improper tension in the belt drive system. This is usually caused by a worn automatic tensioner, but other causes can include a contaminated belt (oil, belt dressing, etc.) or a belt that is too long or worn out.
Made of sturdy rubber, this part may last anywhere between 50,000 and 100,000 miles.
Is a serpentine belt the same as a drive belt? The fact is that the two are often used interchangeably and are easily mistaken for each other. But they are actually separate belts.
The advantage of a serpentine belt is its efficiency. Having a single belt increases fuel economy and available power. The disadvantage of a serpentine belt is if it breaks several critical functions of the engine are lost and the engine will conk out leaving you stranded.
If your serpentine belt is failing, you may notice performance issues with your vehicle. The vehicle may frequently overheat. Your air conditioning or power steering may fail to work or not work properly. You may notice your vehicle battery failing to recharge if the alternator is affected by a bad serpentine belt.
As these belts wear out, they can begin to squeak or squeal. They make noise because there is not enough tension on the belt, or because the pulleys are misaligned or weak. Often, simply changing the belt will make it stop squealing. The noise isn`t usually a danger, though it does sound alarming.
It`s a reinforced, ribbed rubber belt that delivers power to your alternator, air conditioning, power steering, cooling system, and other components in your vehicle. Usually, these belts don`t require maintenance, and will last up to 150,000 miles.
Loosing the serpentine belt should not affect the engine timing.
The thicker multi-rib design of the serpentine belt provides a better belt to pulley contact ratio that creates less slippage. With most serpentine systems only using one belt there will be less distance between the accessories, simplifying the engine compartment. They use proper tension with the help of the tensioner.
A serpentine belt is one long rubber belt along your car`s engine that provides power to many vital components in your car like the alternator, power steering pump, air conditioning and sometimes the water pump, according to Firestone.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Old belt was sqeeking, new belt does not but it slips off constantley. The old belt stays on though. Why is this?
ANSWER : Check to be sure that the new belt is actually the right part number or, better yet, use an OEM (dealer) belt. Also, be sure the tensioner is the right part number or use an OEM sourced tensioner. Check to be sure that all of the pulleys and accessories (e.g., alternator, water pump, A/C compressor) that are driven by the serpentine belt are all operating in the same plane. It is not unusual for the pulley on the crankshaft harmonic balancer pulley to move (generally outward) relative to its original position. The pulley is rubber bonded and over time can move. If that pulley moves, that means that the belt groves are no longer running in a perfect plane and that alone can cause slipping. If you request serpentine belt inspection a certified Mechanic, dispatched by YourMechanic right to your location, will identify the problem and thence get the issue resolved for you promptly. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Timing belt is tight and yet appears to be slipping several teeth when belt is rotated,
ANSWER : This is okay since there are more notches on the belt than the amount on the sprockets. Once you aligned the first time the belt marks will almost never line up perfectly again. The marks are used to put the belt on correctly. They aren’t used as an indicator after the engine is turned again. You should be okay to start the motor as long as timing marks on pulleys line up. If you run into any issues, have a certified technician, like one from YourMechanic, assist you with the replacement of the timing belt.

hey i had a belt break while traveling on my 2004 honda pilot. It is the small belt and not the serpentine belt. The mechanic t
ANSWER : Hello. The smaller belt is known as your timing belt, and it works inside the engine to keep mechanical components aligned with each other during the compression cycle. The serpentine belt, which is the big belt, drives the alternator, water pump, AC compressor, and a couple of other components. If the small belt broke it is likely the timing belt. This will cause the car to stall, lights to illuminate, and can even cause serious damage to the engine. Typically replacing a timing belt is a lot more complicated and expensive than replacing a serpentine belt. You may want to receive a second opinion on the car before you go ahead with repairs.

changing timing belt on 10 year old car with 52k miles, not required till 102 k but decade old belt= bad?
ANSWER : My suggestion would be to take a close look at the belt for microscopic cracks or signs of deterioration. If anything is noted, I would spend the money and replace it as this is a relatively cheap "insurance policy" against the possibility of failure resulting in thousands of dollars of potential damage should it fail. As you know, with this generation of interference engines, a broken belt can cause a nightmare of damage. If you would like to replace your timing belt, a certified technician from YourMechanic can come to your home or office to perform this service.

Can you change the defected water pump without changing its defected belt (which is the drive belt and only belt in this model of
ANSWER : Hello. Yes you can replace the water pump without replacing the serpentine belt. If the belt is worn, and it breaks while you are driving, you can damage a lot of other components in that area. Typically the price of a serpentine belt is relatively inexpensive. You will have to remove the belt to replace the water pump anyway. Since you are likely going to have to purchase a new pump, we do recommend that you purchase a belt at the same time. You SHOULD replace the belt if it is worn, and this is a perfect time to do it. It is not necessarily required, but you are putting yourself at risk of another break down at a later time. Not to mention if the belt is already worn, manipulating off and back onto the vehicle while changing the water pump can further damage it, and shorten the amount of time its got left. Belts should be replaced before they break, as to the amount of damage they can cause when they do break. Again, you may be able to get away with not replacing the belt right now, but if its as worn as you say, its going to break sooner than later and should be replaced.

We have a new battery, new alternator, new coil pk, new master fuse and the car still won’t hold power.
ANSWER : Hi there. The only thing that I could think possible is causing your problem is that something may not have been correctly installed while your son was completing this maintenance. However, if your engine was difficult to start before this service, it’s possible there are different components that are damaged that simply didn’t resolve the issue. The only way of knowing what is going on with your Trailblazer would be to have one of our mobile mechanics in your area come to your location and complete a car is hard to start inspection.

It cranks doesn’t start new batteries, oil pressure switch new pmd, new injection pump. new alternator, new glow plugs.
ANSWER : Hello.

A crank but no start condition can be caused by many things. A few common causes are a faulty crank position sensor, or issues with the fuel system. The crank position sensor is used in the engine’s fuel calculations, and in some cases it’s failure will disable the engine.

It may also be possible that there is issues with the fuel system that are preventing the engine from running. If the fuel pump or injectors have an issue the engine may not run correctly, or at all. It may also be possible, for either case, that the issue may be wiring related.

I would start by trying to determine if the engine is getting fuel and then going from there. If you need assistance with these checks, consider YourMechanic, as one of our mobile technicians can come to you in order to diagnose your starting issue firsthand for an accurate repair.

Belts are cracked and need replacing, okay to leave off a/c belt?
ANSWER : Hello. If the belt driving the A/C compressor only drives the A/C compressor and nothing else, you can remove it with no consequences. The fan shroud is not optional equipment however as it has both a cooling system function and a safety function.

Depending on your climate, you might consider diagnosing the A/C system and repairing it. If you use a service such as YourMechanic, it will often be economical enough to do it, particularly if the fault is limited.

Even if the compressor shaft sealing is leaking (would be likely after 25 years), that is fixable in the field. Feel free to contact YourMechanic if you have additional needs relative to this or the replacement of your power steering, alternator, A/C belts.