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Noisey drive belt, possibly alternator, belt

Mercedes a160 1.6 petrol, non air con model.
noisey drive belt/pulley noise at idle, gets worse with increased revs.
suspect bearing on alternator, belt tensioner or idler pulley.
dont think it's the water pump, not a typical noise of a water pump, its more of a whining noise than a screeching noise that you would get from a water pump.
these cars are on a timing chain so the noise rules that out!
are you aware of what it is most likely to be? i've been told that these cars are a right pain to work on!!! can i change the parts without dropping the engine?

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  • yadayada
    yadayada May 11, 2010

    what is the question here, you have answered it already, the drive belt or the pulley's


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Sounds like idler bearings but you have to release the tension to check,Also you can check the rest of the pulleys also at this time. I dont think you have to drop the engine.

Posted on Oct 06, 2009

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Screaming noise coming from motor gets louder as rpm changes gears sounds like something screaming

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Makes squealing noise

You need to check the belt that drives the alternator for proper operation. The belt may be old and worn, or a pulley may be not freewheeling, but seized or with a bad bearing. Possibly the tension on the belt is too loose from a worn out tensioner.

First, spray a little water on the belt with engine running and see if noise goes away, possibly a worn belt. Pull the belt off and check all pulleys. Spin them by hand and see if spins easy, no rough feeling or a catch when spun. Check alternator pulley, idler pulley, tensioner pulley, PS pump pulley and A/C compressor pulley-check them all for free wheeling. If good check the tension on the belt when installed. If unsure, have a mechanic check tension with a belt tension tool.
If belt is good and pulleys good, check alternator output with a voltmeter on the battery with engine running. If voltmeter is below 13.5 volts, the charging system is still not working properly. Have it checked out.

Sep 29, 2013 | 2000 Mitsubishi Galant

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Hello! I have an 06 Trailblazer and its making a loud whinning noise. It gets louder when i press the gas pedal. We have replaced the idler pulley along with the belts. We have also taken the alternator...

Have you tried running the engine for a minute with the belt removed? If the noise is still present when you do this, then it is not related to the belt or any of the pullies. I have seen "whining" noises coming from the air induction system - namely, vibrations set up by the idle air control and reverberating in the intake. This will not go away with the belt removed.

If the noise does go away with the belt removed, then the problem HAS to be one of the pullies or components that are driven by the belt. Power steering pump a little low on fluid maybe? Or possibly a rough bearing in an idler pulley? Spin each pulley by hand and see if it makes any noise. You should not be able to "hear" them spin. If you get any kind of rattle or roughness when spinning the pulley by hand, then this is most likely your problem-child.

Oct 05, 2011 | 2006 Chevrolet Trailblazer

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Sqeaking from the accessory belt drive. could be a bearing in one of the pulleys, the pump, the alt or the belt tension has weakened. It occurs off and on, usually just off idle but sometimes at idle. Is...

common cause is the belt gets worn and stretched, yes the tensioner is suppose to keep its tension but also the tensioner gets weak and all it takes is a couple slips of the belt to harden and you will get a squeal. Spray WD 40 on tensioner, idler pulleys, alternator behind pulley, not on belt or where belt rides on pulleys but at all bearing locations. Did squeal stop? If not replace belt. Usually a chevy water pump will leak, or grind not sqeak unless there is rusty non lubricated so called coolant in it which 1974 maybe but 2007 na im sure you didn't neglect this baby. You can also inspect the belt carefully, possibly buy a can of belt dressing and spray belt but do make sure you use a ratchet and check your belt tensioner for smooth non sticky tension pressure.

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My dodge sprinter 213 cdi with AIR CON though

Over to right pulley (bottom the a/c) then over rider pully to top left pully to alternator to fan down to drive to tensioner

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Squeaking noise front drivers side of engine

Loosen the belts [ you do not need to remove] so they are free of tension to all pulleys.Start engine , if noise goes away either belts were too loose [ common on lx 450] or you have a worn & noisey pulley /bearing.have seen idler pulley below alternator have dry / noisey bearing.Otherwise if idler is ok it has to be another belt driven assessory , ac clutch,water pump & or fan clutch.Good Luck.

Jan 17, 2009 | 1997 Lexus LX 450

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Sounds like there are two possibilities.

A slipping belt that drives the alternator or the air conditioning can cause a horrible squeal. I am not sure if the Corrolla has a single belt or two belts. They drive the Water pump, the air conditioning and the Alternator off of the main crank shaft pulley. If so these belts can all be adjusted.

If there are two belts - one will drive the AC and the other will drive the Alternator. If its the Alternator belt that is slipping it should get worse if you tirn on the head lights and the rear window defroster as these draw power from the alternator and make the alternators job harder. If its the AC belt that is slipping then when you turn the AC on it should get worse. If you only have one belt then turning anything on should make the noise worse.

Typically to adjust the belt there is an adjuster nut on the Alternator assembly. You typically have to loosen the mounting bolts on the alternator slightly prior to stretching the belt and putting more tension on it and then re-tightening the bolts once the belt is tighter. Depending upon when the belts were last changed it may be time to replace them.

Getting to the bolts on the engine to do this work can be tricky and will be easier if you are familiar with the location of the components and the location of their mounting bolts. Really the best way to work this out and to get some idea is to go to a local car parts place like Autozone and buy a manual for the car (about $20) and this will be a huge help for this minor repair and many others. If these belts haven't been replaced in the last 30000 miles it would be a good idea to buy and fit new belts at the same time. New belts are about $30 foryour car although if the belts are not worn and cracking then re tensioning should be the best option initially.

The belts should be tight enough such that you can only twist the belt through a quarter of a turn on their longest running length.

The alternative that may be causing the squeeking though is worn breaks - where the pads have reached the wear limit warning and a metal spring is now rubbing on the surface of the Break disc. In that case you need to change the pads, but the symptom you describe sounds more like loose belt.

Hope that helps.

Aug 17, 2008 | 2001 Toyota Corolla

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