C220 CDI W203 - Help

[Wully]

I have just purchased the above from a non-mb garage and was told that the alternator was to be replaced at it's service.

Now i've had a look under the bonnet and as i'm new to the oil burners i have a couple of questions that i hope someone may be able to answer.

1) What pulley is the alternator - One on the far bottom left?
2) When at idle should there be any movement on the cam belt? ie bouncing up and down at the top of the belt?
3) There is a small pulley in the middle of the rest that i think maybe the power steering pump, should this twist from left to right when at idle?

I've attached a pic that i took from the russian site and marked the pulley refered to in question 3.

I'm planning to take the car back to the garage i got it from but i need to be armed before i go so i'd appreciate any help you can give.

 

[jimmy]

Not too familiar with the 220CDi engine myself but I know that it does not have a cambelt but a timing chain. The belt you are referring to is the auxillary drive belt and only drive auxillarly equipment, your engine would not suffer damage if this belt broke.

Looking at your picture, the crankshaft pulley is the main, large pulley at the bottom, this is the main driving pulley that supplies power to the other pulleys. The A/C compressor is the top right one and I would say the alternator is the bottom right one. The small centre one looks like the tensioner, does it have a spring and shock absorber attached to it?

 

[230K]

Hi

I am fairly sure that that is your drive belt tensioner pulley, they do need replaced at times and if it is flapping about it probably does.
Bear in mind that this is designed to move to take up slack in the drive belt but if the bearing in the wheel is causing it to slap about then it needs replaced.

Oh this belt in question is not your cam belt, you dont have one just a chain that is out of sight.



230K

 

[Ian B Walker]

Bottom left is altenator, bottom right is a/c. Top right is power steering, arrowed pully is the tensioner, top left is an idler pulley, above crankshaft is the water pump

 

[Wully]

Told you i didn't know much about oil burners!

Regarding the pulley being a tensioner, there seems to be movement like in a twisting sort of way and belt is what can only be described as bouncing.

 

[Ian B Walker]

So you are saying that when the engine is not running you have movement in the belt? If so I would have the belt changed and also have the tensioner looked at. I read that the altenator is to be changed, if so have the belt renewed at the same time. false economy to put the old belt back on. If the engine is running then yes there will be some visable movement in the belt, but not a lot. I honestly think your problems stem from a worn tensioner.

 

[Wully]

When the engine isn't running the belt seems tight, when the engine is running the belt seems to bounce up and down on the top pulley.

The alternator was suppost to have been replaced but i doubt it, going to have a better look shortly.

 

[silverarrow]

has been faulty tensioners and pulleys

 

[tamrsoft]

The pulley you have marked is the tensioner pulley, it is a self contained self-tensioned unit and is easy to replace, they are normally quite robust on these engines. Your dealer is refering to the alternator pulley which has a free-wheel clutch inside it on 220 CDi models and has a tendancy to seize up and needs to be replaced. Symptoms are rough idle and flapping drive drive belt at idle, it is easy to check, just remove drive belt and check that pulley freewheels in the ACW direction but turns the alternator shaft in the CW direction. If your dealer is trying to get you to replace the whole alternator because of the pulley - just find another dealer.

 

[Wully]

So basically what you are saying is that the tensioner could be fine but because of the alternator pulley this could cause the flapping belt?

Regarding the alternator, the pulley can be changed independantly of the alternator? Is the actual pulley wheel part of this?

 

[tamrsoft]

Yes, I have a similar problem and the tensioner is fine but the free-wheel clutch in the pulley is seized. It's a known problem on which MB has published a service note. The pulley can be replaced by removing it with a special splined socket tool, I have been told it can be done with the alternator in situ but MB insist on removing the alternator to do it. I believe the job plus parts is about £130 at a good Indie. Check first to see if this is the problem, it usually is on these engines, and it would be a damn sight cheaper than a new alternator.