Reanimation

So it's been like this since I got the car and after fitting new belt and tensioner. Had a look at my neighbors 270 s-class and his belt had no vibration at idle. So whats wrong.

91ser

Wow, that isnt normal!!

Did you replace the tensioner or the guide? There is one that is just a free floating pulley that also goes out, but it is not the tensioner.

Can you take the belt off and manually spin each component to see if any has inconsistent resistance? (ok, ok, dont try to spin the crank pulley)

Is there anything caught in the grooves of any of the pulleys causing it to jump?

91ser

Also, how much play is there in the belt when the car is not running? How much deflection does the belt have? It shouldn't have more than 1/2" or less each direction of play.

Reanimation

I replaced the tensioner with pulley(febi), deflection pulley(febi) and waterpump(febi) along with a new Continental V-belt. I did check the resistance and condition of the components before, Ive just been out and taken the belt off to check again and cant find anything wrong. I started it up and it was nice and smooth for maybe 15 seconds then it changes abruptly. The deflection seems fine not to tight or loose. Could anyone reading please check theirs.

Yidney

Not many people here will have that same engine to check, but I have just as long a run on my belt and it does not do that. If the tension is good, then I suspect one of two things - first, although the pulleys you replaced may run smooth, one may not be perfectly round. It may be either slightly oval, or it may be round, but not running on center. Or second, the belt has some heavy spot or other imperfection in it.

Reanimation

Appreciate the input, I might as well try a new belt and see what happens.

Paulmurphy

Alternator freewheeling pulley could be seized
it should turn free one way and turn the alternator the other way it takes out vibration in the belt

sailorben

If I recall correctly, once on my 270, I remember being able to fit the belt on in two ways. One way gave me too much slack. I could do the same on my 220 also. Made that mistake of not taking a photo of the belt path. Not again...

Reanimation

The pully on the alternator felt fine, but I could be wrong. how do you know this?

megacrazy

Why did you replace the tensioner to begin with? Was the same issue there before you replaced the tensioner?

The tension on the belt is obviously incorrect. Check all pulleys again. Sometimes damage is not visible unless you completely remove the pulley.

Seeing how the problem starts after 15 seconds or so, it's probably a pulley that's not visibly damaged or whatever was installed is incorrect or the belt is stretched etc etc.

Reanimation

Well I think its the Alternator Because the more I use the electrics the vibrations get worst then settles down again.

Paulmurphy

To check remove the belt hold alternator pulley and turn clockwise it should feel heavy,
Turn pulley anticlockwise it should feel very light almost no feel at all, if it is heavy both ways one way bearing is seized. That's assuming that 270 is a diesel, video sound like it.

Reanimation

Thanks, it goes tight in both directions so that's the problem, new pulley its is.

Paulmurphy

It can be bought separate and fitted without removal of alternator, but that requires a special tool.

Reanimation

Yeah thanks dude I've ordered a new pulley and tool kit, fingers crossed it gets my engine running sweet.

Reanimation

Fixed, New alternator pulley and the belt is smooth.

Paulmurphy

Nice one, super smooth now

ALFAitalia

When I had a similar wobble on another car it was not the tensioner or any pulleys...it was the cheap pattern belt which over time has softened a lot more in one part than another....new belt sorted it. Glad you sorted it OP.