Hi everybody,

I have just been through absolute hell getting the local Mercedes dealer to repair a tensioning fault on the big belt that runs the alternator (amongst other things) on my car. After the 3rd trip back in and a 2nd bill I thought they had fixed it and all seemed well until I got home and noticed that the power steering is much much heavier than before when driving at town or parking speeds. Before the repair the steering got lighter the slower you went and it could be turned very easily whereas now it really takes a bit of effort to park the car.

I'm no expert but I understand this belt also runs the power steering pump and upon inspection it seems perfect. I was hoping somebody on here has had a similar problem or knows how the dealer could have fitted the new belt or tensioner wrongly to cause the pump not to run properly.

In case it helps the parts they replaced are as follows:

Spring: Part #: 001 545 01 09
Belt: Part#: 011 997 85 92
Belt Tensioner: Part #: 604 200 02 14

I really would be grateful of any advice as this dealer is absolutely hopeless! They want over a months advance notice for a booking (even though the repair is one they didn't do correctly before) and then claim nothing is wrong with the car when you go in with it! At least if I have a rough idea what could be wrong I can perhaps pursuade them more easily tomorrow.

Thanks very much in advance.

Greetings,
Michael

 

it's a backjob, and must be done without the booking list entry.

was it using a serpentine belt? the routing must be wrong.

 

Could too much tension on the belt be causing the pump to run erratically, or not in a smooth manner, making his steering stiffer?

 

Hi,

Well, after waiting for my appointment at Mercedes I got my car back with a report saying "no fault found" so wasn't so pleased. I debated the issue with the mechanic but as far as he was concerned the steering turned and my car was old (1999!) so the steering is perfectly acceptable.

I guess I'll just have to put up with it and hope all is okay!

Regards,
Michael

 

it could be the guy who put your belt selfajust tensoner some how wrong ,try to re install the tensoner before put in your belt .if you dont trust the dealer ,try to got the belt # call in the other dealer or part store see you got the right part.
iwhen i put the belt ,i never use tool i just pull up the belt and snap in the pully

 

Hi again,

Thanks so much to everybody that has replied so far...your help is greatly appreciated. I'm sorry to keep going on about this problem but the main dealer in Brussels annoyed me so much at the time of the repair by arguing with me, basically doing nothing and overcharging I really want to get my facts completely straight so I can get it sorted. It's even more annoying as I really was sure there was a problem from the moment I collected the car last month but what can you do when the service manager just stands arguing that you're imagining it and refusing to do anything!

Tonight in Edinburgh there was the first real cold and wet night the car has been out in since the repair. The problem seems to be getting worse as the symptoms now are more pronounced. I discovered a trick with the climate control which gives a "volt" meter on the screen by holding down the "rest" button which has helped me diagnose the problem.

Basically, I did the following test. If you are stopped with the engine idling, your foot on the brake and the indicator on the voltage drops down to about 10v, the indicator starts flashing ultra-fast (I guess due to the low power), the instrument lights/headlights dim and the steering gets heavier. The moment you rev the engine a little the voltage goes back to normal and by testing it I now notice the steering gets gradually lighter but the moment the engine drops back to idle everything screws up again. I tried the exact same test with the engine off & the key in position 2 so everything is just running from the battery and the indicator flashes perfectly. I'm not an expert but I'm learning (thanks to all of your help) so my conclusion is that for some reason the belt isn't spinning at the correct speed when idling and as it drives the alternator and PAS pump the results are shown by the heavy steering and low power. Furthermore, the fact all is ok when the devices are running from the battery shows the battery is okay and the fact that it is ok when you rev the engine a little shows the PAS pump & alternator work okay meaning the problem is with the belt driving them.

I would be so so grateful if some of you could give me your opinions on this and let me know if I sound like I'm concluding the right thing. Also, if anybody has an idea how they could have screwed up fitting the belt, tensioner shock absorber & spring that it would cause these symptoms it would really by such a HUGE help as I can go to Mercedes with a complete description of the problem and it's cause hopefully resulting in it finally being fixed!

Once again thanks so much for all the help - if we ever meet I'll owe you all a drink!

Greetings,
Michael

 

... like you say is just 10v means your alternator getting old to be change ....
you can try to testing again ,when step on break with your left foot ,use right foot step on gas pedal at the rpm around 1200.then turn the wheel ,if seen ok with that rpm speed ,mean you dont have power at the pump speed.
by the way try to charge up your bettery that (use the shop charger )before testing.....
good luck...

 

Thanks for the tip...I'll have a look at the battery as well.

However, I just had a thought about what the problem could be. The dealer replaced a tensioner spring, shock absorber and the belt but not the actual tensioner. Could it be the actual tensioner pulley isn't turning easily enough resulting in an increased load on the belt? The more I think about this the more it makes sense - it explains the squeeking when cold (perhaps the pulley itself), the heavier steering/power problem (caused by everything turning a bit slower) and the WD40 could have temporarily fixed it because some got inside the pulley bearings free-ing it up but now it's wearing off resulting in the problem worsening. Does this make any sense? Is it even possible?