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Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 20360
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have classthe drive belt is squeaking and a noise that

Customer Question

I have b class(###) ###-####the drive belt is squeaking and a noise that sounds like a sea lion changed all 3 pulleys on the tensioner and the water pump as there was a bit of play in that but still squeaking and sea lion belt off and all silent do you think this model has issue with crankshaft puly
Submitted: 25 days ago.
Category: Mercedes
Expert:  Matt replied 25 days ago.


I'd 1st examine carefully the condition of the bottom / crank pulley as these are composite construction with a rubber element and its possible this rubber is breaking up and allowing the two metal portions to move.

if the crank pulley is breaking up then this can create the squeak

also check all the pullies for a stone stuck in a groove or otherwise stuck debris and check that you have the correct belt fitted as if its too tight then it'll squeak

Customer: replied 25 days ago.
I assume to change this crank pull yo got to drop the engine
Expert:  Matt replied 25 days ago.


you are a little tight on clearance to the chassis rail but you can create space by removing the engine mount on this side and allowing the engine to drop down on a trolley jack to move the pulley away from the chassis

Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 20360
Experience: BEng hons Mech engineering, in auto industry 22 years
Matt and other Mercedes Specialists are ready to help you
Customer: replied 25 days ago.
Also when you are driving you can feel in car speeding up and slowing Down engine fault code is a generic code p0068
Customer: replied 25 days ago.
I take it when I rate that's it convocation over
Expert:  Matt replied 25 days ago.


to get that code then the squeak may not be the belt?

as the code relates to a possible air / vacuum leak

after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.

if the engine condition is the same then chances are the meter or the connection to it is faulty

It’s also worth cleaning the MAF sensor wires, as they can get coated with dirt over time which then offsets the reading

Use some contact cleaner or brake cleaner to spray onto the wires to remove the dirt – on no account touch the wires with anything as they are very fragile

Customer: replied 25 days ago.
Where is the mac sensor on this thing I can't find it ��
Customer: replied 25 days ago.
Maf not mac
Expert:  Matt replied 25 days ago.


The MAF is located on the inlet tract , if you look just after the air filter box then you should find it

Customer: replied 24 days ago.
I think I'm going to have to do the live chat with you on the weekend when I've been paid if that's ok
Expert:  Matt replied 24 days ago.


Customer: replied 20 days ago.
Thanks for your help mat removed air box and throttle body and could see maf sensor was covered in oil from the breather in the throttle body little bit of spray cleaner reset code and runs great again
Customer: replied 20 days ago.
Crankshaft puly today so don't go on holiday on me ������
Expert:  Matt replied 20 days ago.

no problem

just get back to me on this post and I'll help if I can

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