Hello,

I have a Mitsubishi Outlander 2008, with a 4B12 Petrol engine.
Recently i have come across the issue of my Serpetine belt running off; it seems to be slipping off, sometimes just one "tooth" and sometimes it just flies off.

My car has some milage, about 300.000km.
When I first came across the issue I changed the water pump (the car also had overheating issues), i changed the serpetine belt for a OEM one, same issue, i changed to a aftermarket one, same issue.
Then, couple weeks ago I changed out all the Idler pulley's and the automatic tensioner. The problem seems to be a bit less agressive, but still the belt has already run off a couple of teeth. It seems to be coming from the top; somewhere around the power steering pump, but i have checked with a straight edge and it seems to be inline.

I dont have any picture's as the whole system looks "normal".

Does anyone have any advice as what to do next? I just dont know how to fix the issue, and no mechanics have any time next couple of weeks, and i will be taking the car on a roadtrip in 3 weeks.

I cannot find a post with the same issue, put if there is, please note it to me

thank you guys!

 

you said you replaced the tensioner pulley and idler but it is still happening? take the belt off and grab each pulley and give it a wiggle. See if there is any play in the alternator, power steering, and even the crank pulley. I have a feeling that either the damper in the crank pulley or the bearings for one of the others has started failing.

 

Hello!
Thank you for your reply;
i have tried today and there seems to be no real play on anything; the only play i could find is the power steering pump pully being able to move "in and out" for a couple of millimeters, is this normal?

Are there no ways to align or misalign the whole serpetine belt?

 

If you are happy with the pulley side play then check that none of the accessory (Alternator, AC etc) mounting brackets have got bent? Check alignment in relation to each other as any slight twist will tend to drive the belt of centre.

 

I am having the same problem with the serpentine belt slipping off. Were you ever able to solve the problem?

 

Ah sorry i forgot to update -
I ended up replacing all the serpetine rollers, the tensioner and the power steering pump.
And I think this is the step that worked: I sanded the rollers so that they are really rough.
After that I never had any issues with the belt.
So if you have the same problem I would probably advise on replacing the rollers (sanding them so they are rough), and putting a new belt on.
I think sanding the rollers helps with keeping in it path, until the belt has worn a path into them . I hope this is helpful.

OH ps, just remembered., there are different kind of belts in the same specification; some have deep V shaped grooves and some have U shape grooves.
I just orderd like 4 different brands and put on the one with the deepest grooves, so the belt is "deeper" on there.

 

Thanks for your reply. I will try that. Thanks again.