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Belt Tensioner Blues

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Had quite a drive up to Rondeau Provincial Park in Ontario over the Victoria Day long weekend.  Worked all day at a new Amazon fulfillment plant installing the elevators while DW packed up the MoHo so we could just basically leave when I got home.  That part worked fine, unfortunately about halfway there, or about an hour and a bit into the trip, I notice the stop engine light and check engine light at lit.  For how long I can’t say exactly.  My coolant temp guage is on the fritz some days, and it was that day.  Anyways, pulled off to the shoulder on the 401 and opened the hatch in the closet.  Serpentine belt came off, but still in tact. Reservoir tank is boiling over onto the asphalt. Not good.   Me being a newbie coach owner learned the hard lesson of keeping spares, as I did not have one on board.  Turns out no one did because noone was open at 6 on a Friday of a long weekend. 
I decided to reinstall the belt and see what happens.  Made it about a kilometer and the belt fell Off again. Pulled it off to the side of the 401 again and decided to try and get a tow.  Unforgivably no one was able to tow us. We tried every place within a 250km radius.  No one could help as they either weren’t open, stopped doing weekend service calls or were just not willing to tow it. 
So I put it back on and waited for a clear stretch of traffic and managed to limp it to the park at around 11:45 at night.  We had planned to show up at around 6:30.  During that time the belt had fallen off 4 more times, as my saving grace was the BlueFire App I had the wife watch the temperature like a hawk during the travel.  What a great tool. This thing literally saved my A$$!

In the end we had a pleasant stay at the site, and it wasn’t until I was at the Canadian Tire parking lot on Monday (as they were literally  the only ones open)I discovered the underlying issue.  The belt tension was not sitting aligned with everything else.  It was quite clear in the daylight.  Everything felt firm, the pulley spun freely, as did all the other ones.  The reason it was cocked is because the M10 Gr.8 bolt that holds it on was slightly bent at the threads.  How does that happen?? I still can’t figure it out.  There is no sign of a mechanical binding or anything anywhere. Any input would be much appreciated. 
Anyways, bought some standard M10 hardware and was able to replace the bolt with a modified one. Got me home without incident. 
New belt, tensioner and water pump for the heck of it should be ready for pickup tomorrow. 😉

Thanks for reading!  


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Hey brad… lot o miles or years on the rig? Better look at the alternator bearings, plus IF your gonna do the water pump, dont forget the T stat, and coolant filter, just sayin… in for a penny in for a pound… or just rebuild the cooling system!

when i had to replace my radiator i did it All, im cheap an lazy, i live by “buy once, cry once!” My rig weighs 32k lbs.” an i pull! I didnt want to have to get back in it somewhere on the road🙀🤦‍♂️
just sayin

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There is not a recommended change interval for a belt tensioner but there is an inspection method listed in my engine service/repair manual.  Basically checking the idler pulley itself for play and/or signs of failure. 

One thing I do when I'm working on the engine is while running observe the tensioner/pulley.  The belt should run smooth.  Earlier this year I was working on my rig and noticed the belt tensionrer seemed to be "bouncing" more then what I remembered an/or comfortable with.  So I ordered a replacement and changed.  I did keep the old one as a spare, just in case, along with the old belt.  Just another thing you need to watch and be aware of.

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