Hi The idler pulley on my 1999 773 is showing age , I'd like to know if I can change the automatic tensioner for a manual one the difference in price is humongous!!! I've read somewhere that certain models of the 773 had old fashion tensioners. What are the risks and tribulations? Thank you all in advance for your feedback and allowing me to continue to use my Bobcat.
If you are talking about the pulley that tensions the fan belt - that design was a joke, imo. I simply take about a 6" long spring and install it so it pulls back towards the gate. Cheap but effective.
I don't know the 'right' answer to your question, so this is just speculation: Diesel engines don't operate as smoothly as their gasoline brothers, and there can be, at times, dramatic fluctuations, like at shut down where diesels stop so much more quickly at the last revolution than gas engines do (much higher compression). See the video links below, which pretty much tells the story. I've read reports of owner's drive belts snapping and even alternator shafts breaking (on a diesel), and personally, I've experienced a dancing belt (and a lot of nasty noise) like the video below from a faulty alternator pulley on a diesel vehicle. That's one reason they put a shock-absorbed spring tensioner on a lot of diesel engines, and alternator clutch (to reduce 'shock'). I suspect that the spring loaded tensioner on your skid loader is there for the same reason, or as a sort of safety-valve, or a fuse if you will, to help smooth out belt action and prevent breakage in a worst-case event. If that's the case, if you remove the spring tensioner, then you're relying on the belt to absorb the fluctuations. You wouldn't want to experience a snapped belt because at *best* you're going to overheat (hopefully you'll catch it), but the belt could get wrapped up and damage the radiator. So, in that way, if that ever happened, it would make the spring loaded tensioner look mighty inexpensive. Again, I'm just speculating but it's based on my experience with other diesel engines I've had and worked on, so talk to a Bobcat mechanic ...a good one, or engineer and see what they have to say. It might be that a manual tensioner is just fine for 90% of the time but results in significantly reduced belt life ....and the spring loaded tensioner was added to extend service life and reduce the "risk" of damage and failures that may have been showing up in Bobcat service departments (and costing Bobcat enough to justify the added expense). It probably cost more so there must have been a reason to do so. So I guess you need to weigh the cost/risk/benefits. Again, I'm just trying to talk through the question, so take it for what it's worth. But one things for sure, having been involved on the manufacturing end of things for many years: manufacturers only invest in a change to resolve an expensive problem or gain a competitive advantage. They didn't change it because it makes them feel 'good'. Maybe adding one of those diesel alternator belt pulleys in addition to a new spring tensioner would smooth out the belt action even more and dramatically extend the life of the new tensioner. Both are pretty much standard on modern diesel vehicles. Dancing Belt Video: https://www.youtube.com/watch?v=4EXYP1CmL9Q Here's another: https://www.youtube.com/watch?v=5qHVL1EMd34 ..and a couple more: https://www.youtube.com/watch?v=gU5KO3OG1iQ https://www.youtube.com/watch?v=rXehCcNzq_A If your tensioner is failing, that might be a sign that it's doing it's job and just reached it's design lifespan. If that's the case, bite the bullet and buy a new one because it's doing it's job. If the pulley bearings are wearing out, I've had success removing the pulley on several of my vehicles and gently picking out the cover with a small pick (pull from the center), re-greasing and popping the cover back on ...as a matter of periodic maintenance (while the bearings are still good). If ya booger up the cover a little, just put a dab a bit of silicon on the dinged area, the grease gets slung to the outside of the bearing while in use. Seems like there are quite a few people that do this (from what I've read on forums) to prevent failures.