What are the symptoms of drive belt pulleys being out of alignment?
I have a belt on the alternator pulley that vibrates like crazy at idle, and from this produces an annoying humming sound that is heard loud and clear in the cab. I have a 04 4cyl 5spd king cab frontier.
To go along with that, my alternator belt is worn significantly on one edge. These belts were just replaced in February to fix this problem.
Dealer failed late last year to torque a bolt holding the alternator on and this bolt came out and the alternator still funtioned properly and did not loss tension, however it was hanging on by one bolt, and I believe that the weight of the alternator stressed the bracket causing it to bend slightly out of alignment.
Think that makes sense and/or is possible??
What are the symptoms of drive belt pulleys being out of alignment?
I have a belt on the alternator pulley that vibrates like crazy at idle, and from this produces an annoying humming sound that is heard loud and clear in the cab. I have a 04 4cyl 5spd king cab frontier.
To go along with that, my alternator belt is worn significantly on one edge. These belts were just replaced in February to fix this problem.
Dealer failed late last year to torque a bolt holding the alternator on and this bolt came out and the alternator still funtioned properly and did not loss tension, however it was hanging on by one bolt, and I believe that the weight of the alternator stressed the bracket causing it to bend slightly out of alignment.
Think that makes sense and/or is possible??
It's possible it bent the bracket I suppose, but I'd suspect the alternator bearing first.
I realized that Jasper sent me the wrong engine (a 250cid vice a 200cid) for my 6-cyl Mustang only after I had put it in the car. It looked very similar, but the accessories didn't line up. Within 50 miles I threw the power steering belt twice. Once I got it lined up with shims it was fine.
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Jerry
2004 Frontier, King Cab, XE, 4x1, 4-cyl, 5-spd My Frontier Page
It's possible it bent the bracket I suppose, but I'd suspect the alternator bearing first.
I realized that Jasper sent me the wrong engine (a 250cid vice a 200cid) for my 6-cyl Mustang only after I had put it in the car. It looked very similar, but the accessories didn't line up. Within 50 miles I threw the power steering belt twice. Once I got it lined up with shims it was fine.
Third person from three different forums to tell me it is possibly the bearing.
How would a bad bearing be causing the belt to vibrate like this? Trying to picture it and just really not sure.
Third person from three different forums to tell me it is possibly the bearing.
How would a bad bearing be causing the belt to vibrate like this? Trying to picture it and just really not sure.
The bearing allows for rotation of the pulley shaft, but it also keeps it in place. If the bearing is damaged/worn it won't keep the shaft in place.
It's kind of a weak analogy, but imagine loosening all of the lug nuts on one of your wheels to just 1/2 turn before they make contact with the wheel. How badly will that tire wobble/vibrate as you drive down the road? How badly will the tire wear?
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Jerry
2004 Frontier, King Cab, XE, 4x1, 4-cyl, 5-spd My Frontier Page
The bearing allows for rotation of the pulley shaft, but it also keeps it in place. If the bearing is damaged/worn it won't keep the shaft in place.
It's kind of a weak analogy, but imagine loosening all of the lug nuts on one of your wheels to just 1/2 turn before they make contact with the wheel. How badly will that tire wobble/vibrate as you drive down the road? How badly will the tire wear?
Thats what I was wondering about. Trying ot figure out if it would be a loose fit. But, why might it be fine at different rpms? I think I can picture it, but don't know if I am picturing it tirhgt as to why it would run smooth at different rmps.
Thats what I was wondering about. Trying ot figure out if it would be a loose fit. But, why might it be fine at different rpms? I think I can picture it, but don't know if I am picturing it tirhgt as to why it would run smooth at different rmps.
thanks
I'd take the belt off of the alternator and turn the alternator by hand (engine off of course). See if the rotor turns smoothly. You can pull and push the rotor to see if thee is significant axial play. You can relax the belt tension temporarily and see if the roughness changes, either in magnitude or rpms (you might even remove the belt entirely and run the engine briefly to verify that it truly is the alternator or other belt driven accessory). A bad bearing can cause vibration at different rpms as the rotating assembly passes through different vibration resonant frequencies.
Actually, with the symptom of wear on one edge of the belt I'd vote for a misalignment problem.
If your belts are way too tight it will ruin the bearing over time and cause an imbalance. Does your truck have a spring loaded tensioner or do you tighten it manually?
I'd take the belt off of the alternator and turn the alternator by hand (engine off of course). See if the rotor turns smoothly. You can pull and push the rotor to see if thee is significant axial play. You can relax the belt tension temporarily and see if the roughness changes, either in magnitude or rpms (you might even remove the belt entirely and run the engine briefly to verify that it truly is the alternator or other belt driven accessory). A bad bearing can cause vibration at different rpms as the rotating assembly passes through different vibration resonant frequencies.
Actually, with the symptom of wear on one edge of the belt I'd vote for a misalignment problem.
Problem is, I don't have any time right now to yank the belt off and check it, or even loosen it. Two more weeks of classes, and I am swamped with exams and papers I have to get done and then still work a full time job. LOL I got an appointment for Tuesday. But I really wish, I could check it myself before I take it in. Makes sense about what you said for the vibration at different rpms. Thanks man
Maybe I'll find some time to take a break and run out there to at least loosen the belt and see what happens. I wish it was easy to diagnose a bad bearing vs. misalignment visually
If your belts are way too tight it will ruin the bearing over time and cause an imbalance. Does your truck have a spring loaded tensioner or do you tighten it manually?
- Greg -
Yeah, I learnt that the hard way in 2004. I was a couple of months away from getting married and my alternator went bad on my 01 Elantra. I thought I would repalce it myself to save money since I was getting married and all. Put the new one on, and starting getting paranoid that the belt was tight enough. I would go just a little tighter, but nope, still paranoid, and on and on. Week and a half later damn bearing went bad. Had to start all over again.
But no, it has to be tighten manually. I was wondering one time what the tool used to measure the tension on a belt was called, but the tech told me they just usually get it just tight enough. They see those things all the time, they usually have a good idea of whats good and whats too much, so I kinda trust them with belts. But you do have a good point. When I brought the truck back to the dealership after that bolt came out, I dropped it off the night before, and left a very mean letter expressing how pissed I was about the incompetent tech that failed to torque the bolts. I wonder if it was the same guy, and he got scalded, became pissed off, and not intentionally trying to damage property, but because of anger was tightening down the bolt and just put too much tension on the belt. who knows...
Yeah you definitely have to be careful with tightening belts. I find it's best to go looser than you want and wait for them to squeal, then shut it off and tighten them one or two turns and see if the squeal went away. The alternator belt is an easy one to check because the AC compressor is usually on the same belt. Just turn your AC to try and make the belt squeal. Overtightening the belt is worse on the water pump belt because it's really easy to screw up the WP bearing.
I wonder if when the pivot bolt fell out your alternator was out of alignment and it warped the pulley or bent something else just enough to cause this problem. When they fixed everything did they replace the whole alternator?
Yeah you definitely have to be careful with tightening belts. I find it's best to go looser than you want and wait for them to squeal, then shut it off and tighten them one or two turns and see if the squeal went away. The alternator belt is an easy one to check because the AC compressor is usually on the same belt. Just turn your AC to try and make the belt squeal. Overtightening the belt is worse on the water pump belt because it's really easy to screw up the WP bearing.
I wonder if when the pivot bolt fell out your alternator was out of alignment and it warped the pulley or bent something else just enough to cause this problem. When they fixed everything did they replace the whole alternator?
- Greg -
Those jokers simply put a new bolt in and made sure everything was torqued that they have ever touched, as per my pissed off written instructions left for them the night I dropped it off. I can't wait for Tuesday to come, not so much as for getting the problem fixed, but more so for how they will treat me and my truck. I'm ready to go off on them and call Nissan USA again if they try to give me more crap. Everyone says this all the time...I don't work my ass off while going to school full time to pay for a vehicle that has problems. I didn't buy a vehicle from this particular dealer to be lied to and have sub-par work done. If I could get rid of this truck without taking a loss, and buy a different one, I would. But right now, I wasted too much money to sell the truck and buy a different one. Besides, I've become too attached to it now. I'm thinking if I can get this and all the other problems fixed, it will be the last time I take the truck in to the dealership. Hopefully nothing else will go wrong during the warranty.
I was just out at the garage and a neighbor had been pulling into his garage, so I asked him for his opionion on my pulley issue. He watched the belt vibrate with the loud humming. His opinion, bad bearing.
How credible is he? Don't know, but it goes along with what you guys are saying and you guys haven't seen it. So, I'm pretty confident now that you guys were right about the bearing and not being compeletly an alignment issue. Thanks and I let you know how it goes Tuesday at the dealership.
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