illanrob Posted July 30, 2011 Share Posted July 30, 2011 Notice a humming sound from the engine while parking in the garage, then openned the hood while the engine is still idling, and sounds like its from the alternator, and there is a slight burning smell. Started the engine the next day, can 't say that the humming is still the same loudness or less. Maybe the 100F temp made it louder while the 80F garage is quieter. Got a stethoscope later to listen to all top engine bearings. Sure enough the alternator rear bearing has more noise than any other bearing such as front alternator or, power steering. Remove the belt and spun the alternator pulley by hand and sure enough the rear is noisy without the stetoscope but not horribly so and there is no play in the pulley/shaft. The alternator burning smell is not so much Has anyone just tried to grease the alternator rear bearing with good results for noise? Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 30, 2011 Share Posted July 30, 2011 Should be a sealed bearing (and a very cheap, small bearing at that). I woukd just replace it. Unlikely that adding grease will help. GD Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted July 30, 2011 Share Posted July 30, 2011 if you can ID the bearing you can probably pick one up for $6 - $8. but the trick is figuring out which one it is. my best advice, short of swapping in another used ALT is to remove the bearing and take it to a parts store and match it. the r&r of the bearing is the same labor as trying to re-grease it, i would think. Quote Link to comment Share on other sites More sharing options...
illanrob Posted July 30, 2011 Author Share Posted July 30, 2011 GD, I saw a U-Tube video on replacing alternator bearings including using a plastic injector with needle to add grease to what appears to be a new sealed bearing, since I could not see the balls in the bearing. The video also showed how to pin the alternator brushes for the rebuild looks encouraging. Replacing a pressed bearing requires a press. I figure that greasing the bearing is a first easy step. Servicing Sub alternators seems an easy job. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 30, 2011 Share Posted July 30, 2011 Replacing a "pressed" bearing of that size does not require a press. A socket and a hammer will do just fine and a two-jaw puller can be used for removal. I used to rebuild motors all the time when I pulled wrenches on industrial machinery for a living. Small alt bearings are childs play - a press is like killing a fly with a shotgun. WAY overkill. I own a press and wouldn't use it. Sealed or sheilded bearings are greased from the manufacturer. People do lots of things on you-tube that they really shouldn't do. Dissasemble the alt, write down the bearing numbers, and get replacements from a bearing supplier. Simple as that. GD Quote Link to comment Share on other sites More sharing options...
idosubaru Posted July 31, 2011 Share Posted July 31, 2011 you can regrease the bearings. a needle fitting for your grease gun and some dental picks to be able to gently pry the covers up enough to insert the needle. i do it on XT6 timing pulley bearings since the pulley kits are $400. it works fine and they feel like brand new bearings when done. noise, as you know is from lack of grease. you want to be sure not to overfill as the grease will come out and even push the seal out with centrifugal force/heating and expansion. but - it's pretty much a waste of time since you can just replace the bearing like GD said. it's difficult to do it without compromising the seal at all, so you're likely to end up with a less reliable bearing. Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted August 1, 2011 Share Posted August 1, 2011 The flies around here need a shotgun they are that big. At that many miles, your alternator is not going to last much longer for charging. A fine needle end grease gun is probably all it will take to quiet it, its just getting dry and telling you so. Get some lube in it, good to go. Quote Link to comment Share on other sites More sharing options...
Cougar Posted August 1, 2011 Share Posted August 1, 2011 Frankly, in my opinion, if the bearings are that far gone to require some lube you are better off to just replace the alternator with a rebuilt one. The bearings are now damaged anyways and it is too time consuming to tear into one an work on it. If you do still decide to fix it then I recommend you have it checked out first doing a load test. More than likely there are some bad output diodes in it. So even if the bearings are replaced you may have a faulty alternator. Quote Link to comment Share on other sites More sharing options...
illanrob Posted August 5, 2011 Author Share Posted August 5, 2011 The alternator was noisy, had a burning smell, the bearings were both worn (they would spin on their own like a bicycle wheel, say one extra turn or so unlike the new bearing which just do not spin by themselves). Ended replacing both front and back alternator bearings with 190Kmi, $20 for both from an auto electric shop, after advised to keep the current original half worn brushes. I managed to give myself extra work disassembling the brush assembly anticipating that the 5MM by 8MM by 22MM brushes were a cheaper repair than the complete assembly, about $20. The hardest task in the alternator bearing disassembly was removing the front alternator pulley 24MM nut, followed by the rear small bearing removal with rather large axle size pullers. The front bearing just falls off, that was easy, and the rear bearing hammers on the shaft rather easy, 2 minutes. Another hard task was the soldering of the spring loaded brush wire tails and dressing the wires so the brushes spring out when the external retaining clip is removed after complete reassembly. Some photos for you all. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted August 5, 2011 Share Posted August 5, 2011 nice job and great pictures. thanks for sharing. you replaced bearings ($20) and brushes ($20) for a total of $40 on the rebuild? are those a generic size of brushes, could probably order them online now that you posted the size? Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted August 5, 2011 Share Posted August 5, 2011 Actually they are 5mm x 8mm x 26mm...... http://catalogue.alternatorstarter.com/ComponentPartDetails.aspx?Part=7304-2410&App=N I can't find anyone online that sells them although there is an ebay seller that sells the 7304-2412's ('95+ Subaru alts) for $1.95 each. They may also have the 2410's but you would have to contact them and ask. The other place I saw online wanted a minimum order of $100..... etc. GD Quote Link to comment Share on other sites More sharing options...
illanrob Posted August 5, 2011 Author Share Posted August 5, 2011 No just replaced the two bearings $20, and put back the worn brushes (did not get a price for the two 5MM by 8MM by ~22MM but was hoping that they be less than the ~$20 brush assembly) after being adviced that they are still good. Neither did I try to polish the 1MM worn in diameter slip ring. Notes: 1. Could not remove the four small interior hex bolts with a phillips screwdriver damage all the slots, used a socket instead maybe ~3.5MM or was that 5MM and the socket is a tight fit with the adjacent structures. 2.When tightening the four bolts holding the alternator assembly together, I may have over torque them and the alternator did not fit the mounting bracket. Then I backed out the bolts 1/2 turn, then it fit over the bracket. 3. If the brushes stick out 1/4 inch out of their housing to contact the slip rings and have good spring force let them be. Quote Link to comment Share on other sites More sharing options...
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