Brand new premium AAA battery installed a month ago and the car is completely dead after key turned off. Had vehicle checked at O'reilleys and the alternator both diodes is bad, Also, vehicle is humming/whirling from rear differential area almost sounds like cupped tires or bearings but after several inspections have found it hard to pinpoint the increasingly louder sounds that come from the rear end of truck. Need to find an honest trustworthy mechanic that is able to help me make a decision wether to invest more money in vehicle or get rid of it. It has been extremely reliable and still runs strong at 260,000 miles! Your time and efforts are greatly appreciated!
My car has 260000 miles.
My car has an automatic transmission.
If the charging system was tested and the alternator is not charging and has bad diodes then it should be replaced or have it checked by a mechanic like one from YourMechanic. This way you would have a parts and labor warranty since the diagnosis was done by a qualified mechanic and not a parts store. The parts store may have made a correct diagnosis but there may be other problems in the system that caused the alternator to go bad and a complete diagnosis after the new alternator is installed should be done. The rear end noise may be outer axle bearings or the carrier bearings and would need to be inspected. The most common cause of noise is the pinion shaft bearing is bad. Either way the differential will need to be overhauled.
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