QuestionI AM GETTING A HUMMING SOUND FROM THE REAR, ONLY WHEN I LET OFF ON THE ACCELERATOR AND AT LOW SPEEDS. I'VE TAKEN THE FILLER PLUG OFF TO CHECK THE OIL. WITH MY FINGER I REMOVED SOME OIL, IT SEEMED TO BE THICK LIKE HONEY, VERY DARK AND SMELLED BURNT. I DID NOT SEE ANY METAL FILLINGS IN THE OIL. SHOULD I PUMP THE OIL OUT AND ADD NEW OIL? SHOULD I GET IT CHECKED OUT INSTEAD? DO I CONTINUE TO DRIVE IT UNTIL IT BREAKS DOWN OR WILL IT COST LESS TO REPAIR IF CHECKED ASAP. HOW DIFFICULT IS IT TO REMOVE THE REAR END TO GET REBUILD, IS IT SOMETHING I CAN DO. WHAT SHOULD I DO! THANKS FOR THE HELP
AnswerThe grease is supposed to be very thick and it does stink to high heaven - I'm guessing that is all normal. The level should be just below the bottom of the side plug hole - I usually stick a small screwdriver into the hole at a downward angle, and if I hit grease within a 1/4 inch or so, I know it's fine.
Your noise is almost certainly a worn pinion bearing - which is not that hard to fix, and you don't have to remove the rear end to do that. You will need to disconnect the driveshaft, and remove the coupling that connects it to the rear end. The big nut in the middle of the coupling is VERY tight, and you may not have a big enough wrench to get it out, but once it is out, the coupling slides out, then the oil seal behind it comes out with a seal puller, and finally, the pinion bearing is behind that. It really requires someone with experience to set the new bearing at the right distance in, so I suggest you find someone who does differential repair and let them take care of it, but it should not involve anything like a complete rear end rebuild.
You can drive it the way it is, just keep an eye on the rear end grease. As the pinion bearing continues to wear, it will begin slinging grease out the front seal of the differential, which stinks and makes a mess on the underside of the car, but it really doesn't hurt anything.
Good luck,
Dick
