4-wheel drive noise [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: 4-wheel drive noise

03-01-2010, 04:55 PM
My 2006 TB with the 4.2L and automatic tranny, with 37K miles. Has developed a noise almost a whine when I put it in four wheel drive. the noise increases as you speed up. Goes away when taken out of 4-wheel drive. Sounds like a bearing thats dry. So a little history. I just had this into the dealership 2-3 weeks back for a grocery list of work before my warranty ran out. One of the warranty jobs was the front differental was leaking. They replaced the front seal and cover gasket. I put the TB up on my lift this weakend and inspected things. First of all no more leak. I opened the differential filler plug to see if they refilled it. It's full infact a bit of oil ran out the fill plug hole. I noticed the gear lube that was on my finger was dirty black, and has microscopic pieces of metal in it. The gear oil as per my owners manual should be 75W-90 synthetic. The oil has the awful smell that the petroleum based gear oils have. Finally a question. Does synthetic oils have that smell? And there are only a few hundred miles on this oil in the front differental should it be so dirty and have these fine metal particials? If they put in the wrong gear oil could that cause a problem in the differental?



03-01-2010, 10:24 PM
It should definatley not be black, nor have metal shavings in it. It should be golden and clean, however, the amsoil severe gear synthetic I use has an awful smell too.