while they can fail due to dry rot(small cracks),
the 2 biggest reasons for failure are oil leaks breaking
down the rubber, and stupid people smacking them on
with a hammer......this is true for ANY engine, not just
the 6.5 as SOME people would lead you to believe.
TomEdited by: RATDOC
I had one trash out at 85,000 miles..It caused a massive ticking sound, like bearings in a compressor or alternator going. I couldnt figure it out....till I read bout it somewheres. Mine trashed out early probabaly because our PTO setups run off that pulley, and add alot of force on the crank pulley. When I undid the PTO belts the pulley pretty much seperated...It was like 80 bucks for a new one from GM..I have heard alot of these failing myself......If I didnt have the PTO belts holding the pulley on...she would have gone right through the radiator. Bill
I had my crankshaft break at 112,000 miles, and the probable cause was the balancer. The rubber had moved and squeezed out between the two pieces which may have produced enough vibration to cause the crank to snap, some others have had the same issue and it seems that at about 100,000 miles may be the life of the rubber that goes bad. Check yours all around on both the front and back, if its comming out I would replace it.
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