96 explorer 4.0l quit on highway (repaired)

[somebobby1]

Crankshaft timing gear was sheared on keyway. Not too sure how to explain this but about one inch of the crank gear was sheared because it wasn't fully seated on the key stock and over time, 113,000 miles it wore through.
The crankshaft also has a larger shoulder next to the block with a notch cut in it but no key stock there. it is stepped so it can't really be keyed anyway, but the new crank gear has a little tab on the block side that engages into the cut out to hold it in place. The original was completely flat on the block side. Also when I ordered the timing set, the tensioner for the 96 4.0 had too long of a tensioner arm and it was placed lower on the assembly so it hit right on the crank gear and wouldn't line up with the bolt holes. Ordered the tensioner for 94 and prior 4.0 and it was the right one. go figure? I ordered my parts from sealed power and was not impressed. I've seen stronger gears on a bicycle. cost 54.00 for the 3pc timing set and 50.00 for the tensioner. I saw a set on ebay for 38.00 and it was complete with all parts including the chain guide. Should have bought it but I thought sealed power would be better quality. Replaced some other parts since I was right there and fired her up and I'm back on the road again.

 

[96eb96]

Crankshaft timing gear was sheared on keyway. Not too sure how to explain this but about one inch of the crank gear was sheared because it wasn't fully seated on the key stock and over time, 113,000 miles it wore through.
The crankshaft also has a larger shoulder next to the block with a notch cut in it but no key stock there. it is stepped so it can't really be keyed anyway, but the new crank gear has a little tab on the block side that engages into the cut out to hold it in place. The original was completely flat on the block side. Also when I ordered the timing set, the tensioner for the 96 4.0 had too long of a tensioner arm and it was placed lower on the assembly so it hit right on the crank gear and wouldn't line up with the bolt holes. Ordered the tensioner for 94 and prior 4.0 and it was the right one. go figure? I ordered my parts from sealed power and was not impressed. I've seen stronger gears on a bicycle. cost 54.00 for the 3pc timing set and 50.00 for the tensioner. I saw a set on ebay for 38.00 and it was complete with all parts including the chain guide. Should have bought it but I thought sealed power would be better quality. Replaced some other parts since I was right there and fired her up and I'm back on the road again.

Sounds like a statistical manufacturing error on the original part. These engines aren't known for this issue. Sealed power could very well be the OEM (Federal Mogul). Great that you are on the road again. Good luck!