I have a 1989 s10 with the 2.8 and 5speed today driving as usual doing about 35mph it popped almost like a backfire then started jerking then another loud pop and it shut off and wouldn't crank again won't even try. Smells like oil but not leaking. I think a valve might have gone through a piston but I'm not sure any ideads?

 

it sounds blown maby the timing chain couldnt say for sure what with out a tear down though

 

Diffentely sounds like an internal problem for sure.It maybe a spun cam bearing.It`s hard to say since you never stated whether you have any type of hole in your block or not.Or it maybe a crankshaft bearing failure or timing chain failure.

 

the backfire would probably indicate timing or lean fuel. No fuel wouldn't keep it from cranking, so I would say timing. if a valve is open when piston reaches top dead center, the engine can no longer turn over.