my 2002 blazer, 4wd, 4.3L was running just fine, my wife was about 5 miles from home check gages light starts flashing, and the oil pressure dropped to zero. About 1 mile later she said she heard an explosion and the truck stalled.
Then saw smoke coming from under the hood. Checking it out, I am assuming the oil pump has died but noticed the valve cover gaskets on both sides had blown out of the covers. I'm not sure if I can tackle the oil pump in the garage so, while replacing the gaskets, I noticed a hole about 3 inches long and 1.5 inches wide in the timing chain cover. and there is a crack around the edge of the cover for about 3 or 4 inches each side of the hole. The cover broke in the outward direction, so something didn't go into the cover, something was trying to get out.
Neither of these thing make any sence to me, never seen velve cover gaskets blow out or had a timing chain cover break.

Any help or ideas here would be great
Thanks

by the way, the truck does still start

 

Doesnt sound good at all.
sounds like something in the block jammed up when the oil ran out and blew the chain out...valve covers sounds like a outward pressure...explosion in there.
i am no expert but....damn!!

 

Very rare for fuel-air in the engine to reach the right mixture but that's what did that.. question is what kicked it off.

 

does not sound good al all but can you get pictures ot the timing cover ?

 

my first thought... she drove it with no oil pressure?

 

Yeah.. the engine's probably trash unless it had a good synth* in it. But OTOH if it starts then it wasnt the timing chain.

I would love to see that engine torn down. I'm thinking small fpr leak and maybe a stuck pcv.
USUALLY the crankcase atmosphere has too much fuel/oil to ignite. Like putting a spark plug in a gas tank, nothing would happen. But where did the 'spark' come from.
alternative theory. ... a holed piston.

*Smoky Yunick once drove a Chevy Small Block for an hour with no oil after it was conditioned with Amsoil or some other synth he was shilling

 

Among other finds, I'm voting for a stuck piston and plugged PCV system.

 

Scared you are going to get more questions on this then answers. You say it still starts, then what?