well this is a 1st for me i reassembled my intake yesterday got it all buttoned up fired the engine and kaboom sounded like a shotgun goin off .i got out and to my surprise the front pan lip seal was blown out as well as a golf ball sized hole wear the pan was rusted thin and leaking .i checked the plenum with a bore scope and its ok .found #2 and #4 were crossed but i still cant really figure out the cause of the crankcase explosion there was brake clean used on the gasket surfaces before i put the intake on so ok i got fumes but what the hell lit it off .so with drip pan under the motor i started it ,and it still skips on 6 and 8 so probably injectors since i fixed everything else ,pulled the valve covers and all rockers are working properly .next will be a compression test .anyone ever have this happen?

 

i've been to 2 worlds fairs and a goat .. well never mind about that, but i've never heard of a crankcase explosion.

for a temp repair you could rtv a sheet metal patch over it. there's no pressure in there - well at least not in a normal one. LOL.

 

does it still run? knocks? did the crank maybe break?

or was it just a matter of a weak oil pan?

 

Beats all I ever helt, felt or smelt!

 

No parts laying on the ground? No crater in the ground? LOL

Dude... Wow.
At first I was thinking you launched a rod, but I would hope you would see that flying through the air...

I think at this point, you need to pull whats left of the pan off and inspect to see what all is missing...

 

Did you hook the ground strap back up to the starter properly?

I imagine that could arc strong enough to ignite oil/gas vapor in the crankcase.

 

?? this is something i wont forget, i never thought about that.

 

That's just a theory, but he stated it happened when he cranked it over, and there's a hellva lot of juice going thru the starter on crank.

 

ya im gonna pull the pan .i used a lot of cleaner when prepping the all the surfaces so im sure i had puddle in the oil pan .the only thing i can figure is i had some blow by on the crossed cylinder that ignited the fumes .engine is intact just blew out the lip seal and the rusted out portion of the pan .i think my wife probably pissed herself as she was standing directly in front of the truck when it happened .inspected the intake plenum with a video bore scope and the pan is still there and tight so it was in the crank case not the intake, maybe the backfire from the crossed cylinders flamed a vacuum line and ignited it i dont know its never happened before ive been turning wrenches for 20+ years and have never seen this happen .ill take a picture later today

 

I hate to state the obvious and it's too late anyway, but why would you try starting it without changing the oil first? Seeing how you knew you were cleaning and getting solvents and debris down there. I'm not being a dick, LOL Just curious. Look on the bright side, you got to scare the crap out of the wife, I bet the look on her face was priceless