You will not hurt it any more then it is if you run it a couple minutes and see what is happening withe the V. CVR off.
Maybe a simple thing like a rocker jam nut came loose...I do not belive it is a piston..something more simple

 

Roger that. Hope that's all it is.

 

He's got an 1800 Horsepower Cummins Competition Pulling truck, so I'm "hoping" he's a good mechanic!

 

LOL, Don't forget, when there are 2 Barbers in a shop, you always choose the barber with the worst haircut.......... Just be careful man.

 

I think he's the only mechanic in his shop.

 

Here's some Videos of the dude's truck in action!

phdperformance Videos

 

Ok, got it flat-bedded to the shop today. Fired it up (without the valve covers). Mechanic says the valve train appears Ok and not damaged.

It's not giving the "normal" sounds/symptoms of any piston, ring, valve damage. Could be a possible injector or head gasket issue.

He's going to do a Compression test and go from there.

Now here's where it gets weird....

While running it without the valve covers and after running it (while misfiring) for 3-4 minutes, the engine will begin to backfire(?) FROM the crankcase and back thru the valve guides causing ALL the smoke.

Kinda stumped at this point as to WHY there is pressure being built up inside the crankcase. ???

The Oil pressure is fine, NO bubbles in the Coolant, Oil not milky....

Anyone ever heard/seen this happen on a Cummins ????

I forgot the Memory card for my camera so I only have this short Video Clip...

http://www.youtube.com/watch?v=1cFmfrpJKwY

 

My bet is when he pulls the injectors for the compression test he's going to find an injector missing it's tip that's pumping gobs of fuel into one cylinder.

 

yup, me too, bet or loose valve train thingy

 

He did mention that as a possibility.

Just waiting to hear back from him at this point.

 

Still waiting to hear back from my mechanic....

 

Mechanic just called and said it's a blown head gasket around hole #5.

He swapped in a different set of injectors and the symptoms stayed the same. He said the compression was down on #5, but not real bad. He also could feel where the air was blowing from where the gasket had blown.

Going to get the head decked and valves checked over before reinstalling it.

I dodged a bullet on this one! I was prepared for the worst!

 

he swapped the injectors first, before he noticed air blowin out the side of the head ??????? dayum, I sure hope ya got upgrades in there and not just stockers that you obviously did not need !

 

He guessed wrong, sorry
I will go out on the limb here...
That was a short clip you posted, the noise was intermittent.
IF it was a head GSKT. I would think it would be a bang @ every comp stroke as it would not very......
Your noise was slower then crank speed by 1/2 (or every other time ), that leads me to believe valve train something or other ..or a miss firing inj.
I like it out here on the limb, its a bit lonely...but I get it right most the time

 

Could be injector, crack line one at a time to find dead cylinder. Did you just change injection pump timing recently? gear could have slipped on pump. Is it blowing white smoke? Pull cover and check valve clearances and pushrods make sure they are all OK.