while tring to tune my fuel pressure, pretty sure cracked a piston

78f100 · May 30, 2012

Well guys my truck has been doing great since the build but having some trouble maintaining rail pressure. So today I was tuning on the airdog reg and test driving it, I tured the pressure on the airdog down a little and stood in it from about 60mph it held rp of 21k up from 18k, pulled like a freight train and then sounded like a monkey with a hammer under the hood. Boost hit 52psi and egts were good when the knocking started. It had greyish smoke rolling out so I towed it home put the ae on it no codes and all the tests on the ae pass. Ccv tube has quite a bit of pressure coming out, pretty sure cracked piston, what yall think? It didn't puke any coolant.
I wonder if they were already weak from when my egts got really high and the hg let go. When I did the studs all the pistons looked good idk, Im gonna do a compression test tomorrow, and gonna try to upload a vid of what it sounds like.

mortal798 · May 30, 2012

Compression will tell... do you have a cylinder leakage tester?

78f100 · May 30, 2012

just a regular diesel compression tester.

78f100 · May 30, 2012

This is a bad video I have a tractor in the shop right now so no lights, but you can hear the knock.
http://www.youtube.com/watch?v=GXmw7eW0g1o&feature=youtu.be

White_monster · May 30, 2012

Sorry to hear bro. Any questions feel free to ask. Keep us informed of what you find.

Dzchey21 · May 30, 2012

Pull that valve cover off and make sure it didn't break a rocker or something stupid like that first.

Sorry to hear about your luck

Heavyhaul · May 30, 2012

Sorry to hear that. Hopefully worst case scenario you can just throw a piston back in it.

powerlifter405 · May 30, 2012

Dzchey21 said:
Pull that valve cover off and make sure it didn't break a rocker or something stupid like that first.

Sorry to hear about your luck

:whs:
Check the "cheap" and simple stuff 1st. You may have lucked out and did just as dustin was saying vs toasting a whole cylinder or even worse.
good luck

faster6.0 · May 30, 2012

Prayers sent

Jbone@MPD · May 30, 2012

For sure check all the rocker arms. A broken one will make a horrible sound

Craig@MFI · May 30, 2012

Sounds like you have cracked a piston if a rocker arm broke off it wouldnt have extreme ccv or smoke grey
let us know if we can help you with anything

Dzchey21 · May 30, 2012

I've seen stuff smoke Grey from a broken rocker on the intake valve and when the piston goes down and the intake valve should be open and its not it will pull oil past the rings in some cases. The crankcase pressure however wouldn't come from that. I'm hoping for the best for you.

How much pressure does the ccv have? Usually a broken piston will cause a pressure surge in the crankcase. you can usually feel when that cylinder hits is when the crankcase pressure goes up.