N14 dropped valve or cracked piston

When you lose a piston and it really builds a lot of crankcase pressure, the oil will be forced out around the accessory drive seal as well as the front crank seal….. I promise!!

Drove in from Louisville with oil dripping off the neck of my lowboy….,

 

The older engines like mine don’t tolerate being lugged, many make that mistake with the old mechanical Cummins.

It will crack the wrist pin bore, and the crack will continue over time right up to the top of the piston.

Guess what happens then…? Piston is removed looking like you took a torch and cut down through the whole side of it, rings and all….,

 

If the crank case pressure is too high the turbo will pass lots of oil out both sides because the sealing rings count on having more pressure on the outside than the oiled area.
I would think that to suddenly produce that much crankcase pressure especially at idle it would have had to have a valve completely gone allowing cylinder pressure to come back into the top though the guide. I would suspect that if it ate a valve that bad you would see damage on the exhaust side of the turbo. I also can’t believe that even if all 3 rings had broken that it would allow that much blowby especially at idle. Pull the valve covers first to see if there’s a missing valve, usually a broken piston in a cool engine will tend to send the most gasses up though the rocker box it’s below. Might save some disassembly time.

 

I promise it will have a lot of blow by even at idle if it’s a bad piston….

 

You’re probably correct that a piston broke. based on his comment about having an ecm he almost certainly has steel top pistons with aluminum skirts. They tend to just split down one side of the steel top instead of breaking up like yours. it will still let enough by to cause his problems…that’s a good one you got in the picture though, maybe one of the best I’ve seen.

 

Started sounding like the little man with a big hammer about 80 miles from home. Ring worked its way up got embedded in the top of the piston from being smashed against the head.

I was fortunate it never touched the injector, did leave some marks on a valve along with taking the edge of one valve off.

You mentioned steel top piston, I drug a truck in from S Carolina with my 5th wheel wrecker few years ago. It had a N14 with steel tops and making a chattering noise.

Steel top actually broke loose from the wrist pin on it….

 

lets just hope it looks better than this…

 

That's a lot of damage.

 

Every time i’ve known an engine to drop a valve it gets munched up and blown thru the turbo causing it to be scrap. I’d suspect if no loss of power the turbo oil return drain is plugged. This will cause the turbo to put oil in both the intake and exhaust. Worse case could be a spun bearing or broken piston. Both have been known happen with no loss of oil psi and very little loss of power sometimes.