Thought I would pass on these pics to you guys since this type of failure is not too common. Or should I say, the extensive amount of damage that it caused.

This is on an FL70 Freightliner Ambulance with the ISB (53 block). The truck came in smoking white badly. I did an injector cutout test using the laptop and found that #5 would not change the sound. Pulled the injector and did a compression test. Total leakdown in seconds. In fact, it was so bad you could take an air hose and blow through the injector bore and feel the air coming out the bottom of the rod with the oil pan off.

Pretty much what happend is that #5 injector hung wide open and overfueled which either hydraulicly cut or melted the side of the piston. The piston pieces then hung in the intake and exhaust valves and bent them. Luckily, the cylinder walls were not gouged, but the cross hatches were gone. After pulling the head today,, this is what I found.

Pictures can be seen here https://www.dieseltruckresource.com/....php?album=448

 

Shucks. It just needs a new set of rings and slap her on back together.

Ive never heard of an injector hanging open. It would be catastrophic as seen here.

 

Could have been worse
(don't think this picture could be though)

 

Ouch!
With the top/side of the piston in that kind of shape, its surprising to hear there wasnt more cylinder wall damage.

I have pistons off of a NTC 5?? that someone purposely overfueled. The pistons have cracks all over the top.
The leak down went just like you discribed.

(see photo below)

 

This is just one of the pistons that I have in my shop that Im now using as pen holders.


Rich

 

you probly know this but ...make sure your piston cooling jet is still in place as they get broken off real ez

 

Yeah, I made sure the nozzle was okay.

Infidel, I have definately seen worse failures in general than the one I posted. But, I havent seen an injector hang open and cause this in quite some time. The picture you posted, was it an injector failure or just a common overheat failure etc?

 

looks like inj. failure to me ...when you see cutting torch action its timeing or inj.problems..in the end it is sort of the same thing

 

White smoke was the only symptom?

 

Constant white smoke and low power and raw fuel coming out the tailpipe. You could tell that 1 cylinder was not firing. It sounded just like a bad injector on 1 cylinder. Thats why when I did a cylinder cut out test there was no change in the sound on #5. This engine has been a problem child for them. At 160,000 I have put a reman VP44 on, a head gasket, and a lift pump. But, if you take into account on how it is driven and how much it is idled I guess 160k isnt too bad on an ambulance.

 

It was an injector failure, didn't take long to do it's damage either.