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Old February 26th, 2018, 13:22   #11
Veteran Member
Join Date: Mar 2011
Location: Northern MD
Fuel Economy: Race: 12mpg, Gandma:65mpg

well im not going to go back to the scrap yard where we dumped a cummins internals after the aftermath of a nozzle hole getting deformed and putting a hole though the piston and the sidewall.
Here is a good read and this is exactly what happened to our beloved 5.9 cummins but ours was way worse damage

When a poor spray pattern exist, as described above, the following actions
usually take place:
3.3.1. Washing away of the oil film on the cylinder wall
Whenever a jet of diesel fuel is directed onto the cylinder wall, the thin film of
lubricating oil is washed away. This leads to dry rubbing of the piston and piston
ring on the cylinder wall. Due to the absence of the lubricating film, the friction
coefficient rises and excessive heat is developed. Damage to the surfaces,
leading to eventual seizing of the piston usually results. In some cases
accelerated wear can also take place. In the initial stages of piston failures, the
position where the jet of fuel is directed onto the cylinder wall can clearly be seen
on the piston crown and on the piston side where seizing starts. The damage
usually starts above the top piston rings and then gradually works downwards,
towards the skirt of the piston. The following photograph, Fig 9, shows such a
piston, which is in the initial stages of seizing. "

"Dripping from nozzle
Another possibility is that due to poor closure of the needle on the seat in the
injector, fuel might drip from the injector tip and wet the surface of the piston
crown. This then results in combustion taking place directly on the piston crown.
The protecting stationary gas layer, which normally protects the piston material, is
no longer present and this eventually results in melting of the piston crown, which
is shown in photograph Fig 10 below."

The effect of both these types of failure, is that the needle becomes sticky in his
movement and that bigger droplets are emitted and in some cases jets of fuel are
emitted from the injector tip. This would then result in piston failure and/or bigend
bearing failure.
The effect of the stickiness of the needle is that the seat of the needle gets
damaged and Fig 31 shows such a needle under the microscope, indicating the
rough sealing surface which is no more in a position to seal properly

here is another good read

The DIY for nozzles specifically says "Although this is an easy job, cleanliness is extremely important! The nozzle holes are very small and particles can damage and clog the injectors. While the injector tips withstand thousands of psi of combustion in the engine, having dirt stuck behind the tiny nozzle orifice is like squeezing out an apple sized kidney stone - you're at risk of a blowout."
How am i talking out of my backside when i have had a few engines completly destroid by this, i was on the mechanics side of this build was was on the assembly of the engine, the guy (Francis) who worked for our company did the fuel system and he literally did this job in 30 minutes and did a piss poor job. other than a hole though the piston and the side wall, the nozzle had a hole in it and when we took it apart and scoped it with a microscope, the inside of the seat for the plunger had scaring damage like if a piece of sand or grit was bouncing around and blew out one of the holes causing a strait shot of fuel to melt the engine to death.

Right from kerma, i think they know what there doing!

Last edited by Mongler98; February 26th, 2018 at 13:31.
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