Well got our MBN apart again because it had excessive blowby/dead #4 cylinder. This engine was just rebuilt with after market cylinder kits and all 6 holes were counterbored. Exact same Look to the piston and liner that trevor had in his thread http://www.thetruckersreport.com/tr...-eighteen-wheelers/216652-engine-failure.html but the difference is he had multiple cylinder that were scored in a Acert and we only have one cylinder scored on a MBN.
Not sure if this colouration is the heat marks that Mr.Haney was referring to in trevor's thread, although it is obvious heat issue that scored the cylinder I have no idea why. All 5 other holes look great and the top of the piston in the scored cylinder looks fine as well so I don't think its a bad injector.
My first thought after pulling the piston out was that it was a plugged/broken/bent piston cooling nozzle. To the left is a brand new updated nozzle and the right is the nozzle from #4. The old nozzle as no obvious issues I can find at all, both tubes are flowing and not blocked and the curves on the tubes seem consistently the same with the new one. Not to mention for 1 brand new piston cooling nozzle it cost $100 without the bolt!
Another view of the nozzles old to right right and new to the left
What do you guys think? When rebuilt it was done with IPD cylinder packs, pistons, rings, and liners, and IPD gaskets. Injectors are stock MBN 10R1000's and its running a 550hp 6NZ file, also has a brand new stg 1 Cat turbo put on at the time of rebuild less than 20,000 miles ago.
Single Scored Liner - MBN Cat
Discussion in 'Trucks [ Eighteen Wheelers ]' started by underpsi, Jun 28, 2013.
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Bad injector. ####... I said it!
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By the picture, Old nozzle looks bent, short tube is bent up.
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That hurts!!
How does the #4 nozzle alignment compare to the other 5?
Billh50 Thanks this. -
Most likely an overfueling injector creating excessive heat
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When I'm referring to the underside of a piston..........that is exactly what I mean. Look at the underside of the firebowl. If it is black and blue, with a build up of burn oil right under the firebowl, then it is being over fueled. The sidewall of the cylinder wall and the piston, will naturally show the signs of heat where the scoring took place on the back side. If the underside of the firebowl doesn't show signs of heat, then it turns into a mechanical problem more with the jets, cylinder wall being out of round or lack of piston to bore clearances. You can also have issues with coolant flow blockages in the cylinder block that is causing a cylinder to run hot................like someone leaving a rag in the block has been know to score a few cylinders. -
I didn't even bother to take a picture of the top of the piston because it looks the same as the other 5 pistons. No obvious signs of overfueling. -
sorry to see that, good luck gettin back up & runnin
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I think that blue in the underside pic is exactly what Kurt was talking about...
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