CM2350 derate 6255 only no fault codes

[Rawze]

(11-09-2023 )greg1227 Wrote:  we pulled truck out to work on some others to get them out. We just pulled it back in and customer read somewhere to look at intake , we removed the intake manifold and it is all carbond up. I know some carbon is normal but how much ? We also ran truck for a couple minutes with intake off heard a definite popping sound and it got quieter when doing a cylinder cut out test shutting off 6 . My questions now how much is normal carbon build up ? Where is all of the carbon coming from ( egr cooler leak, valve seals, rings) customer said it does not use oil or coolant abnormally .

Years of severe neglect, as no one ever doing proper EGR tune-ups on it each year to keep it all at bay. The rest of the EGR system is just as bad then too.

BTW: ANY coolant loss over time at all is too much.
TO check the EGR cooler ... pressurize the coolant system to 20-psi and let it sit over night with the back side of EGR cooler pipe removed, and see if coolant is pooling up in it.

Also read my post above about the exhaust gas pressure sensor and its piping/feed circuit.