no power..Cummins 444E in school bus

I am assuming they have tried new filters?

 

Long shot. The 444E has varible timing controlled by a value that the oil pressure makes it work. Sometimes the value gets plugged up w/ dirty oil,ect. This will cause a loss of power. Good luck folks.

 

Keep running the diesel for now. There really isn't much they can do. Low voltage will cause low power. Have them check the air filter. Have them check the oil level and coolant level. Are they getting a "Check engine" or WARN engine light? If no warning lights I would say they have a fuel problem. Hopefully it clears up!

 

Ok, if no check engine lights, that means that the high oil pressure injection control system is ok, very important and a common cause of low power. Engine coolant temp is ok, base engine oil pressure is ok. The low power may be also caused from low turbo boost. 444's don't generate too much, but have them check all the flex hoses between the engine and air to air cooler mounted in front of the rad. Also at the turbo charger and the "Y" section to the left and right cylinder heads.
How are they making out now?

 

I am going to say it is a fuel system problem. If that stuff gets to thick and gets into the fuel system it will take a while to work it out. If it was a High Pressure Oil problem then my guess would be a sensor like the IPR in the High Pressure Oil Pump. I am still going to say it is on the fuel side though. The 7.3 liter can run no problem on that stuff but as soon as it starts getting to thick it can make the motor run like crap and can also do injector damage