Troubleshooting help

[Rawze]

(05-15-2019 )Jrloar Wrote:  I have an ISX CM870 in a 2007 9400i. My problem is a leaky injector (I think) to the point that the engine will hydro lock after sitting overnight. I am assuming it’s fuel because after it does start it misses for a Minuit or two before it smooths out. However I have a different issue that may be the same issue. After it warms up the coolant tank will build pressure constantly while running verified by hand on the cap hole only. I’m going to stick a pressure tester on it today and see exactly what kind of pressure it builds. I am also getting a small amount of moisture in my oil verified by milky oil in the filler neck, and when warmed up what appears to be steam out of the filler neck. I’m sure it needs an injector because it has had a slight idle miss for about a year now.
I did have it pretty hot one time when I blew the radiator hose on a bridge and drove it to a safe spot. Non emission compliant truck so no cooler to leak and has a new oil cooler on it from about six months ago.

Could the moisture in the oil be coming from an injector cup? Could the pressure in the cooling system also be coming from an injector cup? If so is there a way to replace the cups without pulling the head?

most of your description would point to a head gasket+liner issue.

remove the oil and drop the oil pan and let it sit over night with 20 psi on the coolant system,.. look for coolant seeping out of the bottom of the cylinder liners next day while turning engine by hand slowly. Find out what cylinder it is.

Cummins injector cups are not meant to be replaceable. By the time you get a leaky cup, the rest of the head is almost always slap worn out any ways. - trying to fix injector cup is a stop-gap measure at best.