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[haul_n_horses2]

Originally Posted by deployed2

I have a DT466 7400 SFA 6x2 2007 dump truck that will start fine when cold. It will run all day with no codes. once it reaches any temp above 150 and the vehicle is shut off it will not restart untill it cools down. once cool it can be started and shut off several time no problem. I am in IRAQ and have limited test equipment. My best guess is that the IDM is somehow not responding when hot however, that is just a shot in the dark.(no pun) i have changed several of the sensors with a know good truck too no effect. Any help would be great. thanks!

Thank you for serving your country. How many miles on the engine/injectors?

per Golfer: The poppet valve (in the HEUI injectors) is similar to a valve in a cylinder head, but this particular valve meters the oil going into the injector from the oil pump/heads.

With excessive mileage, this is the area of the inj that needs the most attention.

To confirm the poppet valve as being the problem, you'll need to pull the valvecovers, and remove the top of one (or more) injectors...unclip the harness to an injector, remove the 4 screws (Torx #15), remove the solenoid, remove the aluminum spacer plate.

You will see a 1"x1" square plate (armature plate), with a goofy screw going through it's center (the poppet screw).

This screw holds the armature to the poppet valve.

Take a set of feeler gauges, the thinnest you can find (typically .0015", or one and a half thousanths of an inch), and try to slide the feeler gauge up underneath the armature plate.

If you cannot get .0015" underneath the armature plate, then that plate is "bottoming out" on the inj body, before the poppet valve can "reach" it's valve seat.

If the poppet valve is not reaching it's seat, it is always leaking high pressure oil from the system, preventing sufficient pressure to rise, to fire the injectors.

The injectors will not fire until the computer sees that there is atleast ~600psi in the system...

the reason that the truck will fire when cold is that the thicker oil is effectively "sealing" this leak (to some degree) to allow enough pressure to be built in the system to fire the inj's. When the oil is hot and thin, enough VOLUME of oil is leaking by the poppet seat to prevent sufficient pressure from being built.

Unfortunately this is not something that you can properly repair yourself, as the injs will need to be completely torn down and machined to get the clearances back into spec.

What has really happened to your inj (assuming there is indeed less than .0015 under the armature) is that the poppet valve has beaten itself into the body of the injector..seating lower and lower and lower, until it just ran out of room to go any further...similar to how a valve in a cylinder heads can beat itself down into it's seat...this is just normal wear, one of the few parts of the inj that just "wear out" with high mileage. Golfer