How to leak test a D2 engine

Did you think to listen in the crank case with the exhaust closed and the intake open? If no greater flow through the bad cylinder than the others, you can move on to fuel injection.

Classic way to diagnose is to swap injector from bad cylinder to another one and vice versa. See if the miss moves with the injector or stays with the cylinder (and the injection pump). If it moves, replace the bad injector or probably just put a set in it. If the miss stays with the cylinder, inspect the pump. Look inside the pump housing to make sure the camshaft lobe under that one is not damaged, the lifter yoke is not broken and the plunger is actually moving up and down keeping the lifter on the cam lobe at all times.

In general, if a plunger is stuck up in the pump, it will also lock the rack so where ever the rack was is how much fuel it will get if it starts .............can get exciting😆 Spray stuck plungers with penetrating oil and work the lifter up and down as much as you can. Try not to put a lot of force on the rack, the gear sector on each plunger can be moved and ruin the calibration of that pump/plunger assembly. If all the plungers move up and down as you rotate the engine, then if the rack doesn' t move easily back and forth, you should be safe to work it back and forth with a bar or something as you spray the slides where it moves through the housing.

Thanks cc,
I think the ring leakage is about the same all the way across. I've been through my injection pump and everything looks good there. Fuel comes out the line on number 2 but my engine has a distinct miss, is hard to start, seems low on power, and smokes white. The only thing remaining now is the injectors. Do they fail often? Do they carbon up? Do they cause symptoms like mine? I guess I just need to pull them out and learn. I really thought I had a bad valve by the way it sounds, but they seem to seal well. I ve got 40 years experience with small gas engines, but this is my first Diesel. I,m having fun but need to get this thing figured out.

Injectors do get 'weak' over time and sometimes flat out quit spraying and go to streaming fuel.

If you want to see for yourself, you can either take them to a shop with a tester and have them checked and perhaps the hole cleaned out with a tiny drill bit to see if carbon buildup is the problem or just replace once you know that's the trouble.

To test yourself, you can remove the injectors and fuel lines to them. Carefully clean around the connections before hand and keep them clean when you have them off. Reinstall the lines routed out over the track and angled forward toward the radiator some and screw the injectors onto the lines. NOTE! The capsule type injector "valve" as CAT calls it screws onto the adapter or body of assembly only finger tight! It has a loose coarse thread to allow fuel to pass through into the valve from the adapter piece. If everything is clean, finger tight is enough to test them.

Once you get them mounted all on the lines, start the pony motor or turn the engine over with the starter, throttle open and watch the spray pattern. Again, if you have one streaming or doing something abnormal, swap it with another one that's spraying a nice even fine spray. Keep hands away from the spray! Diesel or hydraulic oil injected under the skin a medical emergency. Proper treatment is required or gangrene may set in! Be careful.

Hold down nuts are torqued to 100 foot pounds and there are some o-rings and seals that keep dust and debris out of the space around the injector that you should replace when you do the final install. Fuel injection lines don't normally need to be more than good snug tight. If you have one leak, then tighten some more, but usually a leaker means you have a damaged ferrule on the end of a line. About your only choice is to replace the line. I have never had any luck repairing one that leaked even when tight.

Ok, that's what, I,ll do. Good advice! I think I,ll have to wait until spring, I,ts getting cold and will be snowing soon here in Wisconsin. This will be bugging me all winter.
We do have an injection shop here in Wausau that specializes in automotive and industrial Diesel injection so I could take them there for expert advice.
Thanks.
Merry Christmas