7700 dead cylinder 4

[JAC FARMING]

Working on a 7700 thats been sitting quite a while. It runs on the first 3 cylinders but not the last. Motor was locked up due to water in last cylinder and i dumped pb blaster in the wholes and worked it over with a bar for a couple days and got it running. The injection pump is doing what its supposed to. If i crack all the injector lines it dies down except on 4. But it does shoot fuel out. I switched the injectors around and that didn’t work. Pulled valve cover and it was kind of rusty on top of cylinder 4 but the valves are doing what there supposed to as well. I filled up coolant and oil isn’t milky and coolant doesn’t have oil in it at least at the moment. And it does have compression. How much i have no idea i cant get the compression tester to hold it just blows the cork gasket out everytime. So ideas on what could be wrong. It starts ok kinda but it revs up kind of slow because of the dead cylinder. But for only 3 cylinders it seems to run smooth.

 

[Destroked 450]

Blows the cork gasket out ???
The cork seal is only there to keep trash from getting between the injector and the head, it does nothing to seal the injector
The injector seals at the bottom of the injector bore with a copper washer, if you haven’t cleaned the bottom of the bore a compression adapter won’t seal properly
Since you swapped injectors around and the issue stayed with #4 cylinder I’ll say you either have stuck rings or a valve not seating properly
There is also the possibility of a plunger in the pump not working properly and only delivering a small amount of fuel or not developing enough pressure to pop the injector