I have an 83 240d with no compression in the #3 cylinder. I've tried marvel mystery oil and brake fluid. but no luck.

When I remove the injector and squirt some oil into the cylinder, the compression jumps to 380. This tells me it's not a stuck valve or something in the top end.

Is this a correct assumption?

I ran the engine until it warmed up, removed the air cleaner and sprayed some water mist into the intake. I read a few post about water injection and wanted to see if this would help with the compression.

Would it make sense to remove the intake and spray the mist directly into the #3 intake so I target the cylinder with no compression?

Has anyone done this?

I'd rather not do a complete rebuild but may have to if I can't get compression in the #3 cylinder.

Thanks for any advice/input.

Pete