I had air in my system, so to get rid of it, I cracked open the top nut on the injectors to purge the air out after fixing the air leak. No problem there, but now some of them leak. I tried it again, gave the top nut a good crank, but careful not to overtighten it and they still leak. I went to the Cummins dealer and got a exploded picture of the injector. It shows that there are rubber seals under the top nut. I guess that I tore them when I turned the nut. If I completely remove the top nut, will I gain access to the seal? Will the fuel line come off so I can get the seal on? I am concerned about the high pressures in there, can I bleed it off? Thanks in advance.

 

I just did the injectors on my 95 this weekend and didnt notice a seal under the top nut. Mine had a bevel on the fuel line that sat in the top of the injector. Preasure from the top fuel line retaining nut kept it from leaking. I think that some dirt got in between the injector body and the retaining nut causing a leak. The local injection shop gave me the needed replacement gaskets and they were the copper crush gasket for the injector to head, fuel return line copper crush gaskets, and rubber Orings that go in the top of the injector hold down nut to keep trash from getting down in the injectors seat area. Nothing for the top fuel line retainer nut.

 

The rubber o ring is only a seal to keep the threads clean on the hold down nut. The hold down nut is what's sealing your injector. Try tightening that up, I've never had any issues with the fitting leaking between the line and the injector.

 

don't be afraid to tighten your injectors it;s better to get it the first time than to tear it all back down again and do it again