Top Stop Injectors Torqued Too Much

[mpuvdd]

Hello all,

I have a Cummins NHC 250 that I recently replaced the top stop injectors on. I went through and set the lash for valves and injectors using the torque method on the injectors. However, as foolish as I could be, I torqued the injectors to 6 ft-lb rather than 6 in-lb as the manual called for and proceeded to try starting the engine. It did not start.

Upon cranking the engine the truck will blow white smoke and I wonder if I may have damaged the injectors or if I still haven't primed the fuel system completely yet. I've read that white smoke can be a case of defective fuel injectors. Is it likely that I have ruined them?

Thanks,

mpuvdd

 

[Julian]

I just completed adjusting my NHC-250 top-stop injectors. There are many versions of the procedure floating around and some are incorrect. It has been said that the TM has an error as well. Search for the thread that Will Wagner wrote about this and understand it. My method was to adjust valves and injector on the same cylinder at the same time, torquing the injectors to 72 inch lbs (6 ft lbs)- when the injector should be fully closed. Worked great and cleared up a lot of excessive smoke.

 

[WillWagner]

Depends on which method you used, inner base, or outer base. Inner base, adjusting A-I3, V5 - B-I6, V3...etc or outer base, adjusting A-1 V&I , B- 5 V&I...etc. If you did 6 in lb on the inner base method, you are good UNLESS the inj springs were weak and the 6 in lb pushed the plunger too deep in the inj body. If you did the 6 FT lb on the inner base method, you just F-ed up a set of injectors and push tubes. Pull the lids and look down the injector push tubes, if they are bent.

inner base method
( Injector lever nose UP)
6 in lb on the inj, .011 intake, .023 exh
A....I-3 V-5
B....I-6 V-3
C....I-2 V-6
A....I-4 V-2
B....I-1 V-4
C....I-5 V-1

Outer Base Method
(Injector Lever Nose pushed DOWN)
inj. 72 IN LB Int .014 Exh .027
A....1-I then V
B....5-I then V
C....3-I then V
A....6-I then V
B....2-I then V
C....4-I then V

Cross heads are a another story. I think I described adjustment in the write up I did. If it isn't a sticky, maybe I will make it one.

 

[WillWagner]

Stickied....see post 8