• Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

Another cummins nt855-c250 engine need help!!!

mechanic3

Member
Joined
May 26, 2013
Messages
13
Location
Fiji
Occupation
Mechanic
Sorry guys but i have another engine here that i need help with adjusting its injection timing.
If anyone out there can help me ?
Here are some information about the engine :

CPL#: 026
Family Code: 091
Engine# : 23135440
Model: NT855-C250
Content# : D091075CX01
S.O# : 9517
Date Of Manufacture : 1977
 

repowerguy

Senior Member
Joined
Mar 18, 2015
Messages
810
Location
United States southern Ohio
Occupation
mixer truck mechanic
With the valves on cyl 5 loose and pulley on A adj. 3 inj. to 5in. lbs. then on to B and 6 inj. and C and 2 inj. and A and 4 inj. and B and 1 inj. and C and 5 inj. This is for top stop inj. on big cam motors. 5 in.lbs. = about all a normal man can turn with his thumb and index finger on a screwdriver handle. I have done this when I don't have my torque wrench available. Set the valves at .012 int. and .025 ex.
 

mechanic3

Member
Joined
May 26, 2013
Messages
13
Location
Fiji
Occupation
Mechanic
Thanks repowerguy I have tried that but i couldnt get the engine fired up.
I got two engines and i swapped the camshaft. They are both NT855 . The first engine number is 23104864 and S.O number is 7487 and it was manufactured in 1972.
My second engine is the one with the above information (My Thread) . Can there be any other method or change in the adjustment?? Because i swapped the camshaft.from the 1st engine to the 2nd engine. Does the engine numbers have something to do with this because of the date of manufacture???
 

shopguy

Senior Member
Joined
Jul 2, 2011
Messages
504
Location
Alabama
Good instruction repower but sounds like a small cam non topstop engine,if so turn to A or 1-6 vs find loose valves on 1 or 6 set the valves and injector on the same cyl then turn to the next mark and set the valves and injectoron the next cyl in the firing order and so on set injectors to 72 in lbs F.O 153624 (do not confuse or combind these two methods)
 
Last edited:

kshansen

Senior Member
Joined
Mar 11, 2012
Messages
11,179
Location
Central New York, USA
Occupation
Retired Mechanic in Stone Quarry
Thanks repowerguy I have tried that but i couldnt get the engine fired up.
I got two engines and i swapped the camshaft. They are both NT855 . The first engine number is 23104864 and S.O number is 7487 and it was manufactured in 1972.
My second engine is the one with the above information (My Thread) . Can there be any other method or change in the adjustment?? Because i swapped the camshaft.from the 1st engine to the 2nd engine. Does the engine numbers have something to do with this because of the date of manufacture???

If you swapped the cam shafts did you get "ALL" the timing marks lined up right? besides the marks for the crank gear to cam gear there are also marks on the cam gear that need to be lined up with the air compressor/fuel pump drive gear. If these are not lined up at assembly you will not be able to use the marks on the pulley VS 1-6 and so on Or the A,B,C marks depending on the age of engine. There are three different methods to set valves and injectors on these engines depending on type of injectors and what tools you have to work with. Top stop injectors are set to the very light torque as someone already noted, then there is the original method where they are torqued to the 72 inch pounds like another said an then there is the Injector travel method where a dial indicator is used. So I guess we need to know for sure what type injectors you have and what tooling you have to work with.

A couple more things. What was the reason you switched cams, are they the same part number?

You started by asking about injector timing but to be precise that is "NOT" done with the rocker arm settings, this is not a Detroit, it is adjusted by the shim gaskets under the cam follower housings. To do that you need a special tool arrangement that includes two dial indicators, one for injector follower and one for piston travel and the proper instructions that I would not want to try to explain by posting here.Maybe someone who does it daily can but it's been years since I did that job!

And last but probably should have been first if engine won't start are you sure the problem isn't in the fuel supply to the fuel pump or some thing simple like a broken wire to the fuel solenoid?
 

mechanic3

Member
Joined
May 26, 2013
Messages
13
Location
Fiji
Occupation
Mechanic
Thank you shopguy and ofcourse repowerguy for your help. I will try that on monday morning as it is saturday night here in Fiji. And if it does not work , i hope i'll get help again from you two.

Thanks :D
 

mechanic3

Member
Joined
May 26, 2013
Messages
13
Location
Fiji
Occupation
Mechanic
Thanks kshansen :) for that advice. I have checked fuel line and fuel solenoid but there wasn't any problem. BUT i will have to check the the marks on the cam gear that needs to be lined up with the air compressor/fuel pump drive gear, as you have mentioned. Thank you again.

The only reason why i changed the cams was because the original cam was a little bit damaged (on the knob). That was the reason and i thought , since they were both NT855, why not :/

And my apologies for the mispronounciation, should have been injector setting :)

Thanks Again
 

D6c10K

Senior Member
Joined
Apr 1, 2008
Messages
681
Location
Iowa, USA
I scanned the pages from my M931 manuals on injector adjustment. Not sure if the file will attach but I'll give it a try.
 

Attachments

  • 250 Cummins.pdf
    6.7 MB · Views: 466

D6c10K

Senior Member
Joined
Apr 1, 2008
Messages
681
Location
Iowa, USA
Here's some info on the camshaft too.....Hopefully the info is for the engine you have.
 

Attachments

  • Camshaft.pdf
    2.6 MB · Views: 60

DoyleX

Senior Member
Joined
Feb 2, 2013
Messages
572
Location
Minnesota
Occupation
Lever Puller, Gear Jammer, Pipe Twister
I just ran the esn# through my quickserv acct. Same part camshaft 129860. ESN last 440 was set at 250hp. 856 at 280hp.
 

mechanic3

Member
Joined
May 26, 2013
Messages
13
Location
Fiji
Occupation
Mechanic
I just want to take this time to thank all of you for your help :) I have finally gotten the engine to work since last week and have not had the time to come online all of you.

Again, Thank you so much!! I really appreciate it. God Bless all of you !!
 

kshansen

Senior Member
Joined
Mar 11, 2012
Messages
11,179
Location
Central New York, USA
Occupation
Retired Mechanic in Stone Quarry
I just want to take this time to thank all of you for your help :) I have finally gotten the engine to work since last week and have not had the time to come online all of you.

Again, Thank you so much!! I really appreciate it. God Bless all of you !!

So don't keep us in suspense what was done to get it running? The person who had the best information gets a weeks stay in Fiji next winter Right?:D
 

mechanic3

Member
Joined
May 26, 2013
Messages
13
Location
Fiji
Occupation
Mechanic
So don't keep us in suspense what was done to get it running? The person who had the best information gets a weeks stay in Fiji next winter Right?:D

Well again thank you for all of your help. Everyone of you. Well what i did was i used the dial indicator method ; injector3 valve5 etc. :) BUT i followed all the PRECIOUS PRECIOUS advice that i was given. So you know what that means :) everybody hop on the next plane that leaves for Fiji :D . LOL

All in all , it was really a great opportunity to have had help from all of you, experienced people.

Vinaka Vakalevu (Thank you very much)
 

D6c10K

Senior Member
Joined
Apr 1, 2008
Messages
681
Location
Iowa, USA
We'll be waiting for the plane tickets to arrive in the mail. ;)

Glad we could be of help....that's what the forum is for.
 
Top