NHC 250 Injector and Valve Adjustment Issues

[Kalashnikov]

Now here's the deal: I've got an M818 that was running poorly, smoke, fuel in coolant, no power at all. So, I pulled the injectors and cylinder #2 had no tip left. I figured they are cheap enough I'll replace them all. After swapping the new ones in the truck ran poorly, smoked a TON, and had no power re:25mph on flats. So I looked through the TMs and found the adjustment procedure, picked up an inch pound torque wrench and proceeded to adjust the top end.
I first adjust the injectors but the crank got very hard to turn so I started over; adjusted 4 of the cylinders, 3, 6, 2, 4 as per the TM. Then it got hard to turn and I couldn't align the marks on the accessory drive pulley. So I went back and reread the TM and realized I need to do the valves before going onto the next cylinder. I went thru the cylinders aligning the marks on the acc. drive per each cylinder and adjust the exhuast and intake valves.
First major issue: The exhaust valve and spring on cylinder #2 toward the exhuast side is sticking way up. The rocker touches the crosshead (bridge) even with the adjustment screw way out.
At this point I just pushed it down till the bridge bottomed on the other valves and adjusted the rocker. The other cylinders adjusted fine until I got to #1.
Second major issue: On cylinder #1 with the adjustment screw all the way out for the intake valve, the rocker still contacts the crosshead (bridge).
This is where I stopped because it didn't seem right at all. I'm stumped as I've never torn into a diesel before and I can't find ANY info on the net to fix the issue. Any thoughts?

And this might be a dumb question but the TM is pretty vague, but the left valves are intake and the right are exhaust on every cylinder right? Or are the rockers with the rivet on the end (the far left and far right per rocker housing) the exhaust valves?

As you can see I'm no expert with diesels. The only thing I had was a Deuce but I never had to dig into it this much.

 

[WillWagner]

Sounds like you have a dropped valve or two.
Thake the rocker boxes off and see if the offending cylinders have springs that are shorter or taller than others.

 

[augiedoggy]

Hey there!
Did you read this thread?

http://www.steelsoldiers.com/5-ton-up/73256-nhc250-valve-injector-overhead-adjusting.html

Will has given a little class on these engines and after reading this I have a much better understanding (thanks Will!!)

I noticed that all of the adjustment screws stick up from the rockers about the same. If one didn't look like the others something was wrong!

I was setting the injector for the cylinder when both valve rockers were loose for that cylinder to get it running better

good luck again, I'm sure the other pros here will jump in and get you going again.

Oh, there's Will now!
Shhhhh........ he's typing.........

 

[Kalashnikov]

Sounds like you have a dropped valve or two.
Thake the rocker boxes off and see if the offending cylinders have springs that are shorter or taller than others.

I don't recall the springs in cylinder 1 being longer than the others but #2 exhaust spring is definitely longer. Is there anyway to tell if the other valves are ready to go as well?

Hey there!
Did you read this thread?

http://www.steelsoldiers.com/5-ton-up/73256-nhc250-valve-injector-overhead-adjusting.html

Will has given a little class on these engines and after reading this I have a much better understanding (thanks Will!!)

I noticed that all of the adjustment screws stick up from the rockers about the same. If one didn't look like the others something was wrong!

I was setting the injector for the cylinder when both valve rockers were loose for that cylinder to get it running better

good luck again, I'm sure the other pros here will jump in and get you going again.

Oh, there's Will now!
Shhhhh........ he's typing.........

Yea, I was using that thread as my guide otherwise I'd be

 

[WillWagner]

Hey there!
Did you read this thread?

http://www.steelsoldiers.com/5-ton-up/73256-nhc250-valve-injector-overhead-adjusting.html

I noticed that all of the adjustment screws stick up from the rockers about the same. If one didn't look like the others something was wrong!

I was setting the injector for the cylinder when both valve rockers were loose for that cylinder to get it running better

good luck again, I'm sure the other pros here will jump in and get you going again.

Oh, there's Will now!
Shhhhh........ he's typing.........

Good eye! Most people don't even think of looking at adjusting screw heights. You get yours running better?

 

[jimk]

...but the left valves are intake and the right are exhaust on every cylinder right?...

Easy to remember when you look at the intake manifold. Those 3 ports feed into the middle of each cylinder head (rocker boxes when you're looking from above). The intake ports are Siamesed in the center of each cylinder head.

 

[augiedoggy]

Good eye! Most people don't even think of looking at adjusting screw heights. You get yours running better?

Hey Will, haven't got to it yet but as soon as i get time......I'm all over it!!!
Like rambo diesel mechanic!!
picture.....feeler gauges and torque wrench in holsters grease smears on face....

 

[goatijoe]

where are you trying to turn the motor at if you are on the crank it is hard to do. do that at the acc drive pully on the left side if im not forgetful i beleave its a 1 3/16 or a 1 1/2 or so its been a while since i have worked on a cummins. and another helpful hint on adjusting the valves is get you 2 feeler gages if im not forgetfull agian its a .14 on the intake and a .27 on ext just take those and bend them to about 45 degrees and it will fit in the rocker box a lot better than you having it strait. did you bottom the injectors out while adjusting them if you didnt you wont be getting all the pressure and the fuel delevery from them thus lack of power.
As the ol swamp hick in water boy says "you can do it"

 

[gimpyrobb]

Like rambo diesel mechanic!!
picture.....feeler gauges and torque wrench in holsters grease smears on face....

Oh my god, you dork!

BWAAAAAAAAAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!

 

[gimpyrobb]

OH!

 

[goatijoe]

haha if theres a truck motor you can work on its a cummins thank god hes not trying a cat or even better if its a detroit. eather of those it be you cant do it.

 

[augiedoggy]

Oh my god, you dork!

BWAAAAAAAAAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!

I know I'm a dork Chris......I can't help it!

 

[Kalashnikov]

Easy to remember when you look at the intake manifold. Those 3 ports feed into the middle of each cylinder head (rocker boxes when you're looking from above). The intake ports are Siamesed in the center of each cylinder head.

I kind of figured that but didn't realize it till after I adjusted the valves already!

where are you trying to turn the motor at if you are on the crank it is hard to do. do that at the acc drive pully on the left side if im not forgetful i beleave its a 1 3/16 or a 1 1/2 or so its been a while since i have worked on a cummins. and another helpful hint on adjusting the valves is get you 2 feeler gages if im not forgetfull agian its a .14 on the intake and a .27 on ext just take those and bend them to about 45 degrees and it will fit in the rocker box a lot better than you having it strait. did you bottom the injectors out while adjusting them if you didnt you wont be getting all the pressure and the fuel delevery from them thus lack of power.
As the ol swamp hick in water boy says "you can do it"

Yea, I've been using the accessory drive to turn it. The nut that was on it was 1 1/4" but it stripped out and the nut I got from Cummins is 1 5/16." Agrred on bending the feelers. It worked well.

Looks like I'll be pulling the heads soon to do the valves before I can finish adjusting everything.

 

[augiedoggy]

Yea, I've been using the accessory drive to turn it. The nut that was on it was 1 1/4" but it stripped out and the nut I got from Cummins is 1 5/16." Agrred on bending the feelers. It worked well.

Looks like I'll be pulling the heads soon to do the valves before I can finish adjusting everything.[/QUOTE]

So the new cummins nut held torque?

And if you pull the heads go ahead and replace the casting/freeze plugs because one of mine had a pinhole rusted in it between the heads!

 

[m139h2otruck]

Best guy I know for working on Cummins is Bill Jones of Deerfield NH. Had a high HP 855 back in the late '80s early 90s that would spin the tires at speed with 100,000# on. Great guy.

 

[Kalashnikov]

I got the truck back together and now it won't start. I know it's a fuel issue because it runs with starting fluid. The truck is primed and the lines have fuel: the filters are full and the line at the tanks is. The electric solenoid is bypassed as well and still nothing.

 

[augiedoggy]

I got the truck back together and now it won't start. I know it's a fuel issue because it runs with starting fluid. The truck is primed and the lines have fuel: the filters are full and the line at the tanks is. I had the manual cut off pulled all this time. Is it possible it got stuck internally even though it is pushed forward? The electric solenoid is bypassed as well and still nothing.

Have you tried taking the fuel line loose or off of the fuel cut solenoid and cranking engine to see if any fuel squirts out?

and then there's the thing with the small tank of fuel under hood feeding directly into pump inlet.....

good luck

 

[goatijoe]

on that solenoid there is a wheel or a screw coming out of it turn it. it will only go one way should go in and it will open the solenoid up and by pass it. its a fail safe to get home and to cut it off vis versa and it will shut. the valve shouldnt stick but theres no telling with them are you sure your getting power to the solenoid. that is the only valve besides the return check valves in the back of the last head.

 

[Kalashnikov]

Have you tried taking the fuel line loose or off of the fuel cut solenoid and cranking engine to see if any fuel squirts out?

and then there's the thing with the small tank of fuel under hood feeding directly into pump inlet.....

good luck

Yea, I'm getting fuel returning to the tank and to the IP/head.

It seems like the next step is to increase the torque on the injectors because they aren't injecting fuel.

 

[goatijoe]

is there a cummins place near you. im not trying to sound smart but its worth every penny on a book for that motor. cummins has great illistrations in them and step by step and even a section on trubleshooting a problem you have. i dont know what that book runs but like i said its worth it and the injectors i think are preloaed when you tork them with in. lbs not ft. lbs that is one of the best motors ever built. its the same block they ran for over 60 years started off as a 200 hp, then 250 , 300, 400 and then 500 plus with the n14 celect. **** govenment shut it down cuz it would not meat the emmissions.