Engine Locked? | 855 Cummins

[WillWagner]

It sounds OK to me. Rather than pull injectors, if you are curious if there is some sort of damage, remove the oil filter and cut it open. Look between the pleats for chunks. This will make it so you don't need to go into the engine. I'd run it.

 

[162tcat]

Sounds normal to me. Run it hard and have fun. No reason to rip it apart unless you want to for the fun of it.

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[Stranger]

Ditto the above. Sounds fine. Maybe it just sounds different to your ears?

 

[Zoidsfan77]

My ears are untrained when it comes to these big diesels. I am just going off my gasser knowledge, which I know are very different.

As far as running it, it still has a low power problem, which I attribute to injectors for a few reasons. I don't think it is an air in fuel problem, as I have a new pump to filter line, and a new spin-on fuel filter assembly. Power is unchanged from before I installed these items. I checked throttle travel, it too seemed okay.
My other reason for pulling injectors is my fuel system was extremely filthy. The truck sat, unstarted for 2+ years, and all the fuel system parts I have replaced where nasty. I have been running the Cummins injector cleaner, which has made an improvement in smoke and idle, but power is unchanged. I am reasonably confident I have set the overhead correctly.

Unless I have a pump problem, injectors are all I can think of. They are not terribly expensive (about $60 for remans), so for piece of mind I thought I would replace them.

This all started with me trying to figure out my low power issue.

 

[162tcat]

How do you know it's low on power? It's a big truck with a 250 horse diesel. Have you driven others?

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[Zoidsfan77]

How do you know it's low on power? It's a big truck with a 250 horse diesel. Have you driven others?

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No I have not, so I guess I don't truly know for sure, but is sure seems that way. It struggles to hit 55mph, even on long, flat stretches of road. It must be driven at full throttle to reach anything above 45. I am downshifting at the slightest inclines. I estimate 0-55MPH time is greater than 60 seconds, unloaded on level pavement.

I know it doesn't have much power for its weight, but my truck weighs about 23,000lbs. I know a M816 wrecker weighs a **** of a lot more, but they can reach 50mph. I can't imagine going any more than 25mph with 5 tons in the back at this power level.

I once was at a stoplight next to a small daycab international tractor with a lowboy loaded with heavy construction equipment. He was not racing me, just casually accelerating on his merry way. I however was giving it all she had, and that tractor blew my doors off and wasn't even trying. He was probably at around 50 mph by the time I broke 30.

 

[162tcat]

No I have not, so I guess I don't truly know for sure, but is sure seems that way. It struggles to hit 55mph, even on long, flat stretches of road. It must be driven at full throttle to reach anything above 45. I am downshifting at the slightest inclines. I estimate 0-55MPH time is greater than 60 seconds, unloaded on level pavement.

I know it doesn't have much power for its weight, but my truck weighs about 23,000lbs. I know a M816 wrecker weighs a **** of a lot more, but they can reach 50mph. I can't imagine going any more than 25mph with 5 tons in the back at this power level.

I once was at a stoplight next to a small daycab international tractor with a lowboy loaded with heavy construction equipment. He was not racing me, just casually accelerating on his merry way. I however was giving it all she had, and that tractor blew my doors off and wasn't even trying. He was probably at around 50 mph by the time I broke 30.

That's not far off. Only 5 gears, no turbo. How old is the diesel? Maybe a little low on power but don't throw money at the problem. Clean the system and adjust. Install an EGT gauge. It's likely just out of adjustment. These are very simple engines. Get that dialed in and turn the power up. Best way to bump up power is throw a turbo from a big cam 350 or similar on it. Depending on how you drive, you can bump it to 300+ horse.

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[162tcat]

And just as a comparison, my Mack CH13 with end dump scaling out at 85-90k will hit 60 before my stock NHC 250 M923 will empty. My 8.3 truck is a rocket though!

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[Stranger]

No I have not, so I guess I don't truly know for sure, but is sure seems that way. It struggles to hit 55mph, even on long, flat stretches of road. It must be driven at full throttle to reach anything above 45. I am downshifting at the slightest inclines. I estimate 0-55MPH time is greater than 60 seconds, unloaded on level pavement.

In my experience, what you describe is normal for an unmodified NHC 250.

It is a 14.0 L engine rated for 250 HP. It is not going to be "faster" than a more modern 8.X L engine with the same HP (or higher).

With regard to empty versus loaded acceleration, I found very little difference. I loaded 8,000 lbs of tires in the back of mine and was worried about getting past 40 mph. However, it accelerated and behaved the same as it did empty. Finally got up to ~55 mph on a long flat stretch. However, going up hills it was down to 45-50.

 

[Zoidsfan77]

In my experience, what you describe is normal for an unmodified NHC 250.

It is a 14.0 L engine rated for 250 HP. It is not going to be "faster" than a more modern 8.X L engine with the same HP (or higher).

With regard to empty versus loaded acceleration, I found very little difference. I loaded 8,000 lbs of tires in the back of mine and was worried about getting past 40 mph. However, it accelerated and behaved the same as it did empty. Finally got up to ~55 mph on a long flat stretch. However, going up hills it was down to 45-50.

45-50 Up a hill, will not happen in my truck, for sure. 35 maybe. I live in Ohio also, so a hill to me is not really a hill to some.
But maybe you all are right.
I will post an acceleration video sometime.

 

[BigDawg41]

I played your video,cranked up the sound and closed my eyes. I thought I was listening to my truck! Mine sounds the same and has that constant deep knock at idle that every other 250 does that I listen to. As far as power,these are big,very powerful but SLOW trucks. Whenever I jump in mine if I haven't had it out in awhile,I get aggravated at first trying to push it faster and trying to get up to speed driving it like a race car. I soon realize to just settle in,take it easy,roll through the gears and just enjoy the scenery. I live in a very hilly area of NY and when trying to pull a hill I usually can only achieve 4th gear,sometimes only 3rd. Man I miss my truck. It's been in storage since beginning of November. I will go play your video again now and dream the snow melts soon.

 

[swiss]

This has been a good thread to read. Lots of good common sense troubleshooting items and then a big AHA at the end when sometimes we attack things we think are a problem and not really a problem

Thanks everyone who contributed the good ideas

 

[sandcobra164]

My experience with the NHC-250 is somewhat different. I think he is a little low on the power spectrum compared to my truck. I have an M923A0 that I put 14R20's on. I can get to 60 in about 30 seconds and have pulled hills at 55 mph with 26,000 pounds in tow. I had modified the pump by drilling out the tamper proof ball in the throttle shaft and unseating the fuel screw by about 3/4 of a turn. When the pump puked the front seals out and filled the crankcase with diesel, I had it rebuilt. The shop that did the work flowbenched it and turned it up even more. I asked if my attempt to turn it up resulted in the failure and they claimed it wasn't even turned up to factory Cummins specs. One thing they noted was that the "emergency shutoff" valve did not stop at center when pushed all the way forward. Could just be the one on my truck but likely many more of them. Before I reinstalled the pump, I inserted a drill bit backwards and added a mark with a hacksaw blade so that I could index where I need to set the "emergency shutoff" to on the top of the pump to "true center" of the slot in the shutoff. They also upped the fuel rate 10% and I certainly noticed the difference in performance. The heavy towing comparison was done before the pump work. For what it's worth, having the pump remanufactured locally only cost $350 or $375, can't remember exactly but that's in the ball park.

 

[Shirehorse]

After watching the video, she's purring like a wounded jungle cat, I.E. Just like what both of my Cummins powered trucks sounded like at idle.

~Brian

 

[farmerboywyotech]

45-50 Up a hill, will not happen in my truck, for sure. 35 maybe. I live in Ohio also, so a hill to me is not really a hill to some.
But maybe you all are right.
I will post an acceleration video sometime.

My m925 with the nhc250 empty will pull any hill around here in michigan at 60 65 mph. Loaded which is anywhere from 5 tons up to almost 20 tons with the trailer loaded will still pull hills at 50 as long as I hit it moving. A strong head wind is worse than a full load. Then I'm lucky to see 55. Some days are better than others though. Some times its a short shifting gutless turd and other days it pulls with authority no matter what I'm doing. It's pretty consistent with loads less than 15,000 though.

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[red]

Another update my friends!
The other day I went to start the truck, and much to my surprise, it started right up. Hit the starter for maybe 2 seconds.This time I had the primer lever pushed in...
I did not record startup, but here are my temp readings after a few minutes of idling.
https://youtu.be/q_QKT2n0KKs
Engine still knocks though. I ran the engine for about an hour. I did not put any load on it.
Still planning on pulling injectors and looking into cylinders.Can this be done without the special tool, or should I spend the $150 bucks?

Going off the video it sounds like it's running fine. Older diesel engines (non common rail fuel injection) are noisy and make alot of clatter. The smoke out of the exhaust when you step on the throttle is a little bit dirty but as you mentioned in another thread that the fuel system in this truck was filthy, probably from sitting for a long time. Run a couple tanks worth of fuel through it (keep adding one of the fuel system cleaners such as B12 or Seafoam for each tank). That will clean out the fuel system and clean up the exhaust some.

While you are going through about 4-5 tanks of fuel/cleaner, install an EGT gauge. Some of the fuel systems on these trucks were turned up by the military, others were turned down. Wait to do any fuel system work until after 4-5 complete tanks of fuel to clean it out.

 

[Cape Coastie]

Hey Zoidsfan,

lots of good info here but I have a question I haven't seen dealt with here that I experienced on my NHC 250 in my M923. Have you checked your fuel tank vent? When you take your fuel tank cap off to refuel after running is there a vacuum? My vent was plugged with a mud dauber nest and I was loosing power, not as much pickup and less top end. Went to refuel and I had a serious vacuum In the tank. It flexed several times before I got the cap all the way off. Removed the vent at the top of the intake stack and blew out the blockage. This has happened twice to me and after the second time I added a small filter to the vent line and haven't had a problem since. I know the 814 has a different stack arrangement but might be a quick check you could do. Good Luck. By the way my truck sounds a lot like your video as others have said.

 

[Zoidsfan77]

Hey Zoidsfan,

lots of good info here but I have a question I haven't seen dealt with here that I experienced on my NHC 250 in my M923. Have you checked your fuel tank vent? When you take your fuel tank cap off to refuel after running is there a vacuum? My vent was plugged with a mud dauber nest and I was loosing power, not as much pickup and less top end. Went to refuel and I had a serious vacuum In the tank. It flexed several times before I got the cap all the way off. Removed the vent at the top of the intake stack and blew out the blockage. This has happened twice to me and after the second time I added a small filter to the vent line and haven't had a problem since. I know the 814 has a different stack arrangement but might be a quick check you could do. Good Luck. By the way my truck sounds a lot like your video as others have said.

Interesting! I have not checked my tank vent, but I have never noticed any suction when removing the cap either.
I will check it, probably tomorrow.
Good suggestion.

 

[Zoidsfan77]

I played your video,cranked up the sound and closed my eyes. I thought I was listening to my truck! Mine sounds the same and has that constant deep knock at idle that every other 250 does that I listen to. As far as power,these are big,very powerful but SLOW trucks. Whenever I jump in mine if I haven't had it out in awhile,I get aggravated at first trying to push it faster and trying to get up to speed driving it like a race car. I soon realize to just settle in,take it easy,roll through the gears and just enjoy the scenery. I live in a very hilly area of NY and when trying to pull a hill I usually can only achieve 4th gear,sometimes only 3rd. Man I miss my truck. It's been in storage since beginning of November. I will go play your video again now and dream the snow melts soon.

Perhaps I will record a better one and post it here
I spend a fair bit of time in 3rd gear.
I don't know how much snow there is left. Been really mild here in Ohio, but I know NY is usually... not.

 

[Zoidsfan77]

Going off the video it sounds like it's running fine. Older diesel engines (non common rail fuel injection) are noisy and make alot of clatter. The smoke out of the exhaust when you step on the throttle is a little bit dirty but as you mentioned in another thread that the fuel system in this truck was filthy, probably from sitting for a long time. Run a couple tanks worth of fuel through it (keep adding one of the fuel system cleaners such as B12 or Seafoam for each tank). That will clean out the fuel system and clean up the exhaust some.

While you are going through about 4-5 tanks of fuel/cleaner, install an EGT gauge. Some of the fuel systems on these trucks were turned up by the military, others were turned down. Wait to do any fuel system work until after 4-5 complete tanks of fuel to clean it out.

When you say some were turned down, would that mean a larger button? I am curious as to what size button our trucks are supposed to have.