I can say in the USAF working fighter jets, it was common to come across parts that had different part numbers or stock numbers. This was generally due to different manufacturers. These would usually cross reference to original part numbers. So those connecting rods may have just been from 2 different manufacturers, but all built to the same specifications.
Now that you have experienced coolant failure in 3 of your engines, what type of coolant are you going to put in? I'm seriously thinking of going with Evans waterless coolant.
Haven't looked into that but in my testing even thinner has not make any effect on the seals. The only thing that has messed with the seals has been heat. I am going to take one of the old pistons, drop it in a trash bore and heat it from the top with a torch. I want to see if it expands enough to stick in the bore at around 1000F. These motors don't have oil squirters to cool the underside of the pistons so maybe it is a heat issue. No turbo, standard fuel settings and not being worked hard at time of failure but at this point I am running out of ideas. If they don't stick then...IDK.
Heat was my first impression when I saw those seals. Sounds like you want to perform a good test. But I'm just "guessing" here, the scoring of the pistons was due to the lack of lubricity of the oil with the amount of water in it. Sure common sense would dictate that all the cylinders would show the same amount scoring but not necessarily, there are too many variables between each cylinder/piston. Just microns in measurement, the amount of lubricate delivered to each cylinder, the percentage of oil to water mix to each cylinder would dictate a scored cylinder and a non-scored cylinder/piston. The other thing to consider is just simply age, how old are those seals? Most of these engines in the civilian world accumulate hundreds of thousands of miles in a few years where age is not a factor. Wear on the engine components determine engine rebuild time. As you mention before in one of your videos "the engines in these military trucks might see a 1000 miles in a decade" therefor I'm thinking these engines are out living the life of the seals. But from what you have seen from the inside of these engines, the amount of pitting in one, the corrosion buildup in the other, the waterless coolant sounds good. There are a few good videos on Evans waterless coolant. but my concern is heat buildup. Evans coolant has a higher viscosity therefore heat transfer is less from the metal of the engine to the coolant itself. I'm worried about the trany oil and engine oil overheating. If you decide to watch those videos, I would value your opinion greatly.
Weell, I found this blog that answers all the questions on Evans coolant.www.ffcars.com/forums/17-factory-five-roadsters/302124-you-using-evans-waterless-coolant.html
I have a 5 ton dump with this 250, had an issue with the fuel pump, on start up the truck would go to full throttle, not running away, just full throttle. I had the pump rebuild, rebuilder said it was really nasty inside. Put the pump back on the truck and now it will not start. The fuel was really nasty, so I am assuming something got passed the pump and to the injectors. I have cleaned all lines to the head and return lines. I have fuel to the head but no fuel coming out of the return line. I have everything airtight on the pump side. Do you have any suggestions of what my next move should be, is there something in the head the could be blocked, do you think all injectors could be blocked? Any info would be much appreciated. Thanks Tim
@@acme663ryo I have pressured the tank to get air out. I then took a bucket of fuel and clear hose to the pump to double check no air getting in. I have no fuel coming out of the return line. Took inlet line loose at head, and I have fuel there but none coming out of the return.
@@timbrooks8616 I think if injectors were plugged you would get everything coming out of the return. I mean no disrespect but go fully actuate the manual valve then reset it. Watch that the lever is actually moving the valve and hasn't come loose. You should get buckets of fuel, a real mess on the pump output when you bleed. If you are then go injector to injector again, should be same. If it is then put pressure gage on pump output and check while cranking. Isn't there a pressure regulator on the return? If so see if you get anything from before vs after. You should have 26psi out of the pump to the front head at 500rpm. Email or text me and I will send pictures of the book. Info in description of this or a newer video.
I came here looking for 1 answer. I feel like I already know the answer but... upon looking over the parts for my NHC250 I found they sent me 3 ring pistons. My originals are 4. My new ring kits are 4, PN: 4089810. Was there a change at any point that led to the use of 3 ring pistons in these engines? Or was I just given the wrong parts?
@@acme663ryo So it turns out they discontinued the 4 ring pistons. So if you have to replace a piston you'll get a 3 ring and you'll have to do them all. Just fyi..FYI... at least that's the line I got.
@@jefftruckshop6591 when you pull the first one out weigh it against the old 4 ring, if the same you can probably just swap one if you like. The rotation internals are just stupid tough in the 855. That and the NH250 is such a detuned slug, not even close to what it can take.
@@acme663ryo I should have when I had it. It's gone now. That's no joke with the 250. The thing is so overbuilt. Surprised me in a few areas. Mine is a Detroit Diesel shop but we do get a few other makes in there. This little Cummins did impress me.
Ditto on the classic radio station, love it. As for the engine, I contemplated sourcing one of the NHC250s for my federal's repower, but judging by this video, its WAY to big for the old trucks engine bay. One other thing, where did the video's audio come from?
![🔴 ฟุตบอลแชมป์กีฬา 7HD แชมเปียน คัพ 2024 [รอบรองชนะเลิศ]](http://i.ytimg.com/vi/zPm8ClLVhoE/mqdefault.jpg)
amazing :) , but where you part 3 ? i want to see valves and injectors adjustment
Love your videos- this gives me perspective on how physically large the 250 really is.
Big girl. Putting the mains on and torquing them to 300lbs was an eye opener.
NelsonStudios is it bigger than the 855
I can say in the USAF working fighter jets, it was common to come across parts that had different part numbers or stock numbers. This was generally due to different manufacturers. These would usually cross reference to original part numbers. So those connecting rods may have just been from 2 different manufacturers, but all built to the same specifications.
a couple of guys doin a marathon cantsee wats goin on boring ,oh sleeving
Now that you have experienced coolant failure in 3 of your engines, what type of coolant are you going to put in? I'm seriously thinking of going with Evans waterless coolant.
Haven't looked into that but in my testing even thinner has not make any effect on the seals. The only thing that has messed with the seals has been heat. I am going to take one of the old pistons, drop it in a trash bore and heat it from the top with a torch. I want to see if it expands enough to stick in the bore at around 1000F. These motors don't have oil squirters to cool the underside of the pistons so maybe it is a heat issue. No turbo, standard fuel settings and not being worked hard at time of failure but at this point I am running out of ideas. If they don't stick then...IDK.
Heat was my first impression when I saw those seals. Sounds like you want to perform a good test. But I'm just "guessing" here, the scoring of the pistons was due to the lack of lubricity of the oil with the amount of water in it. Sure common sense would dictate that all the cylinders would show the same amount scoring but not necessarily, there are too many variables between each cylinder/piston. Just microns in measurement, the amount of lubricate delivered to each cylinder, the percentage of oil to water mix to each cylinder would dictate a scored cylinder and a non-scored cylinder/piston.
The other thing to consider is just simply age, how old are those seals? Most of these engines in the civilian world accumulate hundreds of thousands of miles in a few years where age is not a factor. Wear on the engine components determine engine rebuild time.
As you mention before in one of your videos "the engines in these military trucks might see a 1000 miles in a decade" therefor I'm thinking these engines are out living the life of the seals.
But from what you have seen from the inside of these engines, the amount of pitting in one, the corrosion buildup in the other, the waterless coolant sounds good. There are a few good videos on Evans waterless coolant. but my concern is heat buildup. Evans coolant has a higher viscosity therefore heat transfer is less from the metal of the engine to the coolant itself. I'm worried about the trany oil and engine oil overheating. If you decide to watch those videos, I would value your opinion greatly.
Weell, I found this blog that answers all the questions on Evans coolant.www.ffcars.com/forums/17-factory-five-roadsters/302124-you-using-evans-waterless-coolant.html
Coming together nicely. It will be back up and running soon.
I was looking forward to this!
Dry verse lubed fasteners is about 30% difference. is what i seen when working with big stuff up 4" bolts. keep up the good work.
I have a 5 ton dump with this 250, had an issue with the fuel pump, on start up the truck would go to full throttle, not running away, just full throttle. I had the pump rebuild, rebuilder said it was really nasty inside. Put the pump back on the truck and now it will not start. The fuel was really nasty, so I am assuming something got passed the pump and to the injectors.
I have cleaned all lines to the head and return lines.
I have fuel to the head but no fuel coming out of the return line. I have everything airtight on the pump side.
Do you have any suggestions of what my next move should be, is there something in the head the could be blocked, do you think all injectors could be blocked?
Any info would be much appreciated.
Thanks
Tim
First check that the manual fuel valve hasn't been bumped. Happens all the time. It does not reset from the dash, you have to go under the hood.
@@acme663ryo Nope that's not it, I have fuel all the way to the front of the head.
@@timbrooks8616 how are you bleeding, pressurize the fuel tank or cranking?
@@acme663ryo I have pressured the tank to get air out.
I then took a bucket of fuel and clear hose to the pump to double check no air getting in.
I have no fuel coming out of the return line.
Took inlet line loose at head, and I have fuel there but none coming out of the return.
@@timbrooks8616 I think if injectors were plugged you would get everything coming out of the return. I mean no disrespect but go fully actuate the manual valve then reset it. Watch that the lever is actually moving the valve and hasn't come loose. You should get buckets of fuel, a real mess on the pump output when you bleed. If you are then go injector to injector again, should be same. If it is then put pressure gage on pump output and check while cranking. Isn't there a pressure regulator on the return? If so see if you get anything from before vs after. You should have 26psi out of the pump to the front head at 500rpm. Email or text me and I will send pictures of the book. Info in description of this or a newer video.
Why did you not drop the crank and redo your seals and check your bearing clearances?
Motor ha only 5000 miles when it lost the liner do to EGTs. Everything else was flawless.
I came here looking for 1 answer. I feel like I already know the answer but... upon looking over the parts for my NHC250 I found they sent me 3 ring pistons. My originals are 4. My new ring kits are 4, PN: 4089810. Was there a change at any point that led to the use of 3 ring pistons in these engines? Or was I just given the wrong parts?
Call and confirm but it sounds like wrong parts.
@@acme663ryo So it turns out they discontinued the 4 ring pistons. So if you have to replace a piston you'll get a 3 ring and you'll have to do them all. Just fyi..FYI... at least that's the line I got.
@@jefftruckshop6591 when you pull the first one out weigh it against the old 4 ring, if the same you can probably just swap one if you like. The rotation internals are just stupid tough in the 855. That and the NH250 is such a detuned slug, not even close to what it can take.
@@acme663ryo I should have when I had it. It's gone now. That's no joke with the 250. The thing is so overbuilt. Surprised me in a few areas. Mine is a Detroit Diesel shop but we do get a few other makes in there. This little Cummins did impress me.
A is that small cam turned up or is it stock
Military stock so tiny valves, flat cam. Egts are crazy with these motors.
I hated these dogs when I was in the Marine Corps, but I hated the 8V-71T in the Dragon Wagons more.
Ditto on the classic radio station, love it. As for the engine, I contemplated sourcing one of the NHC250s for my federal's repower, but judging by this video, its WAY to big for the old trucks engine bay. One other thing, where did the video's audio come from?
th-cam.com/users/NoCopyrightSounds
Head bolts get a special lube known popularly as peanut butter.
Lubriplate
can u help me if what is the best valve clearance for intke exhaust in nh250 cummins
You have to figure out what injectors you have first, topstop or non-topstop.
jun ramos I will try to get you that info today and post it here and in description.
NelsonStudios im looking forwrd to it
jun ramos I am going to need an email address for you to send the pdf documents
what is the radio station called. they have great music.
Just the local classic station in Kalispell. To bad the videos would get flagged if I just let it play.
5:58 obnoxiously loud "BAH BAH BAAAAH" lol
tining small cam