NHC-250 injection pump woes - PT pump in ruins

[OPCOM]

As I mentioned in the thread http://www.steelsoldiers.com/milita...-road-trip-dfw-chester-il-dec-26-jan-9-a.html , the engine has not run very smoothly, was almost impossible to start without ether, and would not keep prime after 45 minutes.

Here are pictures of the PT pump innards on my NHC250.. These probably explain why the truck would not stay primed and why it ran so poorly. This is fixed now, at the cost of a complete pump rebuild. It looks like some kind of grit made its way through the pump and ruined it. The grit and much scoring is evident. The pump shop said they found what looked like brass or bronze dust and shavings. I do not know what the white grit is. The pump was supposedly 8000 miles old. Same as the engine. The engine now runs absolutely spec. I'd be interested in opinions as to what happened here.

top right: gear pump, fuel
clockwise:
- governor shaft, gear, and weights
- shaft, FP drivepump drive shaft
- ? shaft
- ? bushing
- shutdown valve

 

[cranetruck]

Good to see it fixed Patrick.
I'm always concerned about hard particles from rust etc in the fuel tank, since there are several components on the multifuel IP/FDC that can be harmed by them getting past the filters. I have installed a magnetic fuel filter (homemade) in the line to help stop the micron size metallic particles.
Fuel tank maintenance would be my first suggestion for you...

 

[hndrsonj]

I am scared to ask what that cost to get rebuilt. Did you think of a used one from Red River Parts in Texarcana? (that's where my deuce one came from)

 

[OPCOM]

Do I need to remove the tank? In any case, first I better look inside again with a flashlight. It seems to be clean but who knows, the whole thing cannot be seen.

I did away with the stock filter and put a new spin-on one in on the advice of the shop. They did the job, made up the bracket and it looks great. I believe the new type filter is going to be much better at catching stuff than the old cannister. The NHC-250 has only one filter, so it better be good. It is the same kind of filter they use when overhauling engines for city trucks and motor homes, where they put themselves in a position to have to guarantee it.

On another topic the tach cable is very hard to turn, and it is not working now since the poump was rebuilt. The foreman said to replace the cable. I do not understand why it would have worked on the pump before, and not now, and I said so. What is the deal with that? Why would the pump turn the cable before and not now? Could the cable have been somewhat bad? This bothers me and I have by no means let them off the hook but I want to understand this. I will be unhappy if I replace the tach cable and the tach still does not work.

It cost $1600 for the pump rebuild to as-new alone due to being so trashed. There are also costs for heavy duty fuel lines and filter, fabbing the filter mount (looks like a manufactured item), and labor. I did not go the cheap way on this item. I opted for the rebuild so that an expert company would be responsible for getting this done right. That is why I have no fear of bringing up the tach cable as the tach was working when the truck was dropped off and that makes them liable for it to some degree. When I have time I will remove it and inspect it. Does anyone know if this is the kind of cable where the inside flexible shaft can be slid out and cleaned?

 

[doghead]

How does it start now(cold)? I also am curious of the cost to rebuild.

 

[jwaller]

I once had a hard to turn cable and I removed it, cleaned it and lubed it, then it worked flawlessly.

 

[hndrsonj]

You should be able to disconnect and easily turn the cable by hand. You can remove and lube the cable as long as the outer casing is not chewed up on the inside.

 

[OPCOM]

it started 'cold' today without delay. 60 degrees.

 

[Rene M]

To me, it looks like water contamination.. I sent the link to a buddy who works in a fuel shop and he also agrees. Water/rust contamination. you may have some down stream lines with some rust in them. It may be why the last motor was pulled.
The #1 killer of Diesel engines is h2o....

 

[OPCOM]

By downstream, where do you mean? tank-to-pump? elsewhere?

That is very interesting and I thank you for getting opinions. Before the repairs, it had some 6-8 tanks of fuel run through it. The repairs included completely new and modern type of fuel line from the tank to the pump, a completely new fuel filter and base (ditched the stock cannister). The return is copper with some rubber hose spliced in where needed. We did not find evidence of rust when doing that mod, but I admit we were not looking for it specifically.

So aside from anything that could still be lurking in the tank which I must check more carefully and hopefully clean, everything from the tank to the pump is new and properly done. I have bypassed and removed the original mess of lines and valve that the M818 originally had. The second fuel tank is gone, no need for it. I hope this will put an end to the problem for good.

 

[cranetruck]

Patrick, does your new filter have the "water separator" feature? The original had a drain at the bottom for this if I'm not mistaken. Micron rating should be about 5 or so.

The tank has baffles within and it would be hard to inspect 100%. How is the inside top of the tank? If you filled it to the max on your trip, perhaps stuff from the upper parts of the tank contaminated the fuel.

 

[shootiniron]

Is the fuel filter spin-on conversion a necessary thing if your "not" having any issues?

 

[54reo]

That tank should be spotless (as in not an ounce of anything in there).

Both tanks were brand new.

 

[doghead]

Maybe that's why they were new! The old ones may have been extremely rusty or dirty?

 

[OPCOM]

To be clear, the destruction of the pump was done before we even bought the truck. The truck did not run, and said "won't start" at GL. It was bought with this defective pump, and the pump did not deteriorate further once we had the truck. It just "was". I think it was a bad rebuild, or was damaged somehow (water?) after rebuild, or the truck got water in the tank and they ran it, but in any case, the pump must have been like that when the truck was bought. It is frankly amazing that it ran at all.

The new fuel filter was necessary as the old one had a cracked housing top section.
Speculation? Water got in there?

The new filter is of the type that has a water separator. It is 10 micron, as spec by Cummins. Is there a 5 micron version, and would it fit the same? I guess I can look it up. But what is the micron rating on the original filter? This filter is used with the Cummins ISM engine.

 

[OPCOM]

and

 

[jwaller]

the stock 3401 fuel filter is a 12 micron rating. so your doing a little better with your new setup. let us know how much water you see coming out of it.

 

[OPCOM]

I have some evidence I was grossly overcharged by the diesel shop or both parts and labor.
I don't want to say more now, but the job was very costly ($1600 for the pump does not include labor and is not the entire bill by a mile), the labor was far more than quoted as was the pump, although a lame excuse was offered. Like anyone else I went in, paid the bill, and did not think much of it till I got home and was reviewing it, and someone said something about it that made a lot of sense.

These is also a competence issue of them letting two of my batteres die by cranking till empty, and then not properly recharging. I had told them it was 24V at least 3 times, but I believe they just put 12V on to two top batteries, nothing for the bottom ones. I am trying to recharge them now.

When they could not crank it, (probably on their 12V cranking supply connected only to the top batteries), they checked the amps, and decided that 800A and no movement means I need a new starter. (that will happen if there is some voltage applied, but not enough to turn it. I had to explain that a universal-wound motor wound like a starter motor uses huge amounts of current when not moving. Shouldn't they know that?) They wanted to sell me a starter and said it was burned. I told them I worked with that starter for over two weeks and there was nothing wrong with it, and that if anything was burned it happend under their responsibility. Then they said it was a wire connection. to the starter.

I now recall they left the glow plug ON shortly after my bringing it in, and I have not checked to see if the brand new $50 plug was burned out. This is where the suspicions of the place making mistakes and just slapping the customers for them began.

This was followed by a bill with $800 too much labor (over what was quoted) and as much as $1100 too much for the pump. So this has to be corrected. If it is cheerfully corrected, I will need say no more about it because people make mistakes. If it is not corrected (or somehow explained in satisfying itemized detail, which I believe I have a right to at this point) then I will have do do something about it.

 

[OPCOM]

the stock 3401 fuel filter is a 12 micron rating. so your doing a little better with your new setup. let us know how much water you see coming out of it.

That is good to know. I never got much water from the M35's primary. Here in TX I do not seem to see this issue. I was told to check for water when the truck is running, otherwise it can loose prime.

I'll check it before too long.

 

[Stan]

Glad to hear it's finally running right. Sorry to hear about the issues with the repair shop.