To Purge or Not to Purge | 855 Cummins

[Zoidsfan77]

Greetings gentlemen!

My new to me M814 seems to be low on power. This is my first MV, so maybe they really are this sluggish. I cannot quantify it well in words, but 0-55mph (at full power, unloaded, on stock 11.00x20 tires and on level ground) takes well over a minute. It drives like it is loaded.
Additionally, it has some noticeable diesel knock (especially at idle), and leaves a haze of smoke, even at a steady 40 MPH.

Bearing this in mind, here is my situation:
I installed a spin-on fuel filter kit, and it works great. I feel much better with a 6 micron secondary filter on there. The kit came with a new fuel hose from the filter housings to the pump.
(P.S. I got my filter kit from cimarron@minister.com. The kit is great, comes with fuel line, fittings, filter heads, two filters. It is a bolt on deal. He made sure everything was right.)
The line I removed (which I believe to be original to the motor) was lined with a fairly thick layer of black varnish. I fear my entire fuel system is coated in this stuff.
It is probably safe to say some, if not all of my injectors are partially clogged, or in some way affected by the sludge.

My dirty fuel line:


So, I could try one of the many fuel system cleaner products available (seafoam, Diesel Klean, Lucus, etc.). I have heard that there is some risk to doing this. I would really prefer not to loosen up some hideous blockage, upsetting the spray pattern on an injector, potentially resulting in the meltdown of a cylinder.


I want to know what you all think? Should I try some sort of fuel system cleaner? If so, any recommendations? In tank or in filter "purge" style?
Am I just being paranoid / overly-cautious?

I apologize if this has been discussed in detail here before. If so, I was unable to locate the thread.
Diesel fuel cleaners and additives are a popular topic on diesel pickup forums. I have never heard of a cylinder melt-down after fuel system cleaner treatment on these forums, but their diesels are much different than our 855 Cummins. I have read at least one case of cylinder melt-down on an 855 Cummins here on this forum, where the cause was an obstructed injector. This was not due to any fuel system cleaner though.

Thoughts?

 

[gimpyrobb]

Another member bought an 819 with the nhc250 and ran rough! He put 3 or 4 bottles of seafoam in the tank and I was really surprised how well it helped the truck run smoother and the hunting idle went away. I was sold on it from then on.

 

[red]

The fuel system on these older diesels are more tolerant of crap being in them than newer common rail diesels. That being said if it's smoking/hazing constantly right now you have at least 1 injector sticking.

Start off by installing a EGT probe/gauge, this will help you find out quickly if there is a problem. Temps will increase if a injector sticks completely open. Let's say at idle it's normally at 250 degrees and now it's maintaining 400 degrees at idle then it's having injector issues.

After the EGT gauge is setup run the cleaner. I run either B12 or Seafoam (it's very similar stuff) because it works and is cheap.

 

[WillWagner]

The injectors on the NHC cannot stick open. They aren't pintle style, and are manually activated/operated by the camshaft. Cummins makes a product that works VERY well. It is normally used pre overhead set to remove carbon from the metering and tip area of the injector plunger so when the injector is set, carbon isn't forced into the cup causing a miss or low power. I have personally seen this product add 50 hp to an engine w/o a tune up. The black stuff you pictured is kinda normal for something that has been in service a long time.

https://www.cumminsfiltration.com/sites/default/files/MB10106.pdf

It ain't cheap.

You will know if the engine is missing on acceleration, it is very noticable, so if it isn't rough feeling on acel, there is no miss. People think setting to overhead on these is hard, alot of people do it wrong. It is quite possible that the PO, most likely a .gov temp employee set the overhaed wrong. Common symptom of an overhed set incorrectly, slow acceleration, steady haze of grey black smoke going down the road, white smoke at idle.

If it were me, i'd check for full throttle travel then do the injector douche and set the overhead. There is a stickie that will walk you through the tune up process.

 

[Zoidsfan77]

Thank you all for the replies and wisdom!

I don't think my truck is missing. It idles rough, and shakes quite a bit, but smooths out as the RPMs increase above about 800. Idle also hunts for a short time when throttle is released.
I'm planning on doing the overhead when I get some OK weather (supposed to rain/sleet all this week I think).
I have an engine barring tool, dial inch-pound torque wrench, and a set of feeler gauges.
There is a Cummins dealer not too far from here, I will see if they have the fleetguard stuff.
I ordered an EGT gauge, as I wanted one anyway.

I will update as I go.

 

[swbradley1]

Set the idle RPM up about 50 and it will smooth out. My 813 rattles so bad that Gimpy and I can't use the mirrors to back the thing.

Flat out on level ground my truck will do 2,150 RPM with my foot to the floor.

Tip for you, get a spare throttle return spring. Towing a M923 without one is a b1tch, ask Gimpy.

 

[WillWagner]

It takes a "special" tool to raise the idle. It is done through the gov. end of the pump

 

[ke5eua]

It takes a "special" tool to raise the idle. It is done through the gov. end of the pump

Special tool is only required if you wish to adjust the screw with the engine running.


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[WillWagner]

True, but how times does one want to make a stinkin' diesel fuel mess. Once is good for me

 

[ke5eua]

True, but how times does one want to make a stinkin' diesel fuel mess. Once is good for me

I'm cheap, lol


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[Zoidsfan77]

A quick update my friends!

I have been running the Fleetguard Injector Cleaner for a little over a week.
Although I only get time to drive my truck an hour or two every other day or so, it seems to have made some difference.
I can't say I have any more power, and she still smokes just as before, but it runs a little smoother and no longer surges at idle.

I am hoping to do the overhead this weekend or next, weather depending.

I will write back with my results then.

 

[Nomadic]

I'd do a compression check to see of you have a few cylinders down. Seems awfully slow, but I've never driven one.

 

[ke5eua]

A quick update my friends!

I have been running the Fleetguard Injector Cleaner for a little over a week.
Although I only get time to drive my truck an hour or two every other day or so, it seems to have made some difference.
I can't say I have any more power, and she still smokes just as before, but it runs a little smoother and no longer surges at idle.

I am hoping to do the overhead this weekend or next, weather depending.

I will write back with my results then.

The dual fuel line mod will help with the surge at idle a little.


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[Zoidsfan77]

Update:

I removed the rocker covers, and began the procedure to adjust overhead. I am going off the advice here: http://www.steelsoldiers.com/showthread.php?73256-Nhc250-valve-injector-overhead-adjusting Post #8.
I hadn't even finished my first injector, on cylinder 1, when my flathead bit came out of my 1/4" socket, falling into the engine down between the pushrods.
After a minute or two of being frozen in shock and horror, I grabbed a flashlight and peered down there. I was able to see the cam followers/rollers, but no bit. It had sounded like it made it down to the oil pan.
Tomorrow I am going to drain the oil and see if I can get it out of there. I have a few cheap endoscopes, which I will likely need, as well as some stick magnets.
If I cannot get it out around the filter screen, I have a powerful (3" x 1/2") neodymium magnet, I may be able to use it to get the bit to walk around the perimeter of the pan and hopefully where I need it to go.

Needless to say, I am very sad.

 

[WillWagner]

Oops. If if went into the pan, you are ok. No issues with that, seen all kinds of things there, but, if the bit went between the cam follower and the housing, the assembly the followers are in, THAT is an issue. If you run it like that and the tool is between the two, you will break the box. For anyone reading this...DO NOT USE A SCREWDRIVER THAT HAS CHANGEABLE/MAGNETIC BIT ENDS...Guess that tidbit of info needs to be in the sticky? If you have a thin mirror that extends you can look behind/on top of the followers to see if the tool is there.

 

[Zoidsfan77]

Good news friends!

I have retrieved the fallen tool. It was not as difficult as I first thought.
For anyone else who makes the same mistake, here is what I did.

I drained the oil.
I have a 3" x .5" neodymium magnet puck. It is very powerful, and if handled incorrectly could probably break your fingers.
Carefully, as to not let the magnet get stuck to any of the nearby ferrous metals, I placed it against the oil pan, near the front of the engine.
Fortunately, the oil pan is aluminum, so the magnet won't stick.
Starting from the front and working back, I swept the magnet over the pan in a slow, back and forth motion.
It wasn't long before I heard a little *click* noise. If I continued to move the magnet, I could hear the object inside following it.
Now, I slowly drag the magnet up the drivers side of the oil pan, listening for the object to verify it is still following, and across towards the rear of the engine.
Once at the rear of the pan, I rounded the corner, and moved down towards the drain plug.
Then, with a *ping* the object flew forth from the hole to be united with the magnet.

The trick is to guide the object away from the obstacles in the pan, the pickup screen being the largest.

Hopefully this helps anybody who suffers a similar fate.

Now, back to the topic at hand.
It is raining out right now, so finishing the overhead probably wont happen today.
Hopefully weather will cooperate in the near future and I can wrap this up. (Only to discover it is worse than before probably, haha!)
Thank you for your patience friends!

 

[dmetalmiki]

Very interesting thread, and another 'tip' learned. Thank you.

 

[gimpyrobb]

Slow and steady wins the race! Take your time and do it right, you will be miles ahead in the end.

 

[red]

Well done on the bit recovery

 

[Zoidsfan77]

Sorry for the delay, been really busy at work.

Finished the the overhead adjustments, and went for a test drive the other day.

On first startup, it was like a volcanic eruption. Enormous grey black smoke cloud, and soot and ash, even a small amount of black liquid.

It cleared though and the engine idled fine.
I drove it about an hour, mostly around town, then returned home. It no longer smokes at idle when warm, and the smoke while under power is certainly reduced, but I do not notice any improvement in power, sadly.
I cannot imagine trying to accelerate with anything less than full throttle. Sometime perhaps I will post a video of a full throttle acceleration. As I said before, 0-50mph at full throttle seems to take over a minute.

In case I did something wrong, here is the procedure I used:

Barred the engine over to VS 1-6.
Cylinder 1's intake and exhaust ports were closed (rockers loose).
Loosened locknut on injector rocker.
Adjusted adjustment screw to 70 in-lbs with a brand new dial-type torque wrench.
Tightened lock nut.
On the same cylinder, I loosened both locknuts on the valve rockers.
Using a set of feeler gauges, I set the intake to .017" and exhaust to .027".
Re-tightened lock nut.
Repeat for all cylinders.

If anyone sees anything wrong with my procedure, please let me know.

As far as next steps, Nomadic recommended doing a compression test. I don't actually see how to do that on this motor without removing injectors.

Speaking of injectors, I wonder if perhaps it would be a good idea to replace them?


Thank you all for sharing your knowledge and wisdom.