MEP-803A - Black smoke under load

[mesias]

I'm splitting this topic from the THIS thread. I think it's worth covering separately the black smoke from my genset while load testing it. HERE is a video of the test.

I already received great feedback:

Usually once you get them cleared out you should have virtually no visible smoke until pretty close to or sometimes even above 100%.

You will vary slightly from 1 machine to the next, but in general you should get pretty close to 100% load with not much smoke. If you see smoke coming on way too early you either still have carbon buildup or 1 of the metering pumps may be adjusted incorrectly.

The best way to identify a mis-adjusted pump is to use an IR thermometer to compare EGT between cylinders or best way is to remove the exhaust manifold and you will see the offending cylinder right away. Although removing the manifold at this point may be a bit of work in your instance.

I looked at the video, It's a bit hard to tell but the smoke looks black.
Since you said 1 cylinder has some tar coming out of it my guess is either 1 injection pump is not metering properly or an injector isn't firing right.

I don't mind removing the hood and the cover, I just used a few bolts to keep it in place. I checked the temperature between cylinders on the outside of the exhaust ports and they are not the same, they are close but not in the same range. On top of it, the reading changes by moving the IR dot by just a 16th of an inch. What would be the most accurate way of checking this? What should I look for after removing the exhaust manifold?

I assume adjusting the IP would take rotating them to allow less or more fuel. If that's the case, clockwise increases the flow, right?

 

[nextalcupfan]

Here is my 803a, it doesn't start blowing black smoke untill it goes over 100% load. From what I've read on here that seems pretty standard.

I recommend checking temps in the spots under the exhaust manifold. (0:37-0:54 in the vid)

I'm not sure what the max variance should be but mine was about 4F from the hottest to coldest cylinder.
This was under a varying load of 25%-60%. (Unit was running my house)

I plan on getting more temp data when I put it on my load bank.

 

[mesias]

My unit runs a lot hotter than that... I'll try doing another load test tomorrow and I'll record the temps again.
Good idea embedding the video... I'll edit the initial post.

 

[Ray70]

If you end up pulling off the manifold, look into each of the 4 exhaust ports and see if any look wet or with more carbon buildup than the others. Then start the machine and load it up. Look at the 4 ports and see which one is causing the smoke. ( use a flashlight if necessary to highlight the smoke ) The offending cylinder may have either a dirty ( leaking injector ) or the metering pump may just be out of adjustment. If that cylinder is running much hotter than the rest try turning the metering pump a little bit counter clockwise.
If that doesn't help it may be time to look at the injector more closely.

 

[k9medic]

Here is my 803a, it doesn't start blowing black smoke untill it goes over 100% load. From what I've read on here that seems pretty standard.

I recommend checking temps in the spots under the exhaust manifold. (0:37-0:54 in the vid)

I'm not sure what the max variance should be but mine was about 4F from the hottest to coldest cylinder.
This was under a varying load of 25%-60%. (Unit was running my house)

I plan on getting more temp data when I put it on my load bank.

At the risk of sounding foolish - what is the black oozing stuff at the beginning of the video? I have that on all of my exhaust areas.

 

[nextalcupfan]

At the risk of sounding foolish - what is the black oozing stuff at the beginning of the video? I have that on all of my exhaust areas.

Wet stacking.
I'm not 100% sure what it's made of exactly, excess fuel mixed with soot?

 

[Light in the Dark]

Those are unburned hydrocarbons and combustion residue. When a machine is running under sufficient load (thus sufficient EGTs), those are burned off and exit the machine. When the exhaust temps are too cool, or the machine is not adjusted properly, it builds and so does the chance for top end problems.

Letting a machine run at capacity for a few hours normally clears up any lingering wet stack concerns.

 

[Daybreak]

Howdy,

MEP-8xx wet stack info

Howdy, MEP-802A/803A wet stack information. sample MEP-802A wet stacking A lot of the military units are run lightly loaded, or simply not loaded. They might even be started and run for a hour or two every other month. Whatever the situation, the above picture shows a case of wet stacking...

www.steelsoldiers.com

Wet stacking hurts the over all operation. This is why it is important to run your generator loaded to clean this issue up. If it is not cleaned up, it will keep building and clogged the exhaust and muffler. This is also why some people say their generator can not go higher than 60% load or something. You load bank the generator and keep raising the load. A good hard 100% for 3-4 hours will clean it out.

 

[Mr4btTahoe]

Maybe a stupid question... but basics...

Is the air filter new / clean? If a diesel can't get the air it needs, it will smoke.

 

[mesias]

I adjusted today a couple of IPs and I think it improved a bit. Based on the temp readings while on load I need to adjust more the second IP. I tried measuring the EGT at the bottom of the exhaust manifold and at the top of the exhaust port. Here are the readings I could gather (bottom manifold/top port):

1. 441/365
2. 479/416
3. 465/370
4. 459/360

Here is a video of the temps:

Here is a view of the exhaust gases after the adjustment:

The air filter is clean, not new but clean.

Thanks!

 

[Daybreak]

Howdy,
That's not black smoke. That's a diesel engine working.
When someone says black smoke. That means it putting out black smoke. Really black smoke.
Take a look at a few different video's of MEPS being loaded here.

Acquired a Military surplus load bank

Howdy, Essex Electro Engineers A427 Load Bank It was made around 1970. 0-33kw coverage, single and 3 phase. 3kw, 6kw, 9kw, 12kw switches in any combo, and a 0-3kw variable turn knob. It really makes thing easier to keep a generator in shape. The MEP-803A can really pull some power. It...

www.steelsoldiers.com

 

[mesias]

Hi there,
I thought that even under max load the diesel engine should not have visible smoke. Bursts of black smoke are OK when a load is added. But based on Daybreak's video my MEP is working just fine. This is the type of reference hard to find in forums an TMs, only real life experiences provides it.

Thank you for your feedback.

 

[frank8003]

It will be just ducky, run Her.
Run that puppy as it was designed to do at 85% + + load.
You don't really think that the supposed end customers, our guys, wouldn't run the poop out of them?
They were built to spec to RUN
We don't care about smoke unless it gives our position away...........
Not to worrry................
Wish I had one.