MEP 803A Wet Stacking

[JCamp]

I’m using home heating oil #2 to fuel my MEP803 A. I’m adding lubricity additive. I have enough fuel to run the genset day and night, but I’m worried about wet stacking. Is there a rule of thumb around how much load should be on generator to prevent wet stacking? For example, should I run it at minimum 20 or 25% load at night when there isn’t much draw? Or, should I make a point of running it harder by turning on an oven, electric heater, air, conditioner,…

It will be running two standard refrigerators, one below the counter freezer, well pump, and the the usual other things seem pretty low draw.

I’m asking because my mother has medical equipment that should run all night, very low draw but nonetheless it needs to be run consistently. One option is getting a rechargeable battery unit that will supply 120 V to run that equipment, and just turning the generator off at night. However, that wouldn’t run my refrigerators, freezers, and water pump. Any comments or suggestions?

 

[Scoobyshep]

Usually 80%

Here's the thing it won't wetstack over night. Periodically load it up to rated capacity and run it for a couple of hours. That should keep the wet stacking away

 

[rickf]

Do these sets really wet stack? I would understand it happening if they were running at idle all day but running at rated 1800 rpm would in itself prevent wet stacking.

 

[2Pbfeet]

I’m using home heating oil #2 to fuel my MEP803 A. I’m adding lubricity additive. I have enough fuel to run the genset day and night, but I’m worried about wet stacking. Is there a rule of thumb around how much load should be on generator to prevent wet stacking? For example, should I run it at minimum 20 or 25% load at night when there isn’t much draw? Or, should I make a point of running it harder by turning on an oven, electric heater, air, conditioner,…

It will be running two standard refrigerators, one below the counter freezer, well pump, and the the usual other things seem pretty low draw.

I’m asking because my mother has medical equipment that should run all night, very low draw but nonetheless it needs to be run consistently. One option is getting a rechargeable battery unit that will supply 120 V to run that equipment, and just turning the generator off at night. However, that wouldn’t run my refrigerators, freezers, and water pump. Any comments or suggestions?

I would not sweat the wet stacking as long as you periodically load the generator. That said, I do not think it is a great idea to run a diesel with little to no load, and I would look at batteries to provide low power support.

Is this off-grid, or for emergency use?

If it were me, and it is emergency use, I would get batteries for your mother's medical equipment, and I would let everything else be off overnight.

Off-grid would be best served household batteries in my opinion.

All the best,

2Pbfeet

 

[FarmingSmallKubota]

If your already on Generator why not supplement the heat with a small space heater

 

[Scoobyshep]

Do these sets really wet stack? I would understand it happening if they were running at idle all day but running at rated 1800 rpm would in itself prevent wet stacking.

Yes because it's not working hard enough to produce enough exhaust heat.

But again it's not something that happens overnight do a good load banking once in awhile and you're good to go

 

[Ray70]

Yup, they sure can wet stack!
I've had a handful of 803's carboned up to the point that the valves won't close all the way, Lister Petter even sells a gasket kit called a Decarboning kit which includes everything needed to yank the head off and clean it.
Granted, these were extreme cases where they were too far gone to simply load up and clear out, but a testimony to what can eventually happen if you never load the machine up for hundreds of hours.

 

[DieselAddict]

I had one come through here a couple of months ago that had around 300 hours on it. It smoked and wouldn't take a full load. It peaked out around 8kw. I loaded it up as much as it could hold and let it run. As the exhaust heated up it started spitting out chunks of carbon and the smoke reduced. Once the smoke was mostly gone, I added more load. Wash-rinse-repeat. Once I had it up to 12k of load with only the normal amount of smoke it would show at that level, I knew we were done.

I expect this unit was NEVER run with any significant load on it. It took about 3hrs of running to get it cleared up.

My recipe would look like this - if its reasonable for you and assuming you are running around the clock, get a good load on it for around an hour a day and you will never have a problem with it. A good load as stated above is around 8kw. That is enough to burn out any gunk that is starting to accumulate.

 

[CallMeColt]

Before you go to sleep, run it hard for 20 minuets. When you wake up, run it hard again for 20 minuets. Turning the dryer on will do the trick. I used to do something similar with my MEP-802 at my off grid place when running for days at a time. Load it up with the heater for a bit. 23hrs out of the day, it was 10-20%, sometimes none if the A/C would cycle off.

 

[CallMeColt]

I had one come through here a couple of months ago that had around 300 hours on it. It smoked and wouldn't take a full load. It peaked out around 8kw. I loaded it up as much as it could hold and let it run. As the exhaust heated up it started spitting out chunks of carbon and the smoke reduced. Once the smoke was mostly gone, I added more load. Wash-rinse-repeat. Once I had it up to 12k of load with only the normal amount of smoke it would show at that level, I knew we were done.

I expect this unit was NEVER run with any significant load on it. It took about 3hrs of running to get it cleared up.

My recipe would look like this - if its reasonable for you and assuming you are running around the clock, get a good load on it for around an hour a day and you will never have a problem with it. A good load as stated above is around 8kw. That is enough to burn out any gunk that is starting to accumulate.

Not to derail the post, but I have a unit that I have almost given up on that spits chunks at 50% and will slowly chug & die at 100%. I never let it go for an extended period, only like 20 minuets. Almost 5,000hrs but otherwise looks healthy. Should I just send it at 50-60% for an hour and see if it clears up?

 

[Ray70]

Most folks say to step up the load sequentially, allowing enough time between steps for the smoke to clear out. You could start at 50% for an hour, if it clears at 50% step it up to 75% and leave it until it clears again, then step it up and see if she will handle 100%
If you still have no luck at 100% try taking the muffler off and retest. at 5000 hours if its severely wet stacked the issue could be in the head and not the exhaust. A carbon choked head is much harder to clear out by just running it hard, you may need to remove the exhaust manifold and scrape out the exhaust ports manually.

 

[CallMeColt]

Most folks say to step up the load sequentially, allowing enough time between steps for the smoke to clear out. You could start at 50% for an hour, if it clears at 50% step it up to 75% and leave it until it clears again, then step it up and see if she will handle 100%
If you still have no luck at 100% try taking the muffler off and retest. at 5000 hours if its severely wet stacked the issue could be in the head and not the exhaust. A carbon choked head is much harder to clear out by just running it hard, you may need to remove the exhaust manifold and scrape out the exhaust ports manually.

I let it soak with ATF in both the tops of the cylinders & more. It cleaned a lot out. But thinking one of the valves is not letting a cylinder fire right. Probably all chunked up. Exhaust gets into the crank case. All making sense now...

 

[DieselAddict]

Not to derail the post, but I have a unit that I have almost given up on that spits chunks at 50% and will slowly chug & die at 100%. I never let it go for an extended period, only like 20 minuets. Almost 5,000hrs but otherwise looks healthy. Should I just send it at 50-60% for an hour and see if it clears up?

Yep, load it as much as it can hold without chugging down and wait. If it’s spitting out chunks then it’s clearing itself. Bump up the load as it can take more. It should recover.

The worst one I ever got was an 802 that couldn’t even hold 2kw. After a few hours of “therapy” it would take 6.5kw.

 

[DieselAddict]

I let it soak with ATF in both the tops of the cylinders & more. It cleaned a lot out. But thinking one of the valves is not letting a cylinder fire right. Probably all chunked up. Exhaust gets into the crank case. All making sense now...

Yea, if it’s not running in all cylinders, you need to resolve that first. If you are taking everything apart to unstick valves, you can put the muffler in a smoldering fire and cook out the junk. Will give a good head start on things when you put it back together.

 

[CallMeColt]

Yea, if it’s not running in all cylinders, you need to resolve that first. If you are taking everything apart to unstick valves, you can put the muffler in a smoldering fire and cook out the junk. Will give a good head start on things when you put it back together.

I was a little worried I would cause more damage or something as with all of them, I hadn't seen one that stacked up yet! It didn't show any of the other signs of it like the ooz at the muffle gasket, etc.

 

[Ray70]

I let it soak with ATF in both the tops of the cylinders & more. It cleaned a lot out. But thinking one of the valves is not letting a cylinder fire right. Probably all chunked up. Exhaust gets into the crank case. All making sense now...

I've had several 803's with low hours that were caked up with carbon to the point that none of the 4 cylinders had compression due to the valves being held off their seats by carbon buildup.

 

[Guyfang]

Most folks say to step up the load sequentially, allowing enough time between steps for the smoke to clear out. You could start at 50% for an hour, if it clears at 50% step it up to 75% and leave it until it clears again, then step it up and see if she will handle 100%
If you still have no luck at 100% try taking the muffler off and retest. at 5000 hours if its severely wet stacked the issue could be in the head and not the exhaust. A carbon choked head is much harder to clear out by just running it hard, you may need to remove the exhaust manifold and scrape out the exhaust ports manually.

This is the proper way to do it.