MEP-8xx wet stack info

Daybreak

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Howdy,

MEP-802A/803A wet stack information.
sample MEP-802A wet stacking
MEP-802A slobber.jpg

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.

Any buyer of a generator should prepare to put a hard load on the unit. After going through and preparing the unit to run. You will want to get it started and loaded. Start with a small load and gradually build. Remember the convenience outlets are only 10 amps. Your unit will thank you by running better too.
View attachment PS MAG. Wet Stacking.pdf
 

TNriverjet

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Mine has improve significantly with running it under a load. I started with an old electric range and logged about 4-6 hours on 3 different weekends to exercise the unit. It's nice as you can vary the load with different sized burners. I also set one burner on "medium" so it would cycle on/off to exercise the governor. It always has some exhaust visible when first starting or after warmed under 90% plus load. The longer it runs the better it gets. I exercised hooked up to the house this past weekend. All lights and appliances AND my daughter was drying clothes in an electric dryer.
 

Daybreak

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Howdy,

Run your generator with a good load.

Remember, the convenience receptacle is only rated at 10 amps. The fuse reset for it is right behind the front panel.
 

Daybreak

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Howdy,
A wet-stacked generator can be cleaned up. Some times a removal of the muffler and exhaust manifold is needed to clean out the wet stack goo. I would suggest a good hard load for all units.
 

DieselAddict

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If it won't pull a full load run it as high a load as it can while maintaining RPM. If its wetstacked it will smoke a lot. Once the smoke clears add load till it stumbles then back it down a bit. Repeat this pattern till it will handle a full load.

Don't forget to let it cool under light load before shutting it down.
 

CallMeColt

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Any tips besides load to help with wet stacking? On trucks, generally a higher RPM helps but on a generator, that really isn't an issue. Asking because I used mine at my off-grid place & during the night, the A/C units don't run hard as the air temperature isn't as high & almost no load is on the unit for probably 45 minuets of every hour. Not really running it more than 25% (according to gauge that I'm not 100% sure is accurate) when bot window units & fan are on anyways. Might get a refrigerator or something for out there to also keep some load on it more often.
 

Zed254

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Buy a used electric stove for your off grid compound. They make a nice load bank for these generators. Cooking a pizza or baking some cookies each time you are there will help clean up any wet stacking in your generator.
 

CallMeColt

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Was thinking of getting an electric cook top & toaster oven for out there, but they won't be on all night. I'd need something throughout the night to keep a decent load on the generator. I tow it out there & can run it on the house for a few hours every month or so to really clean it up good.

Anyone have an idea of how much load keeps this from happening?
 

justacitizen

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Was thinking of getting an electric cook top & toaster oven for out there, but they won't be on all night. I'd need something throughout the night to keep a decent load on the generator. I tow it out there & can run it on the house for a few hours every month or so to really clean it up good.

Anyone have an idea of how much load keeps this from happening?
you could start a battery bank with an inverter and use the excess power generated by your generator to charge the batteries during the day and just use the battery bank at night. it is called a hybrid system and would save much fuel. you can add PV or wind to make the genny run less too.
y
 

CallMeColt

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A setup like that isn't cost effective for my use. I did wire in a small inverter charger with my electrical... Used an RV panel. I have 12 volt lights hooked up along with some small radio chargers to the 12 volt side for when the generator isn't needed in the winter. Of course I'd love a nice battery bank, inverter, etc.! But for the 3 days a month average I'm there, no need. Unless you have extra that I can have. :p
 

jamawieb

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Was thinking of getting an electric cook top & toaster oven for out there, but they won't be on all night. I'd need something throughout the night to keep a decent load on the generator. I tow it out there & can run it on the house for a few hours every month or so to really clean it up good.

Anyone have an idea of how much load keeps this from happening?
IMO your putting to much concern on the wet stacking. Run it as usual, then once every 2-3 months put a hard load on it to clear it up. I have a couple of people that run the sets at 25% or below and then they put a hard load on it to clear it up. I have one guy that has logged over 12,000 hours running 24/7 at 25% on a 802a, he does put a large load on it every 6 months to clear it up.
 

Light in the Dark

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Even though you are in Texas... get a small space heater. You can easily draw 900-5kw with one, depending on style and size. Just plug it in and set it to run while you sleep.
 

CallMeColt

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IMO your putting to much concern on the wet stacking. Run it as usual, then once every 2-3 months put a hard load on it to clear it up. I have a couple of people that run the sets at 25% or below and then they put a hard load on it to clear it up. I have one guy that has logged over 12,000 hours running 24/7 at 25% on a 802a, he does put a large load on it every 6 months to clear it up.
I won't worry as much then as I can easily hook up the house & run it hard for a few hours to clean it up. My main concern is the 0% load for a lot of time overnight.
 

Chrispyny

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i thought i’d tell a quick story. This early/mid summer in the late afternoon, we lost power and internet when a storm rolled thru and a pine tree fell on power, which then pushed power into cable on the pole, a 1/5th of a mile down the road from my house.

It was into the warm season and i can't sleep unless it’s chilly, so we had the ductless minisplits on in the house. When we lost power i fired up the 802 and eventually we went to bed. I woke up at 530 in the am and turned the genset off when i noticed street lights were just turning off. The 802 ran all night under light load. The minisplits are VERY efficient and didn’t draw much of any current.

That morning i noticed the tell tail signs of wet stacking. The slick sooty residue of unburnt diesel was creeping out at the muffler to manifold flange. I knew i’d wet stacked it and would need to run it hot to clean it out.

(As a side note, i bought this genset non-reset with 22 hrs on it from Fort Drum a couple years ago. At that point i changed the oil to rotella full synthetic, a mistake on my part so early in the engines life. Yesterday before it’s excersise, at 44 hours, i changed the oil to John Deere Break-In oil per Daybreaks suggestion.)

So i waited until yesteray, a cool and chilly early fall day to excersise the genset. I have a 5,000 watt, 240v electric heater i wired up in the garage which serves as my excersiser. I ran the genset for almost 4 hrs with the heater on, and occasionally turning on 800 watts of flourecent lights in the garage, and allowing things in the house to cycle on and off like the fridge, and a box fan moving warm air into the house from the garage, taking advantage of the heat to warm the house.

After warming up for 5 minutes, i placed an increasing load on the genset from the heater over a span of 10 minutes. The switch on the heater allows for 3, 4, then 5k watt settings. At start up, and under load, the genset smoked a white/blue smoke for almost 30min. It got progressively better until it was clear.

Another thing i noticed was after some time is that i had to adjust the governor down a tad, as once the genset was hot and cleaned out, it took less effort to stay at approx. 59.3-59.5 hz under a 5k watt load. It also ran much smoother as well.

The garage lights are on two switches. Each switch turns on 2 light fixtures in the garage. Four 50 watt T5HO bulbs per fixture, for a total of 400 watts per switch, or 800 watts of flourecent lights in total. They are driven by electronic ballasts so the power factor is close to 1, which can be compared to resistive loads. Basically the genset ran for periods of time at 5,800 watts, while a box fan ran and a fridge cycled on and off, and it did so comfortably.

I had free time so i figured i’d share. It really goes to show that it is critical for the 80x gensets health to give it a good occassional workout. Now i just have to clean off the soot at the manifold/muffler and the genset is ready for the winter.

Thanks all for such an awesome forum, and everyones input which helps me leep my genset running like a top.
 
Last edited:

Bmxenbrett

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Wet stacking and diesel soot are not the same. With your engine at 44hrs its not even broken in so it may be wetstacking with a small load due to that.

I have a 802 that ran a small 4,800btu on/off one night. Looked the same as when i went to bed. Its got 240hrs.
 
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