New to me PU798A (Mep-803a on a LTT-TQG high mobility)

New to me PU-798A (MEP-803A on a LTT-TQG high mobility)

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New to me PU-798A (MEP-803A on a LTT-TQG high mobility)

Howdy,
I now own a MEP-803a on a LTT-TQG high mobility trailer. The combo is known as a PU-798A High Mobility. I do not understand how some items get sold, and some get reset.
2007 Fermont MEP-803A 10kw Tactical Quiet generator
2006 Silver Eagle Light Tactical Trailer Heavy Genset style aluminum trailer. (similar to a M1102 Heavy)

Conclusion;
The entire unit is very clean. The only thing which is damaged is the rear balancing support leg. At some point in its life it was picked up with a forklift and the flattened out the bracket, making it unusable. It has all the manuals still in plastic seals. The oil filter had a date of 3/12. The total runtime is low 300 hours. The unit had 2 Optima Red batteries. (1 Model 34 8002-002 and a Model 34/78 8004-003) The report stated it would not start without a jump and would not start after being shutdown. It also stated that it would not start properly and had to bypass the electric fuel switch. After getting home and using a BatteryMINDer Model 12248 to slow AGM charge each dead Optima battery, they came back to life. While the batteries were charging. I long drained all fluids from the unit over night. After the fuel tank was drained, I then flushed another 2 gallons at a time of fuel in the tank and sloshed it around. I did this 4 times. I took out the fueling extension, and cleaned the screen on it. I now have 8 gallons of diesel to lite up my fire pit a few times. After draining the radiator, I realized I got about 4 quarts out. No wonder it gurgled on the report.
I use John Deere products here already, so I used Deere Plus-50 II 15/40 oil, and Deere Cool-Gard II coolant. I hit up my local NAPA store and got NAPA Gold Fuel Filter Cartridge 3348, NAPA Gold Fuel/Water Spin-on filter 3472, NAPA Gold Oil Filter 1374. I wanted to clean up the fuel system too. I hit up my local Southern States for some 47 cetane premium diesel. I also added some Lucas fuel injector cleaner (double dose)
The next day, all fluids are well drained. I put on all the filters, sloshed some more diesel in the tank, and stirred it around. Finally filled the tank with diesel. Filled the radiator and overflow coolant bottle. Filled the oil. Hooked up the fully charged Optima red top batteries. Primed and bled the fuel system. Reviewed start-up procedures, and the unit started in the first 4 seconds if that. Set the frequency and voltage. Let it run a few minutes and shut it down. Checked the oil level, and then restarted the unit. The generator was not running correctly. I removed the exhaust system and cleaned out the exhaust manifold. The engine could barely breath due to the carbon goo build-up. After getting it all back together I kept a pretty steady load between 8kw to 12 kw. The unit started to run and sound better the longer it ran. I did this for about 1.5 hours. Very happy with generator.

I happen to get lucky with a unit which runs.

Congrats on an obviously good generator. You are to be commended for your thorough, well thought out prep for initial start up. You can't beat these military generators.

Howdy,
OK, If my unit is the standard example of genset being sold.... you really need to do a 1-2 hour load test to clean out the pipes. I removed my muffler, and removed the exhaust manifold. I manually scrapped out the pathways in the head. Cleaned out the muffler as best as I could. Obviously the generator was run very lightly loaded in its prior life. When I pulled the exhaust manifold off, it was almost totally plugged with thick gooey carbon. I soaked the manifold overnight and then pressure washed it. Put it all back. Hooked it all up, started it up, and carbon flecks flew all over, ran a few minutes and then started loading it up. Got to 50% for about 15 minutes and the smoke just kept coming. Brought it up to 100% and it just kept smoking and black liquid dripping. After about 15 minutes here, the smoking was clearing up. I brought it up to 120% load, and it smoked some, but kept humming along. Stayed at 120% for 15 minutes, and then backed down to 75% load, now the exhaust is starting to clear up. Stayed here 30 minutes, went back to 120% for 15 minutes, sound and exhaust really looking much better. backed down to 75% 15 minutes, then down to 5% for a while. I then started turn things on and bouncing around with loads, the sound is much better, and now just a hint of smoke when a new load is added. I went up 25% at a time up to 125%. The whole generator is running smooth and not smoking like it first was. I gradually reduced everything back to 5%, opened the ac interrupter, waited a few minutes and then shut down. The MEP-803a is a very solid 10kw prime generator with a surge rating which I do not know the exact range, but it just kept running.

Halfway through at 120% load
https://youtu.be/FnWCyex-eGM

Howdy,
I have put an additional 1 1/2 hours of loaded time on the unit. It is running and sounding much better. All the fuel return lines are weeping diesel. I will be replacing all those lines shortly.

I heard wet stacking was a common problem with those tactical quiet generators. I don't know if it had to do with the generator itself or the way they were run with light loads.

Augi

Augi said:

I heard wet stacking was a common problem with those tactical quiet generators. I don't know if it had to do with the generator itself or the way they were run with light loads.

Augi

Click to expand...

Howdy,
I think they might have run the generator and only used the 2 little convenience outlets. At least until the black liquid starting running out of the exhaust manifold and muffler. Then they sold it

Keep an eye on your lube oil level as well.

I can't seem to find it again but I read somewhere that stated less than 20, 25 or 30% load would lead to wet stacking. I think it was 30%.

I suppose that lighter winter blend would do it less than summer blend?
Also curious if any additive would help or if any fuel adjustments might help?

It did say that running it hard would burn it off but I guess not if it goes on too long.

http://www.genpowerproducts.com/files/Wet-Stacking-Prevention.pdf

I found it today in the operator manual. It stated under 25% of rated load can lead to wet staking on the MEP-8xx series. Hope that actually means 2500w and not 25% on the gauge because I think it might take over 4500w to get 25% on the gauge.

The gauge lies. Divide it by 0.8 if you are running a resistive load. You'll be fine.

By the book, 25% should be 1250 watts on a 5kw genset. That sounds reasonable to me to create enough load to keep heat building and pressure high. I don't think the manual would say to run at 25% based on loading it over it's rated running, when the max loading could vary.
You could put in a sensing circuit that switches on a 1300 watt device when normal load drops too low.

I agree, I was just questioning the videos I have seen where the 803's dont appear to really register a load 2500w at 25%. Always seems like it takes more watts than that. I will rewatch some of the videos.

Wish I knew how to make a sensing circuit. What would that cost in parts?

Making a sensing circuit isn't so straight forward. You have to measure the current waveform and the voltage waveform then perform some math to get to apparent power.

Your application doesn't require that level of sophistication. Just know that the load meter is assuming a 0.8 power factor. If you are applying a resistive load which has a power factor of 1 you just take the meter reading and divide by 0.8 to get the apparent power.

If you want to have some fun and experiment with building something to measure power factor take a look at this - http://www.syscompdesign.com/assets/Images/AppNotes/power-factor-measurement.pdf

There is a decent explanation there about what is going on.

If you want to maintain a minimum load on the generator for testing or whatever you just need an adjustable current switch and a power relay for the load switching.

http://www.grainger.com/product/FUNCTIONAL-DEVICES-INC-RIB-Current-Sensor-21AJ49?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/21AJ49_AS01?$smthumb$

I was thinking of current transformers regulated by a zener diode, driving a relay that opens as current increases.

The current transformer generates a small voltage based on the current flowing through the output lines (L1 & L3 for a household). The zener diode will pass no current until it crosses a certain voltage (let's say 5v).

The relay throws a contactor that disengages your 2500 watt dummy load. The relay does nothing until current flowing on L1 or L3 cross over a threshold. It would take some experimentation and adjustment to find the values for the current transformers.

Another attempt to explain;
As work load increases, voltage on the current transformers (CT) increase. When load is low, CT voltage is low.
Until CT voltage reaches 5v, it's completely cut off from the relay by the Zener diode.
When not powered, the relay conducts power from L1/L3 to your 2500w load. Once the relay is powered, it breaks that connection, dropping the 2500w load, since the work load has now risen to the minimum power-output threshold.
The connection to the 2500w load should come from the output side of the genset contactor to provide some overload protection, but before the current transformers. Because of this, you also can't use the built-in current transformers, as they would never be able to tell you if your output load or the dummy load is drawing power, therefore provide no way to automatically drop the dummy load. There are more details to consider, but I doubt anyone will go this route based just on this post, without doing significant research themselves first.

PU-798A all cleaned up

Howdy,
OK, after pressure washing all the tape, stickers, writing etc... I have gotten it cleaned up. Its really looking good.

It sure is looking good! Good score on picking up that unit and going through it properly.

New to me PU-798A (Mep-803a on a LTT-TQG high mobility)
A Fermont MEP-803A 10kw TQG mounted on a 1 1/2 ton Silver Eagle LTT-TQG. Trailer is similar to the M1102 but generator configuration. The trailer is all aluminum. Mine is using HMMWV tires with run-flats.