newer 803A smokes and bogs down with load ... start with injectors?

newer MEP 803A smokes and bogs down with load ... start with injectors?

Hi new 803A owner here, Not much of a mechanic and I haven't found my problem discussed in the threads so please bear with me ... 175 hours on the machine when purchased in online auction, very clean, I drained then topped off all the fluids including fuel (drained water separator but didn't change the filters yet), it has the crank fuse mod, starts great, smokes very little when cold and no load. Problem is after it is warmed up as I apply load it starts smoking blue smoke, the more load I apply the more it smokes. At 50% load it smokes but holds the load with 2-3 Hz drop in frequency, it will take 50% load for hours but about 75% load smokes turns black, lots of smoke and it bogs down, output falls to near nothing but it hasn't completely died as I remove the load when this happens. After 30 seconds or so after I reduce the load it goes back to smaller amount of blue smoke and producing power OK. Temp runs about 180, oil gauge pressure about 20 (seems low but I haven't tested it apart from the gauge), no fuel in oil as far as I can tell. I have run it for about 4-5 hours with fresh fuel (Howes and LDL additives) and then 2 different kinds of injector cleaner (Stanadyne and LubriMoly). I checked the air filter and intake hoses, all clear. The smoke hasn't gotten any better and it still bogs down at about 70-75% load. I've read the troubleshooting sections of the manuals and read lots of threads. Most things point to maybe having compression checked first then having the injectors cleaned and tested, reset and maybe timing ? I have a farm mechanic who does a lot of diesel work who can do it ... but before I pay him the $ to troubleshoot it am I missing anything first or anything else I should tell him? Many thanks ...

PS ... I think I have an inexpensive "load bank" figured out ... it's just an old electric range, I crack the oven door and point a box fan at it. I haven't maxed it out yet but I think it will get me to at least 100% load and if needed I can add a couple milk house heaters using a spider box to get to 13KW ... I feel better about this than the combo of electricity and water in the water heater element and 55 gal drum set ups ... the stoves are usually free and so far it's working well, FWIW

does the gen have black soot like buildup around the exhaust flange? where the muffler bolts to the manifold? "wet stack" I purchased a 803a about 6 months ago and it only had 300 hours but had wet stack. if so, it take a lot of heat to burn it out. 100% load for at least an hour. I use a bunch of heaters to do my load banking. my gen was now where near as bad as what you describe but after the load bank, it ran noticeably smother and lest smoke at 100% event at 120%..

20 psi oil does seem a bit low? what weight oil you using?

I would start with new fuel filters. This way you will know where you are with them since they are a normal maint item. If you have spin on filters, cut them open and check for anything that doesn't look right. Black slimy stuff normally means algae. Also while filters are off, hold a clean container under them and start the fuel pump and make sure their is good flow and if you see any contamination. Some electric pumps have screen on the intake side. When I got my 802 I had to drain fuel to repair the well nut for the drain. After I drained it, I used white paper towels to wipe the bottom of the tank, mine was all nice and clean. Also remove the air filter and run it long enough to see if that's the problem. I have seen several in many years that looked real good but wouldn't let enough air through. Always start with the simple stuff first before you get into the more major things. I wouldn't get too carried away with too many additives at a time. A little may be good, more is not always better.

Change the fuel filters first. Then buy a cheap IR thermometer at any parts store and take temperature readings at each exhaust section. The exhaust manifold protrudes at each cylinder when you looking at from the side, its about level with the oil pressure fault sender. Take your readings for each cylinder and they should be very close to each other (usually around 180-190f). If there is a big difference in any of the cylinder readings, that cylinder would be causing the problem. Does the smoke smell like raw fuel or burn your eyes when your close to it? Usually blue smoke is caused by to much fuel but could also be oil burning off.

Everything you have been told so far are great places to start. I would change all the filters first. Have you drained the tank, cleaned, and put in known good & fresh fuel? Do that too, and put in a whole can of Seafoam. I would personally then let the system run at 50% load for as long as you have fuel (that is a level which is maintaining great burn temps, and you know it will hold the hertz there). Let the Seafoam do its thing through this entire first tank. You should change the fuel filters again after that. Be surprised what cleaning the fuel system, under load, can do for these things.

Blue smoke is oil, black smoke is fuel. Are you useing the load meter gauge to get your percentage readings? There prety inaccurate. Get a amp clamp meter.

I to would change the fuel filters and possibly drain the fuel tank. The generator is not going to run at max capacity if it cant get enough fuel and air.

After doing all the filters and fluids i would run it at the highest output it will run at for a few hours. Let everything get good and hot. Might also clean the wet stacking out if thats the issue.

as suggested in an earlier thread. i would change the oil to ATF and run for 40 min and then change the filter and put the regular oil back in.

Everyone has made good suggestions here. They just need to be put into the proper order. The only thing i will add, is while blue smoke tends to mean oil being burned in the cylinder, (Bmxenbrett) it isn't always the case.

Like everyone told you, do the filters. In any case, it can only help, not hurt.

As justacitizen stated, the ATF trick is a good idea, after the fuel filters. Why? because the engine is low hour. So normally, the rings should not be worn. BUT, what if a ring, (or rings) were rusted/corroded into place? Then you get oil in the cylinder.

Like jamawieb suggested, shooting a temp reading would help show if a problem was in a, (or several) cylinders.

If this were a high hour set, I would tell you to simply do a compression test on the cylinders. And that's always a good option.

Like most everyone told you, do the simple stuff first. One step at a time. Eliminate the simple stuff, so you do not have to pump out bucks to someone else, like your farm mechanic buddy. And you do not need anyone to do the compression test for you. Its too simple. Buy a gauge, (not all that expensive) and do it your self.

Thanks everyone for all the suggestions. I will try them in order starting with fuel filters, temp the cylinders etc.
the machine IS very low hour and super clean, could eat off all surfaces and no sign of soot or gunk anywhere before I started ... actually had not been drained before I bought it but I’m sure it sat for a long time so drained and refilled and replaced everything but fuel filters ... it’ll take me a bit of time to get back to it but I’ll let you know how it goes ... many thanks!

Jama, not to jump on someone else thread, but my 803 does burn my eyes when I get to close to exhaust. Is that a fuel issue? It does smoke when cold, than clears up in about 3-5 min.

jamawieb said:

Change the fuel filters first. Then buy a cheap IR thermometer at any parts store and take temperature readings at each exhaust section. The exhaust manifold protrudes at each cylinder when you looking at from the side, its about level with the oil pressure fault sender. Take your readings for each cylinder and they should be very close to each other (usually around 180-190f). If there is a big difference in any of the cylinder readings, that cylinder would be causing the problem. Does the smoke smell like raw fuel or burn your eyes when your close to it? Usually blue smoke is caused by to much fuel but could also be oil burning off.

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Are you getting blowby during operation? Should be a vacuum in the crank case during operation

There is a procedure in the engine -24 TM to explains how to test for the vacume and how to make a quick test, and how to make a water manometer.

CapePrep said:

Jama, not to jump on someone else thread, but my 803 does burn my eyes when I get to close to exhaust. Is that a fuel issue? It does smoke when cold, than clears up in about 3-5 min.

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Sounds like you have an injector leaking after shutdown. So when you start it, the cylinder is filled with diesel and it needs time to burn it off. Raw diesel burns blue, has a very noticeable smell and will burn the mess out of your eyes when you get up close or in an enclosed area.
To verify pull the injectors after it sits over night and the problem injector will be soaked, the rest will just have the usual carbon on them. This is somewhat common for me and after replacing the injector, you may have to run it for a while to burn off all the diesel residue in the cylinder.

OK it took me a long time to get back to this ... along the way we drained and cleaned the fuel tank, changed all the fuel filters etc., ran diesel purge thru the system, still running rough to me so i punted to my mechanic ... he pulled the injectors and had them tested, they checked out ok so he opened her up ... one cylinder ROCKER ARM BROKEN, PUSH ROD BENT, INTAKE VALVE BUGGERED ... as a reminder it is an 803A with 6 hrs showing, super clean looking after. Tier 2 reset ... I'm on the road so I can’t access the manuals I have but would love to hear some feedback before I get home? Rotten luck I guess... Right now he and I can’t lay hands on an engine model number the local cummins/onan dealer recognizes so we can price parts locally ... if we can get parts and head gasket set ill have him fix it ... but your comments and input would be welcome? Thanks

That sucks. You are going to want to look for Onan DN4M, or Lister Petter LPW4. Same exact engine (Onan is a rebadged LP in this case).

BA in CO said:

OK it took me a long time to get back to this ... along the way we drained and cleaned the fuel tank, changed all the fuel filters etc., ran diesel purge thru the system, still running rough to me so i punted to my mechanic ... he pulled the injectors and had them tested, they checked out ok so he opened her up ... one cylinder ROCKER ARM BROKEN, PUSH ROD BENT, INTAKE VALVE BUGGERED ... as a reminder it is an 803A with 6 hrs showing, super clean looking after. Tier 2 reset ... I'm on the road so I can’t access the manuals I have but would love to hear some feedback before I get home? Rotten luck I guess... Right now he and I can’t lay hands on an engine model number the local cummins/onan dealer recognizes so we can price parts locally ... if we can get parts and head gasket set ill have him fix it ... but your comments and input would be welcome? Thanks

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Howdy,

4 cylinder Onan DN4M, Lister-Petter LPW4, uses the same parts also 2 cylinder Onan DN2M, Lister-Petter LPW2

I would try alternate sources due to prices from a Cummins dealer. Yes, the parts can be gotten for a hefty $$ from them.

Good for you on having it properly checked. Those engine parts are not going to cost more than a few hundred bucks and could have saved you buying a new engine..and at that point its prob worth just finding a new set and haveing a parts set.

Is it just me or do these low hour nightmares seem to come along fairly often?

I still think a unit with a couple thousand hours seems to be a safer bet.

New machines can be problematic if the people operating them don't understand the proper way to run one in. Another issue is the hour meters on these machines are generally meaningless.

All 5 of the generators i have gone through were any where from 2hr to 390hrs. The 2hr one looked and ran like new. The higher hr ones showed age.