803A Hits a Wall at 9.3kW

[LuckeyD]

Good Day. Your initial issue is your gen shuts down after a while on a load that is gradually increased with messing with it. The key was when the oil pressure gage goes under 20PSI. The LOP switch shuts you down as it is set at about 20PSI or just below. Fresh oil allows it to go a while then you shut down again; am I correct? Again oil pressure was below 20PSI on your gage. Please put an oil gage on the thing and i recommend using the same oil line as that LOP. Now you read on a gage what you have confirming the gens already in place gage system. Please note your pressure especially on shut down. Should start out about 40 +and decline to 20 or less upon shut down. If this is the case, you have work to perform. Here is a test, with gage attached, disconnect the LOP wiring. Observe pressure as gen warms up and it will go longer but shut it down below 15-18 PSI.) What's happening is as oil passage ways and oil pump bypass pressure setting warm up the bypass setting is allowing too much oil to bypass. Add this to main bearing wear, your oil pressure will not allow the engine to keep running and the LOP shuts you down. Using 50 weight oil will only prolong things a tiny bit. You can test piston rings for compression, they will probably be in tolerance or hair line in tolerance. Using plastigage you can read the main bearing wear. I had one Warrant Officer try adjusting the oil pump bypass and had oil leaks everywhere as it was adjusted too high. Touchy setting. There should be a Lister-Petter engine manual in the forum for tolerances and settings as you rebuild your engine. Onan has parts, but may take a while to obtain bearings, rings and oil pump(the bypass setting is touchy). I do hope I am all wet, but I have seen this action countless times in war zones. Let us know what you find.......

 

[handyjay03]

Initial discovery was that I couldn't get it above 35.5A. Figured the oil pressure gauge was acting up since I have a bad fuel gauge and malfunctioning ammeter. I can make it to 39.6A now if I get it just right. Oil pressure has seemed low to me since I brought it home. The only time I've gotten low oil pressure trip light is when I couldn't catch it from shutting itself down from a load. It'll run all day with the gauge reading 18psi though.

 

[LuckeyD]

An extra gage you can verify your panel gage. The panel gage may be incorrect. The LOP is set for just under 20PSI. Hope so ruling out engine work and there is another issue. The gen should deliver 50 AMPS per phase set on 120-240. The LOP light will always come on if the gen shuts down for an unknown reason on its own. Now comes the questions: As you load your gen does it start to slow in RPM, generate black smoke, and about what current level? You say 39 AMPS. Only concerned with what an AMP probe would measure to your load at this time. Do you measure 120VAC between terminals 3 and 4 on the voltage regulator as you raise the load? Next, this is strange- Do you hear a whining sound from the main gen? Hard to hear main gen whine because of the engine but you hear that main gen whine. Had several TB3 and S8 and K1s with miswiring issues and the main gen fought its self. Does the K1 or S8 heat up someplace? (check just after shut down and i mean hot) Next test if able: all shut down, change the s8 to 120VAC. Output only 120VAC read only at L3 to L0 (L0 is also chassis ) Now start and see if you are able to achieve a higher load using only 120 single phase. 104AMPS is 100%. Does your gen start slowing again around 60-75 AMPS. The answers rule out components or point to components and I'm not trying to get you upset. You could have a fuel issue and the engine is starving or it has low compression, or an electrical issue if oil pressure is 25-35 PSI nominal and answers dependent.

 

[Ray70]

I was finally able to look at it again this afternoon. Set my frequency to 60HZ with the 4590W load on it, and it stays around 61.5Hz with no load. It will now hold about 9300W at 58.5Hz, but cannot hold engine speed above that. I have about 3hrs of loaded runtime on it since picking it up. It still blows black smoke steady from 8520W and above, but it is not heavy.

Shot temps where the red circles are, which seems to be the valve covers, inboard the exhaust manifold. Typically getting 350 on the cylinder closest to the radiator, and 425-430 on the subsequent three. Also looked at the placement of the metering pumps, and the one for the outlying cylinder has some room to rotate counterclockwise a little bit. I have attached pics of both.

Regarding the exhaust temps, you want to be taking the temp from the head BELOW the exhaust ports. The area you show with the red circles is in fact the valve cover and will not give accurate exhaust temps. Hit that flat green area right below the exhaust manifold instead.
Block airflow from the fan, start the engine let run a couple minutes and measure temps.

 

[LuckeyD]

OK, you got 9000 watts. Run it with that or about 8500 Watts and after a while it may even provide more as the rings seat again and wear into place. For now use 9000 as your 100%. When you get time do a compression test. Compare with manual., and each other. At the moment, it sounds like rings are worn. Compare with the Lister-petter manual in the forum. Black smoke is the fuel system at 100% fuel being injected into the cylinders. Some may show as unburnt and collect in the muffler. Lighten the load to just where the smoke starts and use that as the wear in load. This comes from pitted cylinder walls and the rings after a while no longer seat properly, like under a light load being used too long creating a varnish coating on the cylinder walls that gets burnt off as yours is doing.

 

[handyjay03]

Regarding the exhaust temps, you want to be taking the temp from the head BELOW the exhaust ports. The area you show with the red circles is in fact the valve cover and will not give accurate exhaust temps. Hit that flat green area right below the exhaust manifold instead.
Block airflow from the fan, start the engine let run a couple minutes and measure temps.

That was where I shot initially because it made sense. Temps were between 199 and 201, which coincided with what my temp gauge was reading. Did not have cardboard blocking the fan though, just the side door open. Temps have always been at what looks like 190-200 on the gauge when it gets warmed up.

So far, I've got about 5-6hrs of running it between 50% load and as much as it can hold, with the vast majority at it's max.

 

[handyjay03]

An extra gage you can verify your panel gage. The panel gage may be incorrect. The LOP is set for just under 20PSI. Hope so ruling out engine work and there is another issue. The gen should deliver 50 AMPS per phase set on 120-240. The LOP light will always come on if the gen shuts down for an unknown reason on its own. Now comes the questions: As you load your gen does it start to slow in RPM, generate black smoke, and about what current level? You say 39 AMPS. Only concerned with what an AMP probe would measure to your load at this time. Do you measure 120VAC between terminals 3 and 4 on the voltage regulator as you raise the load? Next, this is strange- Do you hear a whining sound from the main gen? Hard to hear main gen whine because of the engine but you hear that main gen whine. Had several TB3 and S8 and K1s with miswiring issues and the main gen fought its self. Does the K1 or S8 heat up someplace? (check just after shut down and i mean hot) Next test if able: all shut down, change the s8 to 120VAC. Output only 120VAC read only at L3 to L0 (L0 is also chassis ) Now start and see if you are able to achieve a higher load using only 120 single phase. 104AMPS is 100%. Does your gen start slowing again around 60-75 AMPS. The answers rule out components or point to components and I'm not trying to get you upset. You could have a fuel issue and the engine is starving or it has low compression, or an electrical issue if oil pressure is 25-35 PSI nominal and answers dependent.

I'll try and answer some of your questions. Yes, frequency does drop with load, and smoke does also increase from none at a light load to a consistent, visible black smoke at heavier loads. It is not heavy smoke at all. It's able to hold 120V and 240V perfectly no matter the load. No whining sound, just the engine chugging along. No increased temps on K1 or S8. I have no way to pull that amount of load on 120V, just 240.

 

[spotrep]

Its mentioned above but this is a must have mod in my opinion.

To make it as easy as possible for you:
you will need a brass tee: https://www.amazon.com/gp/product/B0B9M4HKMT/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8

and a gauge: https://www.amazon.com/Marshall-Instruments-CW00060-Pressure-Gauge/dp/B00TYY3SRA/ref=sr_1_13?sr=8-13

 

[handyjay03]

Ordered that stuff last night and gauge will be here Thursday. Got a new fuel gauge in yesterday. If it isn't raining later, I'll go install that and try and run through the TM troubleshooting for the oil pressure gauge and sender.


Update: New fuel gauge is working. Couldn't get the oil pressure gauge to react to any resistance changes I made with the voltage pot as per the TM. Seemingly followed it to a T, and tried the full procedure twice. Didn't have time to check the sender.

Two things I was unsure of. I was taking the resistance measurements at the 156A and 157B wires because I couldn't get the wires unhooked from the voltage pot. The TM didn't specify if that was okay. Also, was I supposed to remove the sender and ground wires from the gauge before jumping from 156A and 157B? I figured that would mess with testing, so I took them off