Mep 831A load issues

[2Pbfeet]

I'm glad you got the muffler cleaner!

Congratulations on having scored a brand new second engine. As it is new, (ish?) I wouldn't load it up too much in the first 5-10 hours, though I would vary the load, I would take it to full load, just not for very long, and I'd change the oil between 10-20 hours if it were a new Yanmar, but I don't know about the military stored and preserved engines.

I do find it a bit troubling that the rebored and honed engine is already wallowing out and wearing that part of the cylinder wall. That seems way too fast. Was anything besides the piston and rings changed? Connecting rod? Pin? Was the crankshaft checked for alignment and / or damage? It does make me wonder about which came first, the chicken or the egg...did the rings break because something was out of alignment from the factory (and still is), or did the rings breaking cause the other issues? Or...?

You have quite the saga here.

All the best, 2PbFeet

 

[grywitt]

I was pretty disturbed by that myself. I think that's less than an hour of running and it already looked like that. When I saw that I thought for sure the rings were going to be wrong. But no. I will have to say no to all of those questions you had. The rod piston pin ect are all the same pieces. The crank shaft seemed okay. Definitely wasn't checked for alignment though. I wouldn't know how to do that. Figuring out the answer to why that's happening is outside my knowledge and skillset. I was wondering if maybe the oil pump system isn't working right? I had oil at the rockers ect though.

This has been interesting for sure. Every smoking gun i find and I think ha ha. This will be it for sure. Then nope. The engine turns easily by hand and doesn't feel like anything is binding or dragging. I'm pretty lost. It will be interesting to see how this other engine works. I will follow your suggestions for break in. A small amount of oil came out when I pulled the plug to install the drain valve and temp sensor. I'm not sure what kind of oil it was. After putting the oil in it I held the compression release and pulled the start cord a bunch of times to try to get some oil circulating. Hopefully it primed the injector too.

I'll update this thread that doesn't end as things progress.

 

[2Pbfeet]

As you point out, you had oil in the rockers, and no signs of wear there, or elsewhere, other than that patch on the cylinder wall. When the oil pump/system isn't working, the engine doesn't get very far. I don't think that the one sided wear is an oil issue, it looks to me like an off axis alignment issue, which I've never seen in person. Usually if something bends anything in the pin/rod/crank axis, something rather catastrophic results. Based on the fact it is a patch part way down, I'd wonder if the crankshaft was off, but I really don't have a clue.

Keep us posted.

All the best, 2PbFeet

 

[grywitt]

Okay update.
As of right now the new to me engine has been running for 3.5 hours at various loads. I've been changing the load about every 15 minutes.
I started at 500 watts for a few minutes then 1kw for a few minutes then gave it 1.5kw for 15 minutes. Then 2kw for 15 ect. About the 2kw point I tried 3kw for a short time while I was there to see what it would do. Run 3kw is what it would do. A little smoke but not much. I did try 3250 just to see for like 30 seconds and it held but smoked pretty good. I've been fluctuating between 2, 2.5 and 2.75 loads.
I did let it warm up for about 10 minutes before any loads. It does smoke a little at 3kw but not much but I'm trying for no smoke. I think this would be the 3000' elevation showing up.

So now I'm really curious what's up with the other engine. It has never ran like this. I wonder if there is someone that makes YouTube videos that wants to disect this problem. I really want to know. Heck I might have it fixed and not know it but I don't think so. Maybe one day if I get bored I'll put it back in the gen and see what happens.

I'm going to run this gen all day changing loads maybe hourly now. It's at 2750 right now and purring. I think I'm seeing how this 831 is supposed to run.

 

[grywitt]

Some interesting things I'm finding reading the manual. First I didn't check the parralelity of the rod. Maybe I should check that. Also the description of the rod and which engine it goes in don't match what I have it says the L70 gets a through bolt and I have the push bolt. Maybe it's nothing but I think it's time to explore all possibilities now. Oh and has anyone heard of selectivery?

Update on the machine. It's been running 5 hours now and the last hour has been 2750 with basically no smoke. I'm going to go run it at 2250 for an hour.

 

[grywitt]

Hello

Get a dry, clean, empty milk gallon jug.

Pull the supply line off the injector feed side of the filter. Attach a tube long enough to get into your jug. Flip the switch to prime, and that jug should be pretty close to half-full within 60 seconds and have a decent spray with each pump stroke.

If the spray is weak, or feeding very slowly, start looking at the filter, strainer (little metal can attached to the filter), and finally the pump itself. If you get to the pump itself, the main pump and aux pump are interchangeable-- switcharoo.

Another thing to try is pull the return line post injection pump and injector. Put that into your jug (with everything else connected properly) and start / run the engine. You should still be getting damn near 1/2 gallon a minute returned on idle.
[/QUO

Hello. Quick question. I see the spot for adjusting the frequency. Do you just dig out that back plug? Then is it just a small termination screwdriver? The frequency is at 59.3 but I might as well make it perfect if I can.
Thank you Gary

 

[2Pbfeet]

Some interesting things I'm finding reading the manual. First I didn't check the parralelity of the rod. Maybe I should check that. Also the description of the rod and which engine it goes in don't match what I have it says the L70 gets a through bolt and I have the push bolt. Maybe it's nothing but I think it's time to explore all possibilities now. Oh and has anyone heard of selectivery?

Update on the machine. It's been running 5 hours now and the last hour has been 2750 with basically no smoke. I'm going to go run it at 2250 for an hour.

My guess is that is a japanese to english translation issue. Selectivery=selectively. My recollection of the manual is that it has a few gems.

Can you find a part number on the conn rod? (FWIW: I have never seen a through bolt version.)

I'm glad to hear that the replacement engine is behaving as one would expect!

All the best, 2PbFeet

 

[grywitt]

My guess is that is a japanese to english translation issue. Selectivery=selectively. My recollection of the manual is that it has a few gems.

Can you find a part number on the conn rod? (FWIW: I have never seen a through bolt version.)

I'm glad to hear that the replacement engine is behaving as one would expect!

All the best, 2PbFeet

I'm glad to see it working correctly also but it honestly doesn't feel like a win. Heck I threw an entire new engine at it. I did reassemble the engine and put oil in it because I don't like the idea of the engine sitting there dry. I think i will end up draining the oil and disassembling it again though. I want to check everything. I didn't see a direction the rod went for sure. It looks like it's the same both ways and I didn't see marks to know. I did put it back in the way it came out but maybe it was wrong. I don't know. I'm hoping to build a shop soon and I'll be able to be more organized and clean.

 

[grywitt]

When

I'm glad to see it working correctly also but it honestly doesn't feel like a win. Heck I threw an entire new engine at it. I did reassemble the engine and put oil in it because I don't like the idea of the engine sitting there dry. I think i will end up draining the oil and disassembling it again though. I want to check everything. I didn't see a direction the rod went for sure. It looks like it's the same both ways and I didn't see marks to know. I did put it back in the way it came out but maybe it was wrong. I don't know. I'm hoping to build a shop soon and I'll be able to be more organized and clean.

When I look at my pictures when I took it apart and the way the book says to install it i think the rod might be backwards. To look at it it doesn't look like it would matter but it does say to turn it a certain way. It looks to me like it says the flat spot with the 106 should be towards the fuel pump side and it wasn't

 

[grywitt]

Okay. I think this thread can end.
I don't have 831 load issues any more. I just ran it for over 6 hours at lots of loads and the last half hour was at 3kw. At the end of that half hour the gens was just slightly puffing a tiny bit of smoke but not an issue and it held fine.

Unfortunately the fix was a whole new engine but I do still have the original and it was low hour and still a mystery to solve. Maybe when I explore that problem Ill start a new thread.

Funny I've seen the 831s sell for what I thought was some ridiculous amounts but the only difference is they spent it all at once and I spred it out. Ha ha ha. I do still have a lot of parts though.

Thank you to everyone who helped me try to get this fixed.