Mep 831A load issues

[2Pbfeet]

Also both injectors looked the same when they came out. Pretty coated in carbon. It's that pretty normal?

Not in my experience. It seems as if your engine is being overfueled.

If it were me, I would go back to try fueling the high pressure pump directly again and see if that improves your load and smoke. If it doesn't, I am starting to wonder if pulling the engine to check the camshaft timing and the rings might be in order. Sorry.

All the best, 2PbFeet

 

[grywitt]

Not in my experience. It seems as if your engine is being overfueled.

If it were me, I would go back to try fueling the high pressure pump directly again and see if that improves your load and smoke. If it doesn't, I am starting to wonder if pulling the engine to check the camshaft timing and the rings might be in order. Sorry.

All the best, 2PbFeet

It will be a good learning experience. The more I dig into this thing and study the more I learn. It does seem like 1 degree of adjustment isn't leaving much room. This is the one shim under the fuel pump. Soon I'll get set up and start digging in. I'll post pics and I'm sure have some questions along the way.

 

[vrzff]

Question. What happens if you run it with no air filter?

Next question. Do you have an air compressor? Next time you load test and it starts to stumble, start blasting some air into the filter housing (with filter in). Don't go nuts, just a steady low-force blow. Does it catch back up and stop stumbling?

 

[grywitt]

No air filter is the same. I'll try the air trick but I've pretty thoroughly checked the restricted air possibility but ill try anything since i obviously don't have the answer.

 

[grywitt]

Quick question? Does any body have a recommendation or warning about gasket kits for these? I see many options on ebay. I just don't want to make the mistake of using junk or are they all the same? I suppose I should change any gasket i open right? I thought I should put new sleeves on the valves too while I'm in there. I guess I will need a spring compressor? I've never taken valves out before. Any advise is welcome and appreciated.

 

[vrzff]

Quick question? Does any body have a recommendation or warning about gasket kits for these? I see many options on ebay. I just don't want to make the mistake of using junk or are they all the same? I suppose I should change any gasket i open right? I thought I should put new sleeves on the valves too while I'm in there. I guess I will need a spring compressor? I've never taken valves out before. Any advise is welcome and appreciated.

I generally only change head gaskets, and reuse others that are not torn. I've had very good luck with the Ebay ones.

 

[LuckeyD]

The 831 runs at 2 speeds. No load(or lite loads) and heavy load speeds. Attached is how you adjust the Governor.

The magnet setting to hold the governor lever in the stop position is Factory set. If you mess with it all you have to do is adjust it back unscrewing it till it holds the plate again. At low or full loads the plate is about 5/16 to 7/16 of an inch away from the shut down held by the magnet position. The plum wire was used to set the high end of the engine for full load highest setting 3800 RPM. Just use a DMM to measure ACV at Pins A to C of the Governor control in the control box. 178VAC at no loan and 194 at full load, and it shuts off when you shut the gen down, and you are in business.

 

[grywitt]

The 831 runs at 2 speeds. No load(or lite loads) and heavy load speeds. Attached is how you adjust the Governor.

The magnet setting to hold the governor lever in the stop position is Factory set. If you mess with it all you have to do is adjust it back unscrewing it till it holds the plate again. At low or full loads the plate is about 5/16 to 7/16 of an inch away from the shut down held by the magnet position. The plum wire was used to set the high end of the engine for full load highest setting 3800 RPM. Just use a DMM to measure ACV at Pins A to C of the Governor control in the control box. 178VAC at no loan and 194 at full load, and it shuts off when you shut the gen down, and you are in business.

Copy that. Thank you. I feel like I have done this. The wire and lead were in tact when I got the unit so I'm thinking those are at least where the factory put them. The lead has since fallen off but the wire is still in the hole. I did adjust the full load voltage with the actuator held in the the manual start position. I'm having trouble with the actuator arm slipping on its pin but I will get that straightened out if I have to drill a hole and pin it.

 

[grywitt]

I made this video of checking the injection timing. Can anyone tell me if it looks right or I'm doing something wrong. This video is with no shims under the injection pump because I haven't put it back in since I decided to see what would happen if I took it out. I watched a u tube video of a guy that said if you are at 3 to 4000 feet try taking out a shim. The one shim it had/ has is the smallest one. You start seeing some fuel at about 4 or right in that area. But the larger amount of fuel is between 3 and 2 marks.

 

[grywitt]

I've made a few videos of different tries angles ect. I put the one shim back in and if anything i think it shows more that I need more. Probably it was the fact that I hooked up batteries and had the fuel pump running though.

I'm wondering if someone pulled the pump and only reinstalled it with one shim. I feel like I might need 5 degrees of shims ish. Please if you are taking time to look maybe check my other videos also. That way I don't need to post links to them all.

Thanks again

 

[grywitt]

I'm going to set it up with the fuel injector hooked up but not in the cylinder then try to see exactly when it pops. Seems like the only way to know for sure. I'm not fully understanding the TM on how I check the timing. I thought that's what I was doing.

 

[grywitt]

So as i add shims and get closer to TDC I think I realize the TM is backwards? The TM says if it's before 16 add shims. What am I seeing wrong? I did check the injector spray and timing and it looks good and happens at about 5 degrees.
Since add far as i can tell now I need to remove shims I don't have to remove that either something is missing from my injection pump.
( a spacer or something) or my actual timing marks are off?

 

[2Pbfeet]

In my experience these engines very rarely need timing adjustment. I have never done it.

The procedure is in the Yanmar service manual.
https://discount-equipment.com/library_files/21623.pdf

Bear in mind that injection starts about 13 degrees BTDC in this engine;


All the best, 2PbFeet

 

[grywitt]

In my experience these engines very rarely need timing adjustment. I have never done it.

The procedure is in the Yanmar service manual.
https://discount-equipment.com/library_files/21623.pdf

Bear in mind that injection starts about 13 degrees BTDC in this engine;
View attachment 954146

All the best, 2PbFeet

Copy that. I just thought maybe someone took it apart and didn't put them all back. The TM says 16-18. .. 13 is what I was seeing. Then the TM says add shims to add degrees but that's backwards right? Closer the the lobe adds degrees yes? More shims means less degrees?
I'm pretty confused about what might be causing this. The injector spray looks good seems to be about on time from what I can tell. The injector seems to pop about 5 degrees. I've found no info about of that is correct but if you start pushing fuel at 13 should be about right.

I took the head off and it looks like this. Seems okay to me but I don't know. The valves seem to be seated pretty well. I sprayed oil on the top with them closed and none seeped through. The cylinder wall has a couple spots that are a little rough/ pitted. I try to get pics of that. You can see it a little in the one Pic. I'm struggling to get the pmg pulled so I can take the side cover off.
I'm happy to take any suggestions on where to go from here.

 

[grywitt]

The one head stud bolt is really rusty. Not sure what to think of that as well. The head gasket looked okay to me no obvious leakage. I sprayed pb blaster in the cylinder on the piston and it stayed for quite a while. As i moved the piston up and down there did seem to be a spot where it might have leaked. Ill need to play with that more to be sure.

 

[2Pbfeet]

I do not understand the rust. That area shouldn't get water. The fact it did makes me wonder if water ever got into the cylinder, and caused ring damage.

The timing looks ok to me, and that brings me to...

You have been chasing so many gremlins (and have fixed so many with not much change), that I think it may be time to check the piston rings, since you have timing that seems in the ballpark, reasonable injector pattern, ok valve clearances, no obvious head gasket or valve leakage, and what appears to be reasonable governor function.

All the best, 2PbFeet

 

[vrzff]

I'm in agreement with PB, worth a look at those rings since you're already this far.

Also going to add, are you sure that head gasket wasn't rusted out and leaking? That soot on the underside of the air intake makes it look like you were shooting combustion gas at it, right past the gasket. What did the actual gasket look like? The whole mating surface looks like crap.

Food for thought.

 

[grywitt]

I'm definitely going to do that once i figure out how to get the PMG out of my way. I do need to get the rotor out of the stator yes? Can I take the retaining ring off and pull them both together? I got it to come out about an inch so far but my puller isn't correct. Can someone recommend the right puller fit the job? I've been searching like crazy.

Here are some more pics of the cylinder and head gasket. I looked pretty close but didn't think I saw any evidence of leaking through the gasket.

I'll circle the spot on the cylinder wall that looks wrong to me. I don't know how bad it has to be to cause problems but I'm thinking you might be correct 2pbfeet.

 

[2Pbfeet]

I'm definitely going to do that once i figure out how to get the PMG out of my way. I do need to get the rotor out of the stator yes? Can I take the retaining ring off and pull them both together? I got it to come out about an inch so far but my puller isn't correct. Can someone recommend the right puller fit the job? I've been searching like crazy.

Here are some more pics of the cylinder and head gasket. I looked pretty close but didn't think I saw any evidence of leaking through the gasket.

I'll circle the spot on the cylinder wall that looks wrong to me. I don't know how bad it has to be to cause problems but I'm thinking you might be correct 2pbfeet.

If you didn't have an issue, I might give it a miss, but yes to my eye, that is a sign of an issue. Do you have access to a dial bore micrometer (internal micrometer)? I'd be curious how deep that patch is. If it turns out to be necessary, one can get oversize pistons and rings for this engine. I think that the NSN is 2815014771358, Yanmar 714880-22580, available at the moment.

Again, from an armchair in a galaxy far, far away, I have the concern that worn (no honing marks) and black patch is a sign of broken rings that are causing slightly reduced compression, that in turn causes incomplete combustion and smoke. Blow by at that location might also explain why your oil was/is so black with so few hours.

All of this plus the rust does make me wonder if this was a hydrolock event. The fact the soot marks don't extend too far into the cylinder suggests that the connecting rod might be ok, and the lack of metal fragments in your oil change is also reassuring, to me at least.

So, yes, I do now really think that the time has come to have a look at the piston rings.

All the best,

2PbFeet

 

[grywitt]

I found a thread on here about getting that pmg off and the tool to use. Stop looking i found it. I will be digging into this engine soon. I don't have an internal micrometer. I should probably start looking into which shops around here might bore that out for me. This is getting outside my knowledge. This is where I have an awareness level experience and not experience. I wish someone around here would show/ teach me.

I'll be back with more updates