Mep 831A load issues

[grywitt]

Okay so the top ring was stuck in place. There are some scratches in the piston above where it (the gap) was stuck. I ordered a bore measuring tool. I thought for a minute that the timing was off because my dots didn't come together but with a little more turning they matched up. Ha ha.

Is a top ring stuck in place enough to cause the issue I've been having? I would like it if I could hone the cylinder and put it back together. I'll check the bad spots as well as diameter when I get the bore gauge. It wasn't that hard to free up the ring but it was definitely stuck at the end and only one end. The other end next to the stuck spot was free.

Like i said before I'm outside my expertise so advice is welcome and wanted. The rings actually seem to be in good shape to but I guess the smart thing to do is put new ones? I already tried to put a feeler gauge between the ring and the piston and it wouldn't go. It was .006 so bigger than the TM called minimum.

That same discoloration I saw on my rocker arms is on the crankshaft next to the rod rod bearing. Probably surface as well buy maybe that's where the explosion was leaking through. It is below where the piston was stuck. The oil was pitch black again. (No surprise)

This really is an awesome and fairly simple little engine i can see why it's liked so much. I'm excited to have this one running right. I'll probably never get rid of it.

 

[2Pbfeet]

Okay so the top ring was stuck in place. There are some scratches in the piston above where it (the gap) was stuck. I ordered a bore measuring tool. I thought for a minute that the timing was off because my dots didn't come together but with a little more turning they matched up. Ha ha.

Is a top ring stuck in place enough to cause the issue I've been having? I would like it if I could hone the cylinder and put it back together. I'll check the bad spots as well as diameter when I get the bore gauge. It wasn't that hard to free up the ring but it was definitely stuck at the end and only one end. The other end next to the stuck spot was free.

Like i said before I'm outside my expertise so advice is welcome and wanted. The rings actually seem to be in good shape to but I guess the smart thing to do is put new ones? I already tried to put a feeler gauge between the ring and the piston and it wouldn't go. It was .006 so bigger than the TM called minimum.

That same discoloration I saw on my rocker arms is on the crankshaft next to the rod rod bearing. Probably surface as well buy maybe that's where the explosion was leaking through. It is below where the piston was stuck. The oil was pitch black again. (No surprise)

This really is an awesome and fairly simple little engine i can see why it's liked so much. I'm excited to have this one running right. I'll probably never get rid of it.

Ok, not a ring expert here, so I will pass on whether one being stuck is enough.

However, I was taught always to have the gaps in the compression rings 180 degrees apart. Having both gaps aligned might be more than enough (I think) to explain your issue. The oil scraper ring should be +/- 90 from the lower compression/oil mist ring. I'm not finding Yanmar rebuild instructions for the rings, so please don't take that as per the manual.

Given the loss of cross hatching in the blackened area, I would not have any of the ring gaps in your blackened area if the ID passes muster.

All the best, 2PbFeet

 

[grywitt]

Correct me if I'm wrong. The carbon and smoke are from over fueling. So rings not holding proper compression mean each explosion isn't giving the expected power so it's sending more fuel to compensate. Hence over fueling?

I can at least see logic in that. I did find a guy around here that can to the honing and or boring for me. I'm in a terrible area for getting some things done. So either way I know where I'm getting the cylinder walls done. Now I just need to see if I need new rings or oversized piston and rings. Larger piston means more power right? Heck Ill be putting out 3.1kw.

I don't know engines enough to be sure I've found the issue but missing cross hatch and one end of a ring stuck sure seem possible. It was running pretty good and just not giving enough power.

 

[2Pbfeet]

Correct me if I'm wrong. The carbon and smoke are from over fueling. So rings not holding proper compression mean each explosion isn't giving the expected power so it's sending more fuel to compensate. Hence over fueling?

I can at least see logic in that. I did find a guy around here that can to the honing and or boring for me. I'm in a terrible area for getting some things done. So either way I know where I'm getting the cylinder walls done. Now I just need to see if I need new rings or oversized piston and rings. Larger piston means more power right? Heck Ill be putting out 3.1kw.

I don't know engines enough to be sure I've found the issue but missing cross hatch and one end of a ring stuck sure seem possible. It was running pretty good and just not giving enough power.

Yes, I think that bad ring alignment would lower compression, causing lower HP, causing the governor to call for more fuel, overfueling, smoke in the exhaust and excess soot in the oil. I have the hope that the black section isn't actually worn, it just has carbon deposits on it that could be honed off. As an explanation, I like that it might be this one item from the factory that caused the engine never to run well, and explains all of the observed issues.

0.5mm oversize isn't going to get you much extra HP, and as this is a generator with an electrically limited inverter output, I rather doubt that you would see any change from normal, though I hope the genset will run as designed. (And therefore better than it has been.)

Good luck- you've done a lot of work on this set; I think it owes you a debt for all of the TLC.

All the best, 2PbFeet

 

[grywitt]

Do i got my bore gauge. It's a cheap one but for my level of expertise it should be fine. I zero ed. I don't know how to write zeroed, zerod? It to the smallest dimension I could find in the cylinder wall. It has a .01 mm per mark measuring ability and I couldn't find anywhere in the cylinder where I even had a full mark difference. In the spot where the crosshatching is warn away I had about a half mark difference.

I did try setting my caliper to 78.02mm which is the middle of the scale in the book for the cylinder. I was within 2 marks on that measurement also but I think by then the way I set my measurements up there were to many spots for mistakes but I think the cylinder is fine and won't need oversizing. When I go to the machine shop we will verify but I'm ordering rings and rod bearings.

I considered reusing the rings but I broke one trying to take it out to see about cleaning the ring grove. That made up my mind for me. Then I asked Google if I should change a rod bearing even if it's not warn. Google said change it. I think the 45 hours on thy hour meter are correct so I'm hesitant to spend a bunch more money on already lightly used parts.

 

[2Pbfeet]

Using a dial gauge can be a bit fiddly until you get the hang of it, but if your cylinder is within .005mm (0.0002") that's great. The new rings aren't going to hurt. I didn't see anything in the bearings of concern to me, but it is your generator.

Just offset the three rings correctly, and I would do it so none of the three rings have a gap in the blackened area.

All the best,

2PbFeet

P.S. A training video on bore indicators/dial gauges if interested.

 

[grywitt]

I got the block back today. I had it bored out .5mm and started reassembly. I'm excited to see this thing run right. I pulled the valves and cleaned them up. I put the crank shaft, balancer shaft and cam shaft installed slid the piston into place. I put the flywheel on.

I ordered Yanmar push rods so I'm waiting to put those in. I still need to get the actuator slipping on it's shaft figured out. I'm thinking of drilling through it and putting a pin in it. I'm still hoping i can remember how it all goes back together.

 

[2Pbfeet]

@grywitt If it were me, I would lean towards a glue (thread locker /locktite), rather than a screw, so if it ever were to need adjustment, it would be posssible. If the surface is worn or pitted from the slipping Locktite makes a metal laden locker that might help (Locktite 660). The 660 on the actuator might benefit from some accelerant, if you go that route.

All the best,

2PbFeet

 

[grywitt]

You always seem to have good ideas. I've tried straightening the clamp a little and cleaning the shaft plus the original bolt was bent also so I put a new one but it still is slipping. I'll check out that lock tight idea. I honestly didn't know they had a product for that.

 

[2Pbfeet]

You always seem to have good ideas. I've tried straightening the clamp a little and cleaning the shaft plus the original bolt was bent also so I put a new one but it still is slipping. I'll check out that lock tight idea. I honestly didn't know they had a product for that.

Henkel, makers of Locktite, have adhesives for all sorts of things that get esoteric pretty quickly. Fun to browse if you like that sort of thing. So do 3M and Corning/Dow.

I didn't know about the 660 either until I had a key fail in a keyway that then wallowed out the keyway on a shaft that would have been a huge hassle to remove from service, get the old shaft pressed out and make a replacement, as there aren't replacement shafts available. Nothing like being between a rock and a hard place to give one incentive to innovate.

All the best,

2PbFeet

 

[grywitt]

What fun. Okay so I got it reassembled the engine and pmg any way. Enough to test it. It didn't want to start then coughed up white then black then white smoke then smoothed out. It wouldn't engaged the output contactor and there was no power from the gfi. I had power at the inverter though. Ha ha the gfi needed reset...

I ran it for a bit without the actuator. I shut it down then fired it back up and the output contactor would close. I reinstalled the actuator fired it up and got it adjusted to about 5/16. And went and got my load bank. ( I will need to play around a bit with the magnet since once I connected the load bank it died. I pretty sure the magnet grabbed it while it was adjusting throttle for the partial load. At that point the only load was the fan.

While running up the load it wasn't doing great and I think that's actuator issues. I locked in full throttle and got up to 3kw. It was pretty smoky but held. I pulled the air filter and 3k was smooth then I tried 3250 for a bit. It held but was smoking like 2500 used to. I will get a new air filter and get some of that. 660 stuff. I'll get the outer housing put back together then run it for a day at load to make sure. I think it's fixed for the most part. Heck if I didn't want to throttle down it would be great already.

It was nice watching that machine hold 3250 like it was nothing. I think i will give it another oil change to get any rebuild and honing garbage out of it too.

 

[grywitt]

I forgot the pics.

 

[2Pbfeet]

Looks nice!

 

[grywitt]

I'll get those wires cleaned up and tidy it up more but I'm pretty happy with it. I've been fixing things most of my life but that's the farthest I've torn down an engine (especially diesel) by my self. I was a little intimidated but excited too. These really are awesome little machines. I've been frustrated a little but having fun the whole time. Thank you for the suggestions and pointers along the way. I'll get it buttoned up and give it a good load test soon. I think it's going to do good.