Mep 831A load issues

[grywitt]

@grywitt Did you clean the engine off?

The cooling fins look brand new. (As in 24hrs new, so believe the hour meter.)

I think that getting really black oil out of an engine isn't super unusual- if it has a bunch of hours on it. The carbon never really comes out of the sumps in my experience. (So don't believe the hour meter)

That raises the question to me of how does one get a machine that runs at 1/2 its rated output (+/-) and has a bunch of carbon in the oil if this is a new engine? (Believe the hour meter)

The inconsistency that I see is that even though there is debris in various places in your unit, the fans and fins look really clean, as does the muffler insulation, wires, etc. To me, that argues for the hour meter is probably in the ball park. The oil argues for either much higher hours, or yes, something more serious like broken rings, or damaged valves or valve seats, or the valve guide seals are missing, or something like the decompression lever is always at least partially engaged, or there's half a rag behind the engine preheaters. I think that it is running too well for the camshaft not to be correctly aligned, but it might be possible. When you turn the engine over by hand, is it easy or hard to turn over? Without the decompression lever, this should be pretty darn stiff. If it is hard, I'd take the head off and look for foreign material.

No matter what, I'd button down the fuel lines first.

If you prime the set with the output of the Racor into a clear jar, can you see bubbles? Or do you have a segment of clear fuel line that could temporarily go between the last Tee fitting and the injection pump? It might be a quick test for bubbles. You may be looking for 1/16th inch sized bubbles, so I find a bright flashlight helps. If you find bubbles, I think that means hunting down the leak. If you have bubbles, if it were me, I would go from the tank to the injection pump and disassemble and clean the threads and barbs, checking for debris, and then use a good diesel thread sealant on the threads. Because this engine is so persnickety about air leaks, I prefer to use the style of hose clamps that don't have flat spots at the tightening mechanism. (I couldn't really see the defect that you were concerned about on the injector, but as you have clear hose, if it were me, I would lift the hose up and see if the bubbles accumulate, or move downstream.)

My bet at this point, if the compression is low, would be on broken rings, but I'd be open to something odd. Carbon issues in a twenty hour Yanmar is more than unusual, so something is amiss.

Sorry for the long post, but even if the engine were poorly fueled (overfueled), I have trouble spinning a scenario that lays all of the blame on an air leak and gets the oil to be that dirty, though the better performance on the segregated fuel return suggests that there is an air leak, even if it doesn't cause 100% of your issues. If it had just been SeaFoam, the subsequent test should have been better and they weren't.

I am open to any critiques. All new fuel lines more pics coming. I used pipe dope on all the tees. Used clamps that crimp. Doubled some clamps where the barb was long enough. I was very careful not to get pipe dope beyond the threads into the line.

 

[grywitt]

I am open to any critiques. All new fuel lines more pics coming. I used pipe dope on all the tees. Used clamps that crimp. Doubled some clamps where the barb was long enough. I was very careful not to get pipe dope beyond the threads into the line.

I also filled the filter with sea foam and ran the pump for a while. The when I bumped the start button it started before one revolution. ( it seemed anyway) with it starting that easy or would think the timing should be correct hu?
Any way i ran it for a minute or two now I'm letting it sit for a while before I test it again. That's today so far. Thanks for watching. Ha ha

Well nothing changed. That's a lie it does have all new fuel lines. The last two pictures I think might show the problem. Certainly not helping. I'm a little embarrassed that I had pulled it out once but apparently didn't hold it the right direction to see the bend. My bad. I guess now I know why I had to adjust the valves both times I checked them. This is the exhaust valve pushrod. Well I'm not a diesel mechanic but I'm learning. I ordered new push rods. Should I be looking for further damage besides this? Should I pull the head and clean the combustion chamber or just try to burn it out once I have new push rods?

I hope this is the problem. It could make sense of the issue.

 

[2Pbfeet]

I also filled the filter with sea foam and ran the pump for a while. The when I bumped the start button it started before one revolution. ( it seemed anyway) with it starting that easy or would think the timing should be correct hu?
Any way i ran it for a minute or two now I'm letting it sit for a while before I test it again. That's today so far. Thanks for watching. Ha ha

Well nothing changed. That's a lie it does have all new fuel lines. The last two pictures I think might show the problem. Certainly not helping. I'm a little embarrassed that I had pulled it out once but apparently didn't hold it the right direction to see the bend. My bad. I guess now I know why I had to adjust the valves both times I checked them. This is the exhaust valve pushrod. Well I'm not a diesel mechanic but I'm learning. I ordered new push rods. Should I be looking for further damage besides this? Should I pull the head and clean the combustion chamber or just try to burn it out once I have new push rods?

I hope this is the problem. It could make sense of the issue.

TAAADAAA! Congratulations.



I hope that this fixes it for you. Yes, new tappets and proper valve settings should do a lot for the engine performance.

Nice job on the hoses.

I am sorry that it so long to surface the bent tappet, but to me a bent tappet would explain the bad valve clearance you noted at the beginning, the fact that it changed on you, the inability to maintain load, the black oil, and the signs of the overfueling. Nice to have a consistent problem, though the separate fuel lines does argue for the set having had a small air leak as well. When you do get the new tappets in, and if the machine is running ok, I'd change the oil one more time on the bet that there is unburnt diesel as well as soot washed down into the oil.

FWIW: at least in my experience with these engines bending tappets often seems to happen when the valve clearance is either too tight, and can't handle the differential thermal expansion, or surprisingly, (to me at least), if the valve clearance is too large, as the tappet seems (I guess) to bounce around and get hammered by the closed rocker arm.

All the best,

2PbFeet

 

[grywitt]

TAAADAAA! Congratulations.



I hope that this fixes it for you. Yes, new tappets and proper valve settings should do a lot for the engine performance.

Nice job on the hoses.

I am sorry that it so long to surface the bent tappet, but to me a bent tappet would explain the bad valve clearance you noted at the beginning, the fact that it changed on you, the inability to maintain load, the black oil, and the signs of the overfueling. Nice to have a consistent problem, though the separate fuel lines does argue for the set having had a small air leak as well. When you do get the new tappets in, and if the machine is running ok, I'd change the oil one more time on the bet that there is unburnt diesel as well as soot washed down into the oil.

FWIW: at least in my experience with these engines bending tappets often seems to happen when the valve clearance is either too tight, and can't handle the differential thermal expansion, or surprisingly, (to me at least), if the valve clearance is too large, as the tappet seems (I guess) to bounce around and get hammered by the closed rocker arm.

All the best,

2PbFeet

Thank you again for the help. I'm hesitant to get to excited that's the problem but it sure does seem like the right disease for the symptom. I do like the new fuel lines. Would you take the head off and have a look or just put the new pushrod in and try it? The Yanmar book says not to go any further than you have to.

I'm not sorry it's taking so long. I'm way less intimidated by that motor than I was. I needed that. I'm learning tons. The times I've learned the most as an electrician are when I'm getting my but kicked. I really do hope it's the pushrod though. A win would be good about now. I played with the injection timing. ( meaning I was trying to watch when it pumped fuel while I was turning it) I didn't actually try to adjust anything. It looked petty right to me.

One more thing. The Rocker arms look discolored like they have gotten very hot. Is this pretty normal and should I be concerned? The pads where they push on the valve look good and except for the color change they look great.

 

[2Pbfeet]

Thank you again for the help. I'm hesitant to get to excited that's the problem but it sure does seem like the right disease for the symptom. I do like the new fuel lines. Would you take the head off and have a look or just put the new pushrod in and try it? The Yanmar book says not to go any further than you have to.

I'm not sorry it's taking so long. I'm way less intimidated by that motor than I was. I needed that. I'm learning tons. The times I've learned the most as an electrician are when I'm getting my but kicked. I really do hope it's the pushrod though. A win would be good about now. I played with the injection timing. ( meaning I was trying to watch when it pumped fuel while I was turning it) I didn't actually try to adjust anything. It looked petty right to me.

One more thing. The Rocker arms look discolored like they have gotten very hot. Is this pretty normal and should I be concerned? The pads where they push on the valve look good and except for the color change they look great.

I think it never hurts to get familiar with an engine that you might depend upon. I think that these Yanmar engines are neat engines, but that's me.

In general, I'm with the Yanmar manual; stop digging when you hit dirt.

That said, yes, I think that the valves got unburnt diesel and soot sprayed up by the valve guides by the looks of that, but it might also be some heat; how does the underside of the valve cover look? From here, the rocker arm contact surface looks ok, as I would expect. If it were me, I would be tempted to take a wire brush to the rocker arm to see if discoloration is superficial or not. Also, I would probably inspect (have a look-see at) the valve stem itself and the area around the top of the valve guide, without removing the springs. At this point, I haven't seen anything that would cause me to go as far as pulling the head, but other may see something that I missed.

Diesels are designed to burn lean, so even a little over fueling due to poor injection spray (e.g. air leak) can get them pretty hot pretty fast. The head and exhaust pipe looked ok from here.

All the best,

2PbFeet

 

[grywitt]

I think it never hurts to get familiar with an engine that you might depend upon. I think that these Yanmar engines are neat engines, but that's me.

In general, I'm with the Yanmar manual; stop digging when you hit dirt.

That said, yes, I think that the valves got unburnt diesel and soot sprayed up by the valve guides by the looks of that, but it might also be some heat; how does the underside of the valve cover look? From here, the rocker arm contact surface looks ok, as I would expect. If it were me, I would be tempted to take a wire brush to the rocker arm to see if discoloration is superficial or not. Also, I would probably inspect (have a look-see at) the valve stem itself and the area around the top of the valve guide, without removing the springs. At this point, I haven't seen anything that would cause me to go as far as pulling the head, but other may see something that I missed.

Diesels are designed to burn lean, so even a little over fueling due to poor injection spray (e.g. air leak) can get them pretty hot pretty fast. The head and exhaust pipe looked ok from here.

All the best,

2PbFeet

Your pretty smart. A little time with the brass wire brush and the discoloration all but disappeared.

 

[2Pbfeet]

Smart I don't know about; I think that I'm guilty of being a legend in my own mind, just before I do something really stupid.

However, "Been there, done that", makes up for a lot in my experience.

I'm glad to see that everything cleaned up nicely, without much effort, apparently.

All the best,

2PbFeet

 

[FarmingSmallKubota]

Just wondering if your vent fans are working on this unit. I ask because this is an air cooled engine and we talking about excessive heat and bent push rods.

 

[grywitt]

So I got the new push rods. They aren't the same by about 4mm. I decided to put them in and see if i even had that much adjustment. I do. They are at the very tip of the adjuster though. My problem is when I rotate the engine all the way around to tdc. At the combustion point if I rotate slowly the compression bleeds off and I can keep rotating. I can hear the air coming out. Is that normal? Should I continue to reassemble and hope it's carbon on the valve seats? I shouldn't be able to just push through right? At first I thought it was because I didn't have the injector torqued yet but that didn't stop it.

Well i tried it. It seemed to do better a bit. I got it to hold 3kw for a while. Kind of like that other day. I'm starting to think temperature is the factor for that success both times now. 3kw still is like it's over loaded smoke and Boggs. I was thinking carbon in the combustion chamber and it might be but now when I move the switch to stop the arm moves over to the magnet for a couple revolutions then let's go and starts running again. I didn't need with any of that stuff. Even after it's shut down if I move the arm to the magnet it would hold. Now if I push it over it pops off when I let go. Ugh ha ha. This thing. So much for the win.

I guess I need a better understanding of that governor and throttle system i don't know where the extra tension is coming from.

I was going to try sea foam and time to try and clean the combustion chamber but now I have this other issue.. the push rods seemed to work okay though and it was holding loads a little higher. I'll keep digging and send more pics when I do.

 

[2Pbfeet]

@grywitt If you can adjust the rocker arms, you should be ok. Part of the damage abatement on the push rods are that they compress, in addition to bending. Whether that was a design feature or happy accident, I don't know. Slow rotation of the crank won't achieve full compression, so that's normal in my book.

What altitude are you at in NM?
As @DieselAddict has pointed out elsewhere there is a very real altitude derate on non-turbo diesels;

Finally bought a MEP-831a

It was still smoking at 3kw load, it did sound better not running as fast as it was before. Tonight or tommrow ill set up electrinic gov. When I pluged the actuator back in and allowed it to control it wanted to surge. I change the tension and disatnce when i adjusted the plate so I expected...

www.steelsoldiers.com

on page 1-21 in the TM 9-6115-639-13&P manual, and on the machine itself. (10%@4000')

All the best, 2PbFeet

 

[grywitt]

@grywitt If you can adjust the rocker arms, you should be ok. Part of the damage abatement on the push rods are that they compress, in addition to bending. Whether that was a design feature or happy accident, I don't know. Slow rotation of the crank won't achieve full compression, so that's normal in my book.

What altitude are you at in NM?
As @DieselAddict has pointed out elsewhere there is a very real altitude derate on non-turbo diesels;

Finally bought a MEP-831a

It was still smoking at 3kw load, it did sound better not running as fast as it was before. Tonight or tommrow ill set up electrinic gov. When I pluged the actuator back in and allowed it to control it wanted to surge. I change the tension and disatnce when i adjusted the plate so I expected...

www.steelsoldiers.com

on page 1-21 in the TM 9-6115-639-13&P manual, and on the machine itself. (10%@4000')

All the best, 2PbFeet

We are at 3000 feet here

What would cause the extra tension on the magnet so the machine won't shut off now? I did it several times and it will start to shut off then release the magnet and keep running?

 

[2Pbfeet]

We are at 3000 feet here

What would cause the extra tension on the magnet so the machine won't shut off now? I did it several times and it will start to shut off then release the magnet and keep running?

In my book, that altitude is probably good for a ballpark 10% derate.

If it were me, I would check the manual; IIRC, there's an adjustment procedure.

All the best, 2PbFeet

 

[grywitt]

I'll tinker with that. It could be many things. Heck it's starting to shut down then it pops it out and gets going again. I would think electrical maybe a loose connection but with the machine off and the batteries not connected i could always just push the arm over to the magnet and it would hold. Not now so I'm thinking there is extra tension on that arm now.

In my book, that altitude is probably good for a ballpark 10% derate.

If it were me, I would check the manual; IIRC, there's an adjustment procedure.

All the best, 2PbFeet

I'll do that. Also I'm sure all the carbon that wasn't going out in each stroke because the valves weren't opening all the way must be needing cleaned, burned out or something. Like @DieselAddict said in that post you shared. I'll keep reading and tinkering. Thank you again for the info and ideas.

 

[Guyfang]

Take a picture of the linkage unpowered, and powered up.

 

[grywitt]

Powered with no load? It's weird right now i don't know if I accidentally bent the linkage or something. The magnet won't hold the arm in the closed position even with the power off. It always did before. I learned a lot about the mechanical governor because I moved the spring all the way over close to the pivot point so the magnet would hold but then the revs were wrong from not enough spring tension to fight the weights so it wouldn't keep revs up high enough. I put the spring back in the original position and decided to just run the machine under load to try and burn out any carbon.

Right now it's at about 3 hours at 2.8kw. I think it wont hold the off position still but haven't tried again. I will get the pics though. So not running but not touching the magnet either? Running no load? I'll get one running at 2.8kw just because I can also.

 

[grywitt]

Take a picture of the linkage unpowered, and powered up.

Here is running with 2.8kw and running no load. I didn't shut the machine off to get one with no power machine not running. The no load Pic does still have the contactor engaged but the load bank was at zero. It is smoking less now than it was the first couple hours.

 

[grywitt]

Here is a video of it blowing black smoke then clearing up then the same a few times. I honest didn't expect it to choke and kick out because it had been running like that quite a while but I caught it dropping the load i believe just from to low of rpm. It ran about 3 hours at 2.75kw then I went out to take a couple pics and reset it to 2.75. Went out to check idk 45 min later and it was running unloaded. Set it up again came out to check again after lunch and this video shows that check. I guess there is one other in there where it seemed to be running pretty good and minimal smoke at 2.75 so I tried 3kw. She fell on her face quicker than I could open switches to stop it. I am running it at 2.5kw now just for the loaded hours. It is pretty hot today now to so I'm sure that's affecting it. Just an update with video.

I did do an oil change this morning before I started it and put 6oz of marvel mystery oil in with it. Also I checked valve lash while it was cold. I also pulled the injector and put some sea foam in the cylinder to soak for a while before I ran it. Running no load I am 5/16 gap. I am running on the governor board that kloppk made. The Gen seems petty decent but not quite right. I think I've never ran another of the same. Even with derating 300 watts for 3000 feet elevation it seems not quite there. For now I'll keep running loaded and hopefully burning out carbon. If any one has suggestions I'm open. Thanks for the support.

 

[grywitt]

Take a picture of the linkage unpowered, and powered up.

This is the pic with it shut off. When I turn the switch to off it goes over to the magnet for a couple seconds then it let's it go and it keeps running. If you turn the switch to run it revs up Settles in and then if you switch to off it repeats. This is a new problem And I've tried the things the TM says to try. My actuator is 10 ohms I've adjusted my linkage. I can't figure out what changed. I'm not done looking though.

 

[grywitt]

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The long one i shut the gen down in the last 30 seconds so you can see how it acts. Also it's a couple minutes of it running no load after 6 hours loaded. The short one is the magnet not holding

 

[kloppk]

I see in the pics and videos that somewhere in it's life someone cut the safety wires off the two mechanical governor adjustments. Not good... Those are adjusted at the factory and normally would not ever be messed with. Someone messed with those adjustments.
In the short video the governor arm does not stick to the magnet causing problems with not shutting down properly. My hunch is that someone messed with the strength of the magnet and now it's not strong enough.
The magnet strength can be adjusted. If you loosen the nut securing it to the bracket you can rotate the magnet inside the round collar to move it closer to the collar opening to make it stronger.
The magnet strength has to be set strong enough for the arm to stick to it at shutdown but no so strong that the Governor Controller can't pop it off the magnet at startup.

Is the rod adjusted so the gap is set to 5/16" running at no load?