I appreciate the comments. I'll pull the injectors tomorrow and see if I can find a local place to test them next week. Or, does anyone have a place they recommend that I could mail them? I don't really know where to send them.
Odd Colored Piston Head
- Thread starter jetattblue
- Start date
I agree that #2 appears to be the only normal cylinder. #3 looks like the cylinder liner is marked, Drop the piston in #3 to the bottom of the stroke and take a photo. Can you feel any imperfection in the cylinder liner with your fingernail?
When it ran, was it knocking? I am betting this is a ether damaged motor and may have some bent rods.
When it ran, was it knocking? I am betting this is a ether damaged motor and may have some bent rods.
Here's a place I'd recommend for new injectors. You might call them to ask about rebuilding, but with shipment it may not be worth it.
Do a Google search for "injection pump service" and see if you can find someone nearby for just cleaning. I have a nearby injection pump shop and I have taken injectors there (on a scheduled time) and they have never charged me for testing.
Ask the shop what the charges will be for testing and compare that with new, then decide.
Do a Google search for "injection pump service" and see if you can find someone nearby for just cleaning. I have a nearby injection pump shop and I have taken injectors there (on a scheduled time) and they have never charged me for testing.
Ask the shop what the charges will be for testing and compare that with new, then decide.
North Idaho Wolfman, your approach was dead on - I was thinking about things backwards. I think Piston 2 is the normal one, and the others are off-colored. Here's why:
This morning, I continued breaking things down by removing the pistons. I am hopeful to keep the crankshaft, etc in place, so I removed them with crankshaft in place by accessing everything underneath; the engine has been removed at this point. Piston 2 looked fine to me upon removal.
I am not sure how pistons are numbered, so I'll identify them by Front (closest to the fly wheel on a BX1800) and Back (closest to the fan, belt, etc.). Next, I removed the Back Piston; it seemed to slide out with the same amount of effort/tension as Piston 2. The rod appeared straight, etc. But, when I barely moved the middle ring with my finger, the ridge on the piston between the oil ring and the middle ring crumbled - about an 1/8 of an inch just broke out. The same thing happened with the Front Piston on the same ridge. Additionally, the thicker piston ridge between the top and middle rings on the Back Piston has cracks in it as if it is about to crumble, too.
Although I am very new at this, everything else appeared normal to me. First, the cylinder bores all looked uniform with - surprisingly - no scratching or gouging or pitting. I am going to measure them later this week. Second, the piston assemblies all looked good to me - no bent rods, the wrist pins all moved with the same ease. In other words, at least visually, everything appears equal except the black color of the tops of the Back and Front pistons, and the cracks in the Back and Front Piston ridges.
The most I was told about this engine is "low compression" on the middle cylinder - which doesn't necessarily appear correct, and that the engine was not maintained by the previous owner. The engine has a little over 500 hours on it, and the tractor looks fine other than it appears to have been "stored" outside for its entire life. Again, I got this tractor - along with an L2550 - for a great deal, and I am really enjoying this process. This is not a money making proposition for me; it's a fun way to learn about these engines.
Any ideas on next steps or causes of these issues? I am definitely going to have the injectors tested or replaced. I'll need to purchase new pistons/rings (after measuring of course) and re-assemble without having to remove the crankshaft if possible.
This morning, I continued breaking things down by removing the pistons. I am hopeful to keep the crankshaft, etc in place, so I removed them with crankshaft in place by accessing everything underneath; the engine has been removed at this point. Piston 2 looked fine to me upon removal.
I am not sure how pistons are numbered, so I'll identify them by Front (closest to the fly wheel on a BX1800) and Back (closest to the fan, belt, etc.). Next, I removed the Back Piston; it seemed to slide out with the same amount of effort/tension as Piston 2. The rod appeared straight, etc. But, when I barely moved the middle ring with my finger, the ridge on the piston between the oil ring and the middle ring crumbled - about an 1/8 of an inch just broke out. The same thing happened with the Front Piston on the same ridge. Additionally, the thicker piston ridge between the top and middle rings on the Back Piston has cracks in it as if it is about to crumble, too.
Although I am very new at this, everything else appeared normal to me. First, the cylinder bores all looked uniform with - surprisingly - no scratching or gouging or pitting. I am going to measure them later this week. Second, the piston assemblies all looked good to me - no bent rods, the wrist pins all moved with the same ease. In other words, at least visually, everything appears equal except the black color of the tops of the Back and Front pistons, and the cracks in the Back and Front Piston ridges.
The most I was told about this engine is "low compression" on the middle cylinder - which doesn't necessarily appear correct, and that the engine was not maintained by the previous owner. The engine has a little over 500 hours on it, and the tractor looks fine other than it appears to have been "stored" outside for its entire life. Again, I got this tractor - along with an L2550 - for a great deal, and I am really enjoying this process. This is not a money making proposition for me; it's a fun way to learn about these engines.
Any ideas on next steps or causes of these issues? I am definitely going to have the injectors tested or replaced. I'll need to purchase new pistons/rings (after measuring of course) and re-assemble without having to remove the crankshaft if possible.
Your description of the piston crumbling sounds like the previous owner used ether to get it started.
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Newlyme
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M4900 w/loader, finish mower, tiller, auger, rake. BX24 w/loader, backhoe
Just a thought here.
You have taken this engine almost all of the way apart and are finding out what you were told was not the case. It sounds like you are going to be putting some money into it. I certainly understand the learning and the, for fun, not profit aspect. Why not do a complete tear down and inspection along the way to be sure on the completion that you have found all of the problems. You certainly have a lot of knowledge here to guide you along the way.
Looking forward to reading the story through the journey.
Good luck.
You have taken this engine almost all of the way apart and are finding out what you were told was not the case. It sounds like you are going to be putting some money into it. I certainly understand the learning and the, for fun, not profit aspect. Why not do a complete tear down and inspection along the way to be sure on the completion that you have found all of the problems. You certainly have a lot of knowledge here to guide you along the way.
Looking forward to reading the story through the journey.
Good luck.
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Check your main bearings visually and then invest in some Plastigage (cheap) to check the tolerance. I would bring the head to an engine machine shop and have them go through the valves and do a magnaflux on it.
North Idaho Wolfman
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A full Kubota rebuild kit should run about $800 and will give you all the bearing, seals, pistons, rings, gaskets and misc parts to do a complete rebuild.
I highly recommend it, I just got done doing a full rebuild on a D850 and it's not that hard to do.
It get rather pricey if you have to do liners and machine work, so I hope you can skip that.
I highly recommend it, I just got done doing a full rebuild on a D850 and it's not that hard to do.
It get rather pricey if you have to do liners and machine work, so I hope you can skip that.
North Idaho Wolfman
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Pull a rod or main bearing and post a picture of it, I'll bet they are fine, kubota's are very easy on bearings.
These little engines have a LOT of compression! They have to. The smaller the engine, the less air that's in the cylinders, means it needs all the help it can get to self-sustain being that there's no spark to ignite.
Some of the newer 782's have a cranking compression of up around 700 psi if that tells you anything. 722's should be 500+.
Center cylinder is usually the one to get damaged first on an overheat, hence if I see one with a low compression pressure on middle cylinder of a 3 cylinder engine, I look real closely for signs of overheating, which usually means pulling the pan, then pop the pistons out of the block. Inspect cylinders really good. Inspect pistons very well.
Ether. Great way to destroy a kubota diesel. Any diesel for that matter. The old GM 2 strokes were a little different but those are gone from memory, thank goodness. On Kubota 722's and 782's and 902's and 1102's and, well you get the idea, use of ether commonly (at least in this area) will break ring lands, and if they aren't broken, the rods will be bent. Easy way to know if rods are bent is to roll each cylinder to true TDC, then grab a depth gauge and measure how far each piston is out of the top of the cylinder. They all "pop up" a little bit. If one is significantly "deeper" than other others, you found a bent rod most likely (assuming there was no bottom end noises). Or just pull the pan and pop the pistons out, taking care of noting which way they came out (fore and aft) as well as which cylinder they came out of, so that they can be reassembled the same way. Also if you have to replace a rod, take note of how it's oriented with the piston so you can install the new one the same direction. I had a call earlier from someone who says that they have coolant leaking from between the head & block on an MX5000. I asked them if ether was ever used, he says every time he starts it because the glow plugs don't work. Glow plugs are an easy fix. Replacing a head gasket isn't-and that's assuming that it's just the gasket. It's possible that the head has been lifted off of the block, stretched bolts. Wouldn't be the first time I seen it, although normally it just bends the rods.
Some of the newer 782's have a cranking compression of up around 700 psi if that tells you anything. 722's should be 500+.
Center cylinder is usually the one to get damaged first on an overheat, hence if I see one with a low compression pressure on middle cylinder of a 3 cylinder engine, I look real closely for signs of overheating, which usually means pulling the pan, then pop the pistons out of the block. Inspect cylinders really good. Inspect pistons very well.
Ether. Great way to destroy a kubota diesel. Any diesel for that matter. The old GM 2 strokes were a little different but those are gone from memory, thank goodness. On Kubota 722's and 782's and 902's and 1102's and, well you get the idea, use of ether commonly (at least in this area) will break ring lands, and if they aren't broken, the rods will be bent. Easy way to know if rods are bent is to roll each cylinder to true TDC, then grab a depth gauge and measure how far each piston is out of the top of the cylinder. They all "pop up" a little bit. If one is significantly "deeper" than other others, you found a bent rod most likely (assuming there was no bottom end noises). Or just pull the pan and pop the pistons out, taking care of noting which way they came out (fore and aft) as well as which cylinder they came out of, so that they can be reassembled the same way. Also if you have to replace a rod, take note of how it's oriented with the piston so you can install the new one the same direction. I had a call earlier from someone who says that they have coolant leaking from between the head & block on an MX5000. I asked them if ether was ever used, he says every time he starts it because the glow plugs don't work. Glow plugs are an easy fix. Replacing a head gasket isn't-and that's assuming that it's just the gasket. It's possible that the head has been lifted off of the block, stretched bolts. Wouldn't be the first time I seen it, although normally it just bends the rods.
Friends don't let friends use ether.
Ah yes, GM 2 strokes. I had a long love/hate relationship with them back in the '70s and early '80s.
We had a Marion dragline with a 3-71. We put a LOT of hours on that machine. Once it got to around 12,000 hours, if it wasn't hot and the ambient temperature was below 80°F, you had to use ether to get it started. Still had lots of power though.
Don't ask about using ether to get the beads on truck tires to seal.
Re: Odd Colored Piston Head - Pic Added on 2nd Page
Just had to add that I appreciate the fact that you bought a project machine and
1. You’re actually working on it. I generally don’t buy projects because I don’t have the time.
2. You’re diving right into and learning
I look forward to seeing it running again and enjoy learning stuff through your project. Good luck!
Just had to add that I appreciate the fact that you bought a project machine and
1. You’re actually working on it. I generally don’t buy projects because I don’t have the time.
2. You’re diving right into and learning
I look forward to seeing it running again and enjoy learning stuff through your project. Good luck!
Re: Odd Colored Piston Head - Pic Added on 2nd Page
I really appreciate the encouragement! This is totally new ground for me, but I'm enjoying the ride.
I really appreciate the encouragement! This is totally new ground for me, but I'm enjoying the ride.
Pau7220
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Alright. For the first time, I used a micrometer and dial bore gauge to measure my cylinders. I used the measuring strategy from the workshop manual - measuring at 3 different depths in the cylinder and taking 2 perpendicular measurements at each level.
Factory spec. is between 2.63779 to 2.63854. I do not have the tools that measure that far, but I can measure to the 10 thousandths. None were within factory specs, but they all fell well within the allowable limit of 2.64444.
The middle cylinder had the undamaged piston, and it measured the closest to spec with the largest measurement being 2.6390 and the smallest being 2.6387; the max out of round was .0003 on the middle.
The front cylinder had a damaged piston, and it measured 2.6391 at the largest and 2.6382 at the smallest; the max out of round was .0009 and it occurred at the deepest level, i.e. closest to the bottom of the cylinder.
The back cylinder also had a damaged piston, and it measured 2.6392 at the largest and 2.6384 at the smallest; the max out of round was .0007 and it occurred at the deepest level.
Based on these measurements, my plan was to lightly hone the cylinders at this point and replace the pistons, rings, and connecting rod bearings. What do you think?
Factory spec. is between 2.63779 to 2.63854. I do not have the tools that measure that far, but I can measure to the 10 thousandths. None were within factory specs, but they all fell well within the allowable limit of 2.64444.
The middle cylinder had the undamaged piston, and it measured the closest to spec with the largest measurement being 2.6390 and the smallest being 2.6387; the max out of round was .0003 on the middle.
The front cylinder had a damaged piston, and it measured 2.6391 at the largest and 2.6382 at the smallest; the max out of round was .0009 and it occurred at the deepest level, i.e. closest to the bottom of the cylinder.
The back cylinder also had a damaged piston, and it measured 2.6392 at the largest and 2.6384 at the smallest; the max out of round was .0007 and it occurred at the deepest level.
Based on these measurements, my plan was to lightly hone the cylinders at this point and replace the pistons, rings, and connecting rod bearings. What do you think?
North Idaho Wolfman
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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more