A few comments about my on-going experience with my "failed" Kubota

[texasgeezer]

Recently purchased a Kubota L2250 4wd d1302 engine. Under cover, 1050 hours, 5' tiller, finish mower, post hole digger, brush hog, box blade for $5000. Thought it was a good price for a quoted 'it is a good tractor'.

After replacing battery, started & run smooth, good power, no smoke.

Started to drive it home (about two miles). Gauge indicated it was above mid-line in temperature (did not boil), turned around, parked it, & started to check it for overheating cause. Also noticed power steering didn't appear to be working.

Found radiator plugged with dirt-dobber nests. Water pump bearing worn, massive corrosion of aluminum gear case cover & thermostat housing. Hydraulic pump with internal bushing & shaft broken. Exhaust manifold cracked. Found fuel pump was not pumping (just allowing gravity flow).

Replaced those with new & good used parts. Pulled the head & had it checked & (they rebuilt it, didn't check it).

Pulled 'drive shaft for front axle & axle pivots (corrosion starting). Drilled a tapped a couple of holes in pivots for grease zerts.

Put everything back together & it started & ran smooth, good power, no smoke. Noticed very slight 'knocking sound' at low rpm. Sound would go away at higher rpm's. Pulled injectors & had them tested. All failed, with slight 'dribbling' & 'popping off' too soon. Told to run with a diesel additive for injector cleaning for a few hours. Ran about five hours good power, but no change in sound.

Purchased & installed 3 new injectors. No change in sound. After running for about an hour longer, pulled oil pan, head, rods & pistons. Bearings showed no apparent wear but #2 cylinder's piston was slightly scuffed and rings would not move as they should. Cylinder wall was slightly scuffed.

Have been told it was most likely due to the injectors releasing too much fuel and washing the oil off of piston & cylinder wall. Also, possible diesel contamination of engine oil because of failed fuel pump.

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My thinking is that even though your tractor is running good, it wouldn't hurt to check your fuel pump (see if it will suck diesel from a container on the floor & have the engine run okay).

Pull the injectors & have them checked for proper operation (shop near me checks them free). New injectors cost me about $300. Easy to install.

If you are 'gaining' oil, maybe your fuel pump is letting diesel into the crankcase & diluting the oil. New pump about $65.

Always keep your coolant system in top condition & check both sides of radiator for blockages. About $225 for radiator cleaning, water pump, new hoses, & thermostat.

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My rebuild will cost $5000 if I let Kubota or other shops do all the work. If I do most of the labor it will cost about $2000 in parts & machine shop charges.

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I've spent several days researching the engine failure & how to reduce chance of failure again.

So far planning on making inner cylinder (#2) about .0005 inches bigger than outer cylinders. (industrial Kubota engine supposedly has smaller piston)

Also having the new pistons coated by 'Calico, Swain-tech, or another 'reputable' company. Supposed to reduce friction, expansion due to heat, & cool piston better from engine oil.

Plan to do thorough cleaning of machine shop work & to use a finer hone than normal to reduce cylinder wear during 'break-in'. (apparently cross hatch pattern is worn off during break-in & more metal particles end up in the engine oil with more coarse hones).

 

[Eric McCarthy]

WOW!! Well I'm quite impressed with your fixing and repairs. It sounds like you know what you're doing and are not cutting corners doing so! It sounds to me that the previous owner didnt do a thing to the tractor other then just operate it an ran it into the ground. Doesnt even seem like they changed a single drop of fluid.

 

[bcbull378]

Im thinking next time you buy used equipment you may want to put it thru a a serries of test, like a test drive save yourself a lot of problems

 

[MagKarl]

So you bought a 20+ year old tractor, and it ran good with no smoke, but had a slight knock at idle? Who or what was the failure?

 

[Bluegill]

Interesting and useful information. Good learning experience!

 

[Kytim]

How did you hear or notice the "slight knock" over the normal sound of a small diesel engine?

 

[texasgeezer]

With the exception of 'magkarl', thanks for the comments. Magkarl, if you bend way over & look up, you might get a good picture of the way you come across. Magkarl, it is not normal to disassemble a tractor before buying it. The dirt dobber nests were behind the grill & not visible. Fuel knocks are common.

What the old guy didn't say is that he didn't really know anything about the tractor, his wife told me later that her husband didn't know anything about it & should not have told me it was a good tractor. He had never driven it. It was her father's. What he should have told me is that it had sat for five years (under cover) without being started.

Fuel knock is quite common with diesels & probably contribute to a shorter life due to the slight or excessive loading. The engine runs good & with good power. It is likely most people don't realize the importance of even a 'low' level knocking sound.

Also & I believe (probably for most if not all diesels), that the excessive heat caused by fuel knock will damage the glow plugs & can cause their tips to melt & fall off into either the pre-combustion chamber or on top of the pistons. This will lead to a blown engine if the tip is not retrieved before it gets into the cylinder.

It used to be that diesel fuel also acted as a lubricant & any excessive fuel probably didn't hurt the pistons or their rings. The newer diesel fuel provides virtually no lubrication ability.

Most diesels make a little bit of a knocking sound, one dealer service manager & another shop's main diesel tech said it probably was from injector(s) releasing too much fuel - too soon. Another service manager said 'all small engine' kubota's make a slight knocking sound. The 'slight' knock would go away at rpm's above 1000.

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I'm just trying to make people aware of how to minimize problems that can lead to excessive repair costs. Such as:

Good anti-freeze 'preferably long haul fleet type' with good cavitation additives (changed or checked periodically).

Change coolant hoses & water pump belts periodically.

Use a good proven additive in the diesel fuel. Lucas is not a good one unless they have changed their formula. Power Service is fairly low on improving lubricity. (based on lubricity tests)

Don't use bio-diesel if it is not going to used within (a month). Too many algae & water problems.

Check for radiator blockages (on both sides) don't just clean the screen.

Check your fuel pump periodically (can put diesel into the engine oil & causes a little more strain on the injection pump if not working) On tanks that don't flow by gravity it can cause much earlier injection pump failure.

I will probably add a 2 micron fuel filter if I can find a small one. (To try to reduce injector problems & injection pump wear).

These are all relatively low cost things compared to a $5000 engine rebuild.

 

[hodge]

With the exception of 'magkarl', thanks for the comments. Magkarl, if you bend way over & look up, you might get a good picture of the way you come across. Magkarl, it is not normal to disassemble a tractor before buying it. The dirt dobber nests were behind the grill & not visible. Fuel knocks are common.

What the old guy didn't say is that he didn't really know anything about the tractor, his wife told me later that her husband didn't know anything about it & should not have told me it was a good tractor. He had never driven it. It was her father's. What he should have told me is that it had sat for five years (under cover) without being started.

Fuel knock is quite common with diesels & probably contribute to a shorter life due to the slight or excessive loading. The engine runs good & with good power. It is likely most people don't realize the importance of even a 'low' level knocking sound.

Also & I believe (probably for most if not all diesels), that the excessive heat caused by fuel knock will damage the glow plugs & can cause their tips to melt & fall off into either the pre-combustion chamber or on top of the pistons. This will lead to a blown engine if the tip is not retrieved before it gets into the cylinder.

It used to be that diesel fuel also acted as a lubricant & any excessive fuel probably didn't hurt the pistons or their rings. The newer diesel fuel provides virtually no lubrication ability.

Most diesels make a little bit of a knocking sound, one dealer service manager & another shop's main diesel tech said it probably was from injector(s) releasing too much fuel - too soon. Another service manager said 'all small engine' kubota's make a slight knocking sound. The 'slight' knock would go away at rpm's above 1000.

-----------

I'm just trying to make people aware of how to minimize problems that can lead to excessive repair costs. Such as:

Good anti-freeze 'preferably long haul fleet type' with good cavitation additives (changed or checked periodically).

Change coolant hoses & water pump belts periodically.

Use a good proven additive in the diesel fuel. Lucas is not a good one unless they have changed their formula. Power Service is fairly low on improving lubricity. (based on lubricity tests)

Don't use bio-diesel if it is not going to used within (a month). Too many algae & water problems.

Check for radiator blockages (on both sides) don't just clean the screen.

Check your fuel pump periodically (can put diesel into the engine oil & causes a little more strain on the injection pump if not working) On tanks that don't flow by gravity it can cause much earlier injection pump failure.

I will probably add a 2 micron fuel filter if I can find a small one. (To try to reduce injector problems & injection pump wear).

These are all relatively low cost things compared to a $5000 engine rebuild.

You sound like you know what you are talking about, and have offered lots of good info and advice.
Maybe Magkarl rubbed you wrong, but your response is just as out of line. People on this forum don't typically speak to each other that way- just look around, and see for yourself. There are good folks here, treating each other with respect and with dignity.

 

[MagKarl]

Nice. You're a real class act geezer.

I still don't see any Kubota failure, just a 20+ year old machine that needed to be caught up on the maintenance. Yes, that's the same thing I posted before.

Move on, accept the fact that you bought a whole bunch of impliments and a tractor for a song. Accept that old gear, even high quality stuff like Kubota's, needs upkeep. When you get a sweet deal, you have to expect to do some. You didn't check things out too carefully, you didn't investigate the history, you threw parts at it, and now you tore it down and it's going to cost a lot to put back together. You sound like you're looking for anyone else to blame. Put it back together and move on. Trade it in on a new one with a warranty and absolve yourself of any and all responsibility.

 

[bcbull378]

Nice. You're a real class act geezer.

I still don't see any Kubota failure, just a 20+ year old machine that needed to be caught up on the maintenance. Yes, that's the same thing I posted before.

Move on, accept the fact that you bought a whole bunch of impliments and a tractor for a song. Accept that old gear, even high quality stuff like Kubota's, needs upkeep. When you get a sweet deal, you have to expect to do some. You didn't check things out too carefully, you didn't investigate the history, you threw parts at it, and now you tore it down and it's going to cost a lot to put back together. You sound like you're looking for anyone else to blame. Put it back together and move on. Trade it in on a new one with a warranty and absolve yourself of any and all responsibility.

Good call Magkarl I like a fella that calls it the way he sees it I couldnt agree more, used equipment is used equipment. Ive bought new and used and there are hidden dangers in all you buy , if a deal is to good to belive its normally is.....Dan

 

[texasgeezer]

Interesting how people assume things & read into to it what they want then make comments fully intended to inflict 'harm' by bullying someone that they know nothing about. Also interesting how others join in and support the comments. Would not have liked to have been in school with them.

It seems a few of you are concentrating on my 'purchase of the tractor' and my 'failure' as a person, instead of commenting about what might have contributed to the requirement for expensive repairs.

If you go back and read what I first posted and then read Magkarl's comment about 'who or what' is to blame. I believe you might see Magkarl's comment was uncalled for.

I said it ran smooth, good power, no smoke. That's what a tractor should do.
No reason not to purchase it and would do it again. That is why I made the comment about Magkarl.

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If you read my comments, the 'slight knocking' didn't come about until after I fixed the cooling, power steering, had the head checked & rebuilt, power washed twice and put back together. That was about three months after I purchased it.

At that time there was no cylinder scoring that was visible on the cylinder walls. I didn't pull the pistons to check the rings or rod bearings at that time. I don't think many people would. The tractor still ran smooth with good power when I decided to pull the pistons to check the rod bearings. I didn't expect to find the start of a piston/ring failure. I do not know that this 'slight' wear was causing the 'light knock' that I was hearing. It could still be a crank bearing, piston slap, or maybe just the way it sounds. I had two service managers (one Kubota & one John Deere) tell me a 'little knocking' was normal. I just didn't want a rod bearing getting worse if that was the cause. Not much expense to check it out, mostly just my time.

So either the 'hot' condition (not boiling) damaged the piston/rings or the fuel injectors failing probably caused the problem. I believe the fuel injectors probably washed the cylinder. Looking back I should have replaced the injectors immediately & not tried the 'injector cleaner'. That is the point I was hoping to make.

I made the comment about the pistons to make people aware that Kubota knew they had to 'change' the pistons on the IDI type industrial engines to make them more reliable. Most farm tractors never approach the extreme loading that industrial engines endure. I think that if you are going to rebuild a DI engine then maybe a smidgen of extra clearance on the inner cylinders might not be such a bad thing (if the equivalent IDI version has two part #'s).

I made the comment about the fuel pump because I believe most people would assume the fuel pump was working because the engine was still running. If it is not working, the fuel injection pump must work harder, even with the gravity flow. Also some failures would allow diesel fuel to get into the oil.

I made the comments about 'fleet' type antifreeze because a lot of people don't realize that the anti-freeze formula can provide much better protection for corrosion and wear caused by cavitation. Cavitation can damage the water pump as well as the inner part of cylinder walls. The early 7.3 Ford/International engines failed at about 100,000 miles due to cavitation. Ford knew of the problem, but most dealers never made the owners aware of that fact.

I made the comments about glow plugs because I had a Chevrolet dealer replace a bad injector & never replaced the glow plug. The tip fell off & blew that cylinder. I didn't know glow plugs could be damaged that way.

I made the comments about 'honing' because I believe 'based on my research' that the typical honing done by machine shops is too aggressive.
My findings indicate that the honing pattern will be worn off as the engine is run. This wear increases the cylinder size, puts metal particles into the oil, and decreases the life of the engine. My findings (U of Michigan study) also indicate that if the cylinders are in good condition (smooth & within spec's) that honing will remove a protective layer that has been built up over the life of the engine. This layer appears to provide a 'dry lubricant' quality to the cylinder walls. I believe that most machine/rebuilding shops put engines together without studying what changes they could make to improve the engines life. The ones I've checked with use the same grit hone for 'all engines'. Some don't use sealants, they just use gaskets.

I made the comment about trying to find a 2 micron fuel filter because the standard filter is, I believe 12 micron. Better fuel filtering might reduce injector 'dribbling' and 'popping off' too soon.

Hopefully the majority of readers can see what I'm intending. I don't mind sharing comments that are meant to provide good advice.

I've learned some of these things by my mistakes, some created by others, and some things by doing a tremendous amount of studying & looking for information. If there are other comments about how to possibly increase engine life I would like to know them.

 

[Eric McCarthy]

Well I for one feel smarter just reading his post and learning alot more about engines that I never knew before.

 

[hodge]

Well I for one feel smarter just reading his post and learning alot more about engines that I never knew before.

I agree with Eric. I never questioned your information, texasgeezer, or your expertise. It sounds like you know what you are talking about, through experience and research. I commented because you're the new guy- you don't know folks yet, or how they say things. It is inappropriate to get pissy like that, whether right off the bat, or once you have settled in. Most folks here don't treat each other that way. And, if that is simply how you are- some people believe that they can say what they want, and it's your problem how you take it- then you have the right to be that way. But, I am not that way, I don't speak to others that way, and it is my right to speak up and say that it isn't appreciated. Now, that doesn't mean that a person isn't welcome here- we have seen some others come and go because they got bent out of shape when they showed attitude and was called on it. A difference of opinion is no reason to throw in the towel. It just means that, like in any type of relationship, you have to learn what boundries are appropriate. It isn't that I don't have a tough skin- I'm a Christian. I'm used to ridicule and disrespect. But, I chose civility and respect. It's a good way to live.

 

[Apogee]

Texasgeezer,

I'm sorry that you've run into the issues with the tractor that you bought. It's a bummer. It's also too bad the seller wasn't more forthright with what he knew about it and his overall lack of knowledge. At least you're lucky that you've got the experience to be able to get it properly handled. Once all is said and done, you'll have a very nice unit and you'll know where it stands from a baseline standpoint. Hopefully this experience doesn't diminish your view of Kubota in general, as I think you'll be impressed once the lack of maintenance bugs all get worked out of your little beauty.

I appreciate the info that you've shared regarding your finds and also the proposed fixes. Should be useful in the future as I have several units to rebuild.

My hope is you will choose to stick around as there is much that I can learn from your posts. It will also be nice to eventually see pics of your tractor and what you plan to use it for.

In the end, besides the hassle factor, from an expense standpoint I think you'll come out okay. Yes these things are expensive to repair, but once finished you'll have a unit with a new engine that should last a long time. Further, the total package cost will still be about a third the cost of buying new if you also factor in the implements. Hopefully it goes back together smoothly so you get to enjoy your orange beast as originally intended.

Thanks again for the info!

Good luck,

Steve

 

[Bluegill]

This ("failed" Kubota) in the title might have been part of the cause.

'Failed maintenance' of said Kubota might have eased tensions...

But you did cover that too...

Tex, I do appreciate the good info!