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Post by 69Rebel on Dec 5, 2019 22:42:20 GMT -8
Well, in the interest of expanding my capabilities in the field of hole digging, I plunked down a fairly large pile of $$ for a newer excavator. A 2012 Takeuchi TB138FR equipped with a Yanmar 3TNV88 non-turbo engine. After spending a day or two of taking care of the deferred maintenance, it has occurred to me that this engine lacks power. It "bogs" when using multiple functions simultaneously, and produces absolutely no black smoke. Ever. Fuel starvation? I went through the fuel system from stem to stern, blowing out fuel lines, cleaning the separator, replacing the main cartridge filter, replacing the lift pump and so on. No joy. The controls and hydraulics feel very good. Smooth and precise. The pump isn't screaming cavitation. It doesn't stall, but the way it grunts with no smoke kinda bothers me. Did Tak really engineer it this way? Is the governor wonky perhaps? Emissions standards? It's not a tier 4 system. My old machine that I just sold off would go into bypass without even slowing down despite having a considerably smaller, and more primative powerplant. Should I learn to live with it? Can I goose the governor a little? Is there a diesel expert in the house?
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Post by spud on Dec 6, 2019 16:45:53 GMT -8
Yaknow i’m a diesel mechanic. Never worked on a yanmar. I have worked on many a perkins, kubota, and shibarus. ( ISC’s) and of course theres my main thing caterpillar. You sound like you know what your up to. Lack of smoke generally means lack of fueling, most everything will make some haze when it gets loaded down. Can you post a few pics of the engine fuel system? It may be low on fuel pressure. Clean exhaust means its not restricted for air.
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Post by 69Rebel on Dec 6, 2019 17:27:30 GMT -8
I changed out the air filters, so no restrictions there. I'll shoot a pic of it tomorrow in the daylight.
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Post by 69Rebel on Dec 7, 2019 14:36:04 GMT -8
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Post by spud on Dec 7, 2019 17:50:31 GMT -8
Yep. I dont know shit about that pump. Its a 3 cylinder rotary deal. If it aint smokin you know its making good injection pressure, timing and atomization. If it lacks power it may be missing volume. I suggest making sure it gets full throttle travel. I know you have already been thru the fuel supply system but it would be a good idea to verify supply pressure. One bad idea i can think of is engine speed. You have a tamperproof screw you tamper with for a little more rpm... that normally equates to more hp. The idea of the governor is it adds fuel as rpm lugs down at rated rpm, to try and power up to maintain that rpm. If it is dropping revs as load is applied with no increase in exhaust haze... its either very combustion/ emission efficient or its not boosting fuel delivery, in my opinion. If it lugs down some but works the load well i would assume its doing ok. Hydraulics can be a heavy load if multitasked. Also you might have good engine torque but a hydraulic problem causing excess loading. Normally a diesel will smoke when its asked too do work its not rated for. So to keep a log winded tale real, i dont know anything specific. Yanmar and yanmar owners may be a better resource to explore. Google time? I agree generally, no smoke? Hmmm. No haze? Bigger hmmm. Some of the little n/a diesels like the ISC & kubota do have advanced combustion efficiency, but still haze under load.
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Post by spud on Dec 7, 2019 18:06:29 GMT -8
Claims 28 kw power at 3000 rpms. That suggests this engine will tolerate hi revs...What is your rpm?
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Post by 69Rebel on Dec 7, 2019 18:18:25 GMT -8
It has no tach, but I don't think it's spinning 3K. I did adjust the throttle a little to get to at least come against the high speed stop. It seems to recover well when working. Interestingly, it doesn't bog much at all at low rpm, just a work RPM. Aside from the bog, it runs sweet. Fires right up on cold mornings, and runs smooth and nice, so I'm inferring that to mean that the injector pressure and timing are adequate. The hydraulics don't seem janky, they are very smooth, precise, and strong. I hooked stump with it the other day and just about pulled myself into a hole. There are diesel shops in town, but I don't really trust anyone to work on my stuff. The nearest Tak/Yanmar dealer is in Portland, OR. A bit over an hour away.
I found the service manual for the engine, but apparently governor adjustments are verboten to non factory service personnel.
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Post by spud on Dec 7, 2019 18:59:23 GMT -8
s3.amazonaws.com ... pretty complete info yanmar manual. Pretty much zip on the yanmar pump. Lots of info otherwise. Point is if your pump is suspect you cant do a lot with it. Gotta rule out everything else forst. Fuel supply quality quantity pressure air content. Smoke analysis in troubleshooting guide suggests some things to check . Fuel type assumably is low sulfur automotive diesel. Not that off road red fuel will give a mild increase in power, if the fuel system is ok to use it. Assume you got this unit used, valve lash should be verified. If power level is suspect after fuel supply is proven sound, you are at the jumping off point, because the pump may be suspect. Lookin at specifications, that engine is rated at various output from approx13 kw at 1500 to 27 kw at 3000 rpm. Suggesting a simple higher rpm may cover your power. No smoke is a good thing as far as engine condition. But does suggest low fuel delivery. Quick fix? Most expensive option. Try another pump. Careful timing is required. Notice how to time the yanmar pump. Quite convenient actually. Easy to screw up too. Have your pump mounting screws been tampered with... clean smoke suggests good pump timing. Too much advance will lose power, too little will lose power and begin white smoke...
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Post by 69Rebel on Dec 7, 2019 19:20:06 GMT -8
There are no marks on any of the bolts or fuel hard lines. Used, yes. These machines are about $60K+ new.
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Post by spud on Dec 7, 2019 19:50:09 GMT -8
Oh i am aware of the costs of equipment trust me. My idea is that sometimes machines get sold traded and auctioned due to problems that people dont wanna fix. And i can assure you many many times expensive equipment gets very poor maintenance and even abuse. Sounds like your problem has a bright side. That engine should last longer . Horsepower/ hours. IF... your low on power, you WILL get more hours out of it. If you work it at HI power, you WILL be overhauling it sooner.
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Post by 69Rebel on Dec 7, 2019 20:02:16 GMT -8
Those Yanmar engines run forever. My old machine had well over 10K hours on it, and it still ran great. Puffed a little blue smoke on cold start up, but didn't use any appreciable amount of oil between changes.
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Post by 69Rebel on Jan 11, 2020 15:05:17 GMT -8
I just ordered up a "pop" injector tester. As soon as it gets here from China, we'll take a look at how the injectors are doing and report back.
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Post by spud on Jan 12, 2020 7:55:14 GMT -8
My thoughts there is they aint injectors, they are called nozzles. How they work is like they hold back the fuel till the pressure rises to the point where they open ( injection pressure) and then the fuel sprays out at high pressure and atomizes. Usually from four or six tiny holes in the tip. Nozzle problems usually manifest as poor atomization which results in smoke and less power. If the nozzles are weak and they open early you get the same effect. If you have some plugged orifices you can get lower power, but the fuel can also find its way out the other orifices and maybe not cause a noticable loss. If the orifices are enlarged( they do this over time) you get poor atomization and smoke, but an increase in power is generally found( once new nozzles are put in the operator always reports a power loss over nicely worn nozzles since they overfuel) So in most cases nozzle problems give smoke, and not a power loss. If you really have low power in that type of fuel system it is more likely low delivery from pump, in general terms, due to various things. Have you tried increasing throttle travel ...
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Post by 69Rebel on Jan 12, 2020 9:40:14 GMT -8
When I got it, it wasn't going to full throttle. There was space between the arm and the stop, so I adjusted the throttle cable. I gained some RPM, but that was all. Around here, it's like everybody who ever knew how to work on an all mechanical diesel went off and died. All anyone knows is electronic common rail systems. "Bring it down, we'll hook it to the confuser and scan it." If they can't hook it to a computer, they're as lost as I am. But I'm not a mechanic by trade.
There is a possibility that I missed a restriction in the fuel system, I'll be double checking my work there, too. It wouldn't be the first time that I overlooked something stupid.
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Post by 69Rebel on May 13, 2020 11:23:41 GMT -8
Problem solved!!
It was the hydraulic pump. This unit uses a variable displacement axial piston pump with two self equalizing pressure outlets, along with two fixed displacement gear pumps stacked on one end. After much wasted time, trying to find someone to work on this seemingly super complicated Japanese pump, and getting lots of runaround to the effect of "it's probably cheaper to buy a new one", and " I don't know how to even hook this up to the test fixture" I just threw it on the bench and tore it down myself. It looked totally pristine inside, maybe a little wear on the piston shoes, but other wise primo. It looked so good that I really didn't scrutinize it all that closely, but apparently I either unstuck something, or dislodged some shit that was blocking a port. I slapped it back together, put it back on the machine, bled the system, pressurized the system (completely sealed hydraulic system, that is under some pressure at all times), and the friggin' thing runs and operates beautifully. All I can figure is that the swash plate wasn't deflecting enough with changing load conditions and was trying to deliver max flow at all times. Or, maybe something just fixed itself.
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