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Kubota B7100 oil pressure

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md20201
Join Date: Oct 2007
Posts: 3 north carolina
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2007-10-25          147367

b 7100 oil pressure light comes on at idle, installed gauge only getting 6-15 psi. changed oil has 700 hrs, runs and sounds great anyone had this or can help me?

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Kubota B7100 oil pressure

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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2007-10-26          147382

Md20201,

Low oil pressure is usually caused by wear, which takes place between the crankshaft bearings and rod bearings.

As the gaps between the bearing surfaces widen, due to engine wear, the engine oil will begin to flow more easily between the surfaces. This means that less oil is going to the moving parts......and more oil simply dripping back into the oil pan. As the gaps between these surfaces widen, the oil pressure begins to drop off.

Should this condition get much worse, you'll eventually lose all oil pressure to the rod furthest from the oil pump. YOU DO NOT WANT THIS TO HAPPEN. If this happens, you could spin a bearing, break a rod, or even break the crankshaft. Any of these things could destroy the engine block, making it impossible to overhaul.

Each time the engine is started, it takes a few seconds before the oil reaches the moving parts. It is during these first few seconds that the majority of all engine wear takes place. The condition worsens during extremely cold weather, due to the fact that the oil doesn't begin to flow near as soon at it would when warm. At temperatures below -30 degrees F., starting a cold engine could destroy it.

I don't want to alarm you, but it sounds to me as though you are in need of an engine overhaul. Your overhaul will not be too expensive, provided you have it done rather soon. It's highly likely that you'll only need new crankshaft bearings, rod bearings, and piston rings.

Joel
....

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Kubota B7100 oil pressure

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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2007-10-26          147383

Md20201,

Maybe I misunderstood you. It might be best to back up a bit here.

When you wrote, "installed gauge", did you mean to say that you tested the oil pressure with a test gauge? If not that, then maybe you were referring to the installed dash gauge?

If you haven't yet tested the oil pressure with a certified test gauge, please do that first. If you are getting proper oil pressure readings on the test gauge, it is then more likely that you either have a faulty oil pressure sensor, or a faulty dash panel gauge.

Fill me in. Thank you.

Joel ....

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Kubota B7100 oil pressure

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md20201
Join Date: Oct 2007
Posts: 3 north carolina
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2007-10-26          147387

replaced sensor, light still on at idle Believe it are not the Kubota dealer told me my oil pressure should be 7psi I contacted kubota and they said 28-64psi makes more sense, added a gauge to test the pressure, best I got with open throttle 15-18 idle 5-7. this has gone on I hate to say a couple months and have used the tractor.
It started all at once. tractor only has 700 hrs I changed the oil,Hard to believe this tractor is worn out last owner as far as I know mainly mowed with it. The oil in all the ares of the tractor looked as if it had never been changed. Do you know if the engine has to be pulled to remove oil pan or timing cover? Thanks ....

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Art White
Join Date: Jan 2000
Posts: 6898 Waterville New York
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2007-10-26          147391


If it was mine, you are at your minumums but it doesn't mean anything has been hurt yet. I would try changing the oil out with a few short hours maybe five of running, filter would not need to be changed but advisable. The relief valve might be the only problem as you are low on oil pressure. Keep in mind diesels make oil dirty quickly! ....

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Kubota B7100 oil pressure

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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2007-10-26          147392

Md20201,

Diesel engine oil always looks black as coal. It's the nature of the beast. It would be very difficult to tell if the oil had been changed on a regular basis, just by looking at the oil. Fresh oil will turn black after just a few hours.

I highly doubt that you have a bad oil pump. Oil pumps either work, or they don't. I've never seen an oil pump get weak.

Did you change the oil filter when you changed the oil? Is it possible that you installed the incorrect filter, or that the filter was faulty? I'd change it again, just to make sure we can eliminate a plugged or faulty filter before going any further.

Aside from this, your only recourse is to get yourself an engine repair manual, from Kubota. After checking to make sure the problem is internal in nature, I'd pull the engine as soon as possible, before any catastrophic failures occur.

Engine life isn't so much dependent on what the tractor was used for, as it is the number of times it was started.

I really wish these little tractors had a meter which records the number of starts, in addition to the number of operating hours. It's the number of starts that takes its toll on any engine. Compact tractors are abused in this regard. Far too many people will start their tractors several times each day, and never run the things for more than five minutes at a crack. This continued abuse will kill a diesel engine.

Please don't allow your engine to destroy itself. Your engine can be saved, so long as you take the necessary action to get it repaired right away. If you would feel better about it, take it to an authorized dealer and have it inspected. The extra cost to have a certified mechanic diagnose your troubles could prove to be a worthwhile investment.

I wish you all the best, and I'm very sorry to hear the bad news.

Joel ....

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Kubota B7100 oil pressure

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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2007-10-26          147395

Art White,

I completely forgot to mention the relief valve! It really could be that simple.

Many thanks.

Joel ....

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Kubota B7100 oil pressure

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randywatson
Join Date: Apr 2007
Posts: 109 texas
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2007-10-26          147405

Oh boy, what year is the 7100, on some of the early models there is a rubber plug in the end of the cam shaft, it came out causing low pressure.

Lots of them have been repaired early on.

I'd definately start with a test gage on the system and make sure of the reading. Correct should definately be more than 7 psi.

are you using and have the correct filter and weight oil
just because it was used for mowing and only has 700 hrs does not mean the oil and filter are correct,

a cheap filter and wrong oil can cause low pressure

There is also the issue of the bypass valve, usually dont go bad, they allow oil flow to bypass filter if it becomes clogged and pressure gets to high.

You have to take the front axle off to take off oil pan and timing cover.

....

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Kubota B7100 oil pressure

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md20201
Join Date: Oct 2007
Posts: 3 north carolina
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2007-10-27          147438

Pressure fixed cam shaft plug missing. 55psi now thanks all ....

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Kubota B7100 oil pressure

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candoarms
Join Date: Mar 2007
Posts: 1932 North Dakota
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2007-10-27          147442

Md20201,

I'm very happy to hear the good news. I learned something new today. I'm assuming that Kubota no longer has this plug in their camshafts.

RandyWatson,

Many thanks for the lesson. It's people like you who convinced me to become a member of this fine group. What a treasure this place is, thanks to the people, like you, who make their experiences available to all. :)

Joel

....

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Kubota B7100 oil pressure

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randywatson
Join Date: Apr 2007
Posts: 109 texas
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2007-10-29          147496

yeah, they resolved the cam shaft plug several years ago, but there are still a few older tractors out there which have never been repaired,

anywho, glad it's fixed. ....

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