Oil pressure woes

[Sterno]

My little B6100 is having a bit of a fit, the low oil pressure light starts to flicker on when the tractor warms up. If I bring the rpm up a bit the light goes out, new oil and filter and no change so here's the question:

What are the odds of it being a sticking pressure relief valve?
Is it more likely to be a worn oil pump and main/rod bearing clearances, I'm trying to decide if I should tackle the job myself or take it in to the shop.

I have the service manual and am experienced in doing engine rebuilds, just not diesels.
Thanks

p.s. Tractor has 746 hours on it.

 

[dmanlyr]

Welcome to the orange!

First thing I would do is verify the actual oil pressure with a known good mechanical gauge.

Then I would verify the proper engine idle rpm and that it is to spec, and not that some well meaning, but ignorant person has not turned it down because they though it was idling too "fast"

Next, although I am assuming this to be the case as I have not metioned it earlier, verify that the proper Kubota oil filter (aftermarket filters may or more likely, NOT be equal to the oem filters) and recommended weight of lube oil is being used.

Please report back your findings.

David

 

[Bulldog]

Welcome to the orange!

First thing I would do is verify the actual oil pressure with a known good mechanical gauge.

Then I would verify the proper engine idle rpm and that it is to spec, and not that some well meaning, but ignorant person has not turned it down because they though it was idling too "fast"

Next, although I am assuming this to be the case as I have not metioned it earlier, verify that the proper Kubota oil filter (aftermarket filters may or more likely, NOT be equal to the oem filters) and recommended weight of lube oil is being used.

Please report back your findings.David

I second that... All very important points that you need to know for certain before taking it out of service.

746 hrs is nothing. My old 7100 had over 6000 hrs on it when I traded it in on a new Kubota. Nothing had ever been done to the engine but regular service.

 

[vtmbz]

Although i am not an expert by any means, I've noticed that diesel engineeris spend a lot of time containing vibrations: meaning that over time a lot of things get loose, fall out and rattle. A defective ground would give you some of these symptoms.

I just rewired my b5100 and found the oil sensor was leaking oil and obviously defective. The PO had removed the idiot light and replaced it with nothing. I put in a new gauge and sensor.

I use a lot of locktite blue when working on my tractor.

 

[Big Kahuna]

Hey. you have a very easy fix here, the sending unit is bad, been down this road before, replace it and you'll be good to go.

Part Number

15841-39010 $18.13 in stock at Messicks.


Big Kahuna

 

[Sterno]

Thanks for the quick reply. Yes it is an OEM Kubota oil filter and 10W30 oil as recommended.
The tractor's at my parents house one hour away, so I can't work on it daily but will keep you guys updated.

I'm assuming the oil pressure sending unit uses a standard 1/8" npt pipe thread? Also, as I'm new to diesels, what can I use to check RPM, apart from buying one of these: http://tinytach.com/diesel.php (saw it around the forums)
I want to try and have everything I need organized for my next rip down there.

 

[ipz2222]

Your eng may be one of those that had the cam (oil) plug that would blow out. Use the search block at the top of the page , "low oil pressure L235" , There are pictures in that thread.

 

[Sterno]

So it looks like I'll be tearing the engine apart, kinda how my luck goes.
I checked Idle RPM, 760 warmed up.
Plumbed in a mechanical gauge, 15 psi at idle cold and 20psi at 2000 RPM, hot its 6-7 psi at idle and 11 at 2K RPM.

Tractor is parked until i get this fixed, hopefully the bearings aren't trashed!

 

[kubotasam]

Your eng may be one of those that had the cam (oil) plug that would blow out. Use the search block at the top of the page , "low oil pressure L235" , There are pictures in that thread.

Check into IPZ's advice about the cam plug. I does happen to some Kubota tractors.

 

[Sterno]

So I finally have a bit of time to tackle this project, am going to try to fish my inspection camera through the access cover for the governor springs and have a look, has anyone tried this, is there enough room? (9mm camera head)

I looked at the online parts manual and see that it calls out 2 cam plugs in the parts list. The parts diagram doesn't show the 2nd plug which leaves me wondering.
Is there a plug at the rear of the cam, and is it accessible through the expansion plug or does the cam have to come out? the diagram of the L235 does show plugs at either end so i'm assuming mine's similar.

 

[Countrymech]

So I finally have a bit of time to tackle this project, am going to try to fish my inspection camera through the access cover for the governor springs and have a look, has anyone tried this, is there enough room? (9mm camera head)

I looked at the online parts manual and see that it calls out 2 cam plugs in the parts list. The parts diagram doesn't show the 2nd plug which leaves me wondering.
Is there a plug at the rear of the cam, and is it accessible through the expansion plug or does the cam have to come out? the diagram of the L235 does show plugs at either end so i'm assuming mine's similar.

I admit I'm guessing here, but I'd figure that a blown cam plug on the back of the engine would cause a bunch of oil in the bellhousing/transmission case as applicable. If that were the case, it might color the transmission oil black.

 

[ipz2222]

The blown cam plug is in the front of the eng. I was going to mark the front cover of mine where the centerline of the cam was while I had it off ,, but didn't. countrymech, did you find the pictures in the thread I had taken.?? Maybe it will give you an idea where to look.

 

[Sterno]

Thanks IPZ, I'm pretty confident I'll find it, just other stuff got in the way today (again!)
The service article by ServiceDeptVic regarding oil in your coolant shows the removed gearcase nicely btw. http://www.orangetractortalks.com/2008/12/found-oil-in-your-coolant/

 

[Apogee]

I believe that sending unit has metric threads. It would be best to get it from Kubota so the turn off pressure is correct for the application.

I'd also check the cam plug at the front of the engine. However, I'd only do after changing out the pressure sending unit. Their failure is a known problem.

Finally, are you using a Kubota oil filter? I've read where folks have had problems with running other filters as the relief pressures are different. I definitely have had this problem with my Range Rover. I know, it doesn't make sense, but it fixed a flashing oil light issue on my Rover and I've read something similar on Kubota's before.

Good luck!

Steve

 

[Big Kahuna]

I think you're itching to tear down an engine that don't need it, do you really believe that it took 30+ years for that cam plug to fall out? I've heard this story of cam plugs for years, I know of only 1 tractor that had this happen to. Slow down... you checked oil pressure as noted, what psi gauge did you use? 60 is what works the best. Are you using oil or synthetic oil? is this worry all over the light or is there more to this story? The tractor runs okay? Right? Change the sending unit then update this thread.

Big Kahuna

 

[Sterno]

I did order a new pressure switch (it's cheap enough and easy to swap) along with the rest of what I'll need but my extremely low oil pressure, using a quality mechanical gauge known to be accurate (yep 0-60 psi), tells me I've got bigger problems than a failing switch..

 

[z751-hy]

I am having same problem w 2cyl Diesel. Down to 5psi at 700rpm, and 11psi at 2700rpm, good gage. New oil/filter, same. Old oil was not that gross, I only changed it because I did not know how old it was, and I had such low psi. It looks like the easiest thing to check is the sump intake. I hope its clogged. It seems logical in your case. My Z751-HY engine seems to perform well, and sound good and smooth, but this is my first diesel, so I don't think I am a good judge.
I will be following this, and will contribute if I have anything worthy.

BTW, the sender hole was metric. I retapped mine to 1/8-NPT so I could use cheaper (free) parts. So, I got a gage and sendingSW on a brassT. Its a bigger hole, so the metric sender will fit, but might leak at normal psi, or might strip threads. In other words, I can't go back, but I can't see why I would.

 

[eserv]

I did order a new pressure switch (it's cheap enough and easy to swap) along with the rest of what I'll need but my extremely low oil pressure, using a quality mechanical gauge known to be accurate (yep 0-60 psi), tells me I've got bigger problems than a failing switch..

Your B6100 will run for years with 6 or 7 psi oil pressure at idle when hot!. New bearings and a new oil pump will make it like new again though if you really can't live with that light at idle! ( put a guage on it instead of the light! 6 psi on a guage is easier on the eyes than a flickering red light!) LOL!
Ed

 

[z751-hy]

You mean low oil pressure is ok?

I came back to post to change the eMail setting so I get notified (new), and I see your post about 6-7psi at idle is ok. Would you expound upon that?

Thanks

 

[z751-hy]

test. I am posting to see if I get an eMail