# Kubota blowing oil



## knucklebuster (Jul 12, 2007)

I'm hoping someone on here has experience with Kubota diesel engines.
I bought an older Kubota b5100 2-wheel drive tractor. The guy I bought it from said the 2-cylinder engine was locked-up. It actually rotated 1/2 turn in either direction and then stopped. I figured a rod left go and was jammed against the block. I dropped the pan and found nothing wrong. I pulled the valve cover, rockers, and head, also finding nothing wrong. I was starting to feel defeated when I decided to try to turn the motor over again. It turned over fine now. Nothing stopping it.?????
So I put it back together with new gaskets, oil, and fuel. Bled the air from the fuel lines and tried to start it up. Engine cranked fine. Even had black smoke coming out the exhaust. Then I noticed all my new oil was squirting out a round hole on the side of the block, between the oil filter and the starter. There's actually 2 holes, about 3 inches apart. The bottom hole isn't open. The top one is and that's where the oil is coming from. The hole isn't threaded. Whatever was in there looks as though it gets put in from the outside because it has a shoulder maybe 3/8" in from the end.
What is this hole for and why is oil squirting out when I crank the engine over?
Does this have anything to do with the engine locking up prior to me doing any work to it?
I'm experienced with other small engines, but not Kubota diesels.
I'm confused. Can someone help?


----------



## paulr44 (Oct 14, 2008)

A half-turn in either direction is truly a quandry being we're here in digital-land, and you're there.

As for the oil coming out of the hole, given it's proximity to the oil filter I would think it's probably for an oil sending unit. So, is there a wire hanging down in that area that's not connected to anything, perhaps someone taped the end up and "hid" it amonst others? It could be there's only supposed to be a plug in it, but without more unit and engine info. I can't help you here. Need to at least post all engine numbers, and if possible unit numbers. You state there aren't any threads in it...perhaps the threads have been pulled out (stripped)?


----------



## knucklebuster (Jul 12, 2007)

paulr44 said:


> A half-turn in either direction is truly a quandry being we're here in digital-land, and you're there.
> 
> As for the oil coming out of the hole, given it's proximity to the oil filter I would think it's probably for an oil sending unit. So, is there a wire hanging down in that area that's not connected to anything, perhaps someone taped the end up and "hid" it amonst others? It could be there's only supposed to be a plug in it, but without more unit and engine info. I can't help you here. Need to at least post all engine numbers, and if possible unit numbers. You state there aren't any threads in it...perhaps the threads have been pulled out (stripped)?


There was only one engine available for the B5100e.
It's the Z500-1A
Twin cylinder liquid cooled diesel.

I checked all the basic stuff like you mentioned. No threads in the hole, now or ever. No loose wires. I doubt only a plug goes in there because it would "blow" out under pressure, as my new oil did.
If I could find a parts break-down sheet showing the engine and all it's parts, I probably could figure it out. 
I've been working on small engines for the past 35 years, but these little diesels are new to me.


----------



## usmcgrunt (Sep 16, 2007)

Hello knucklebuster. Here is a link to a parts manual that "may" help figure out what part is missing. Select model B5100e.I hope this helps.

http://kubotabooks.com/AutoIndex/index.php?dir=Tractor Parts Manuals/

And this for owners manuals-

http://kubotabooks.com/AutoIndex/index.php?dir=Tractor Owners Manuals/


----------



## knucklebuster (Jul 12, 2007)

usmcgrunt said:


> Hello knucklebuster. Here is a link to a parts manual that "may" help figure out what part is missing. Select model B5100e.I hope this helps.
> 
> http://kubotabooks.com/AutoIndex/index.php?dir=Tractor Parts Manuals/
> 
> ...


Thanks. I really appreciate the PDF's.
That's what I was looking for. I found the holes in question, unfortunately, it doesn't show anything in either of pdf's. 

Here's a picture of the holes. (click the picture)

The bottom hole is closed off and is fine.
The top hole is open and it's where the oil is pushing out.


----------



## usmcgrunt (Sep 16, 2007)

I also could not find the missing item on the parts list. I DO agree with paulr44 that it could possibly be a missing welch plug since the hole is counter bored for a reason. A correctly installed welch plug should not leak under the small amount of pressure from the oil pump.


----------



## knucklebuster (Jul 12, 2007)

Yea, i'm starting to agree with the plug theory. 
What can I use to plug it since there doesn't seem to be a replacement plug available?
I have a small diameter copper rod I can hack a piece off of. It's soft so it should drive in fairly snug. Clear nail polish should seal it ok.
What would you use?


----------



## paulr44 (Oct 14, 2008)

If no threads, not now not ever, then welch plug as the GI-rene suggests would be my thoughts too. Clear nail polish is what we use on carb. welch plugs as it's impervious to fuel, it isn't something I'd trust with oil pressure. A tolerance fit should be all you need, so a chunk of brass rod ground with a slight taper should do the trick.


----------



## knucklebuster (Jul 12, 2007)

I fixed it. Just took a small piece of the copper rod I had laying around and ground it slightly around the perimeter, until I got a tight fit. I didn't taper it because I didn't want to take the chance of it acting like a wedge and cracking my block. After I slid it in the hole I used a center punch to spread it out and tighten it up. Topped it off with nail polish. 
Nail polish should be fine for all petroleum products.

Thanks paulr44 and usmcgrunt for your help.


----------

