Sudden Oil Leak in back of Engine B7100

[JerryC999]

After a couple of years of perfect cleanliness, my B7100 HST has suddenly started leaking oil at a high rate off of the rear left side, mostly while running and hot. It can go through a pint in 3 hours while running. It seems to be below the head gaskets, and shows up in multiple drips off the oil pan and onto the belly mower.

Next steps? I can keep adding oil to get to winter time, but what are the potential culprits? Minor, I hope?

 

[North Idaho Wolfman]

There is a plug on the back of the block, directly across from the oil sender.

 

[JerryC999]

There is a plug on the back of the block, directly across from the oil sender.

That would be if that is all it is. But how easy to get to that? Have to pull the engine or can I get to it from below? Not much room back there.

 

[tbk5]

Check the oil sending unit too. I once pulled an auto engine to change a rear main seal that looked to be leaking. After putting everything back together, I still had a leak. I had cleaned all the grime away before reassembly and sure enough, the sending unit leaked under pressure.

 

[N3BP]

Those pins are a pain in the rear. Both of mine leaked on my B7100 too. I first tried to hammer them back in to reseal them but that didn't work. I then got replacements (they still make them) and drilled the old ones out. After hammering the new ones in I also put RTV around them just as an added measure. Hasn't leaked so far.

 

[JerryC999]

Check the oil sending unit too. I once pulled an auto engine to change a rear main seal that looked to be leaking. After putting everything back together, I still had a leak. I had cleaned all the grime away before reassembly and sure enough, the sending unit leaked under pressure.

That would be great, but in the picture, doesn't it look like it is below the sending unit? I did crank a little on it, but do not want to break it. I could just replace it anyway, though.

 

[North Idaho Wolfman]

If I remember correctly you can pull the shutter plate off and the fuel tank and get to the plug.

 

[tbk5]

That would be great, but in the picture, doesn't it look like it is below the sending unit? I did crank a little on it, but do not want to break it. I could just replace it anyway, though.

Yeah, I think I get a mental freeze when i think about rear of engine oil leaks. My dad and i actually pulled the engine twice one weekend to change the rear main seal on my car. With the engine running, you could se the oil stream down between the engine and transmission bell housing. The first time, we changed just the seal, we had a "I know what I am doing" argument. We had lots of old vs new way of doing things arguments over the years. This argument, err, lecture, was about not needing to change the aluminum housing that held the seal. After all, it cost as much as the seal! :grin: (My point was that $10 was good insurance against the potential of a warped aluminum seal bracket.) Anyway, we still had a major leak after assembly. So we pulled the engine out again. While dad went to buy another seal AND the housing, i degreased and cleaned up the engine. After reassembly 2, it still leaked. We were both wrong. But, this time, with a clean engine, i was able to trace a leak to the sender which was not in plain view. The oil driped into the timing window of the bell housing and out the bottom. Doh!

The plug mentioned above may be a likely cause. I am not familiar with it. It may be worth cleaning/degreasing the area before taking things apart to help spot the source of the leak.

 

[N3BP]

http://www.orangetractortalks.com/forums/showthread.php?t=27620

A picture showing what my oil leak looked like. Caused by those pins.

 

[JerryC999]

Thanks, all. Yep, no way around just clearing out the clutter, cleaning the engine, and taking a good look around before I do anything else. I will report back on what I find. You all have listed several possible culprits, and no sense pulling the engine twice!

I could just keep adding oil and cleaning up floors, but I sure do like clean engines. All that oil just bugs me.

 

[JerryC999]

News is that it is the head gasket, leaking right off that back left corner above the oil sending unit. Could be worse, indeed.

 

[D2Cat]

Jerry, when you remove the head you'll find an "0" ring back there. See this picture bottom right corner with the tube protruding up a bit. It goes around it, and your is probably the culprit.

 

[JerryC999]

Thanks for the heads up. Does that O ring come with the head gasket, or do I need to make sure I also get it separately? I will talk with the Kubota guys today about getting what I need.

 

[D2Cat]

I'm pretty sure if you get your parts from Kubota the O-ring will be a separate item. Some aftermarket sellers include it. But, either way, ask the parts guy for it. Good luck

 

[JerryC999]

I'm pretty sure if you get your parts from Kubota the O-ring will be a separate item. Some aftermarket sellers include it. But, either way, ask the parts guy for it. Good luck

Just to report back: That leak was indeed from the back, left corner of the head, right where that O ring was. . .not. Someone had used some kind of silicone or something previously to stop a leak, and so I was the lucky inheritor of a poor repair job. However, with a new head gasket, O ring and oil sending unit, she is back to dry as a bone and running fine.

Thanks all for your help.

 

[D2Cat]

Good to hear Jerry. It's nice you report back so in the future others might find the thread and learn from it.

It amazes me how someone would remove all the parts necessary to get to a head gasket and then not spend a couple of dollars to get the correct 0-ring in there. Leaving the high likely hood it will all need to be done again real soon!

Merry Christmas!!