Pulled the motor this morning and this is what I f

[Anonymous Poster]

I pulled the moror out of my early 80's B 7100 this morning after getting a severe oil leak yesterday morning shortly after start-up and found that a little plug blew out of the timing cover on the bottom of the cover in an oil passage. Just as a precaution, I also pulled the flywheel off and found that the rear main seal blew out of the back of the block also... Anyone had this problem before and what did you do about the plug in the timing cover if so? The rear main is no problem and I will check and clean the oil pressure relief before reassembling but the plug in the cover looks like it may be a problem cause I don't believe it was every supposed to come out even if you wanted it to... Any ideas anyone... Suggestions?... Thanks in advance... Visa...

 

[hayden]

You're right to search more closely for the real source of the problem. Rear oil seals and oil galley plugs don't just pop out for no reason. You must have built up some major oil pressure to do that.

You might want to replace the relief valve as a precaution. Have the oil and filter been changed regularly? You might have an obstruction somewhere.

I'd put a pressure gauge on and at least crank the engine to see what pressure you get. Preferably, you might find a way to run the engine before putting everything back together, but that might be difficult. IF you still have a problem the gauge should show it.

Another thing you could try is fitting an air line to the oil system, and see if it passes air or if pressure builds up. You will of course have to plug up the oil pump inlet somehow.

When you reassemble the machine, definately use a gauge when you start it up. If the pressure jumps too high you can kill the engine, hopefully before blowing everything out again.

Hopefully you will find a clear source of the problem

 

[heehaw]

just curious how its going with your repairs??
heehaw

 

[Anonymous Poster]

All is well with the repair. Finished it and fired it about midnight last night. All leaks seem to be fixed. Only hang up was the plug that blew out of the cover. Nobody had any idea where to get on from so I had to drill and tap the hole to 1/4pipe and install a pipe plug. All in all , it was about a $80.00 repair and took about 7 hours start to finish. Thanks to all who replied... Visa

 

[Kelvin]

I've not been on in a while so I've missed part of this post...

I'll add some belated information.

I believe that overheated engines are to be expected on a lot of the 70s and 80s compact Kubotas based upon owner/operator's unfamiliarity with the thermo-siphon cooling systems. I will emphasize that the system is a good cooling system, just different from what most Americans are used to. That is what happened to my B7100. After an apparent overheat from the previous owner I had two of the three compression rings go bad. This caused excessive blow-by and oil leakage out of the valve cover vent tube that progressed from heavy smoke to oil literally pouring out of the tube and onto the ground. This is obviously due to high pressure bypassing the pistons and getting into the bottom of the engine. In my case the pressure went up through the oil passage ways into and out of the valve cover.

It is possible that you may have bad compression rings as well. If so, your problem will return. If you are not familiar with thermo-siphon cooling systems, then you need to be. There are lots of posts here about that.

Again, sorry about the belated post. I sincerely hope that your problem was not compression rings like mine.
Kelvin

 

[Anonymous Poster]

Back in 1975 I was the proud owner of a new B6000 tractor. One the third day of ownership, I started the engine and the oil pressure light did not go out. I shut it off and called the dealer. He picked it up that day and I followed it back to the dealership. They pulled the oil pan and found an oil galley drilling plug laying in the oil pan. As I remember, the plug was aluminum. They fattened it a bit with a light hammer tap, tapped it back in the hole, and peened it in place. Haven't had another problem in 25 years of ownership. Obviously, my plug was poorly installed and failed early. Yours probably was marginal and it just took a little longer. In my case the higher pressure at start due to cold oil probably helped. Had it failed while operating the tractor, I would probably not have noticed the light and the engine would have been history.