How to fix an oil leak?

[cnr6400]

A cork approach would be a practical fix rather than tearing down the front plate and sealing the gasket.   To reduce the oil volume the hole could hold, you could make a steel or aluminum or brass rod to mostly fill the hole, with an o-ring at the outer end. An internal thread at the end could be added to make it easy to extract the rod if you ever need to. Just food for thought.

(This is after all a tool, it does not have to be perfectly oil tight. Many lathes like my old worn out South Bend 9" are manually oiled at every use and seep a bit into the trays at every use. I have adapted baking sheets and tins as trays to catch most of it. The gear oil on the change gears gets reapplied now and then from its' tray with a syringe.)

[Kim]

I like that idea - using a rod to fill the hole.

And re-using the oil that leaks out is a pretty good idea too!

Thanks Jeff!
Kim

[cnr6400]

My pleasure Kim! By the way I did mark the lathe's baking trays with skull and crossbones in case someone in the house needed an extra tray for cookies and was tempted to lift the shop ones. Oatmeal raisin with high sulphur gear oil flavour cookies would not make fer a good coffee break!   

[Kim]

But the Elves might like them? 

Kim

[Kim]

Oil Leak check, Day 3:
No signs of leaking…


Oil Leak check, Day 5:
Still no signs of a leak!
I’m optimistic that my little tightening exercise may have worked!


Oil Leak check, Day 9:
Definitely still leaking


It couldn’t be that easy anyway. What was I ever thinking? 

Looks like the same hole as I saw before.

The paper towels were clearly soaking up oil. But due to the wicking, I couldn’t tell exactly where the leak was coming from, other than in the general area around the sight glass.   There was oil on the underneath side of the gearbox that I could feel, but of course, I couldn’t tell if it was dribbling down the front and going underneath, or if it was leaking underneath and the buildup in the hole was just a side effect.

I decided to try and plug the hole and see if that helped.  If it keeps leaking, it's probably coming from the seal between the gearbox cover and the gearbox itself.   If the plug fixes it, then containing it in the hole should suffice.

So, I set about making a plug.  I looked for a cork, but couldn’t find one.  Then I thought about making some elaborate screw-in plug with an o-ring but that seemed like a LOT of work for something I’m not even sure will help.

In the end, I found a wooden dowel that I turned down to size to fit the hole.  My original thinking was to make a tapered plug to fit the hole and push it in place. And I wanted to make the plug deep and to mostly fill the hole to decrease the dead space that had to be filled (as we talked about before).

But when I was test-fitting the plug in the hole to make sure it would fit, I found out that the diameter decreases just a smidge about 3/4" into the hole.  So the hole behind the cover is just a little smaller than the hole in the cover itself. And the size I had turned, accidentally, was a nice tight push fit for that slightly smaller size.  So, rather than look a gift accident in the mouth, I chose to embrace the accident and leave the cork as is and see if plugging the hole at the deeper location would help.  If it does, then I’m good.  If it doesn’t, then it’s probably the seal between the cover and gearbox that’s leaking (right where the hole gets slightly smaller.

Here's the plug I made:



So that’s my plan.  I cleaned it up and I’m going to wait a few more days and see what happens!

And here it is in place:


Until the next installment of "As the Oil Churns"...
Kim

[cnr6400]

"tune in to next week's episode to see if the rich lady doctor marries the lube technician."

[crueby]

The plug seems like a good way to determine if thats where its coming out into the tray. But, if it is, that just means there is something else farther up the line in there that is leaking, right? Damming it there could cause something else to empty out and form a hidden lake? I don't have a good feel for how that machine is put together so I may well be misunderstanding it, I just don't want you to hide a problem and make it worse if another part doesn't get the oil it needs.

[Kim]

Thanks Chris,

Well, the oil in the quick change gearbox is supposed to stay in there.  It only provides splash lubrication to the gears in the lead screw change gears (which are all in that box).  If the oil goes anywhere else, then that's the problem

So if damming it up keeps it from leaking out, I'm good with that.  If it runs somewhere else in the machine, that's less ideal, but I can't see that it will hurt anything other than possibly making an oil puddle somewhere else.  And I'll know that, even if I can't see the puddle, because the oil level in the gearbox will go down.

This is my current thinking at least.  I'm fully willing to change my think if required!   

Kim

[Don1966]

Looking at the diagram the hole your plugging is acting like a weep hole to give you and indication that your seal is leaking. Weep hole are used in equipment where you can’t see what’s happening inside. I may be wrong but I have seen them in equipment for that purpose.

Regards Don

[Kim]

That's interesting Don!  I've never heard of a weep hole. That could be what this is.

I do think that it is also, an access hole for the SHCS that hold the change box to the head of the lathe.  If you look at the diagram (which I'm reposting here) you can see item 391 is a long cap screw.  It just shows one of those screws, but there are really four of them. One in each corner of the change box.  (Look along the bottom of the change box to the left of the green arrow to find #391.)


Anyway, I hope that my plug will stop it from leaking.  If not, I'll have to take more drastic steps. Or alternately, continue to ignore it. 

Kim

[larry_g]

I'm a bit late to the party but one thing that I use to find leaks is toilet paper.  Whether water or oil the TP will immediately turn color when it is wet.  Great for finding small leaks.

lg
no neat sig line

[crueby]

Looking at that diagram, boy there sure are a lot of parts there!  I take it that undoing the front cover bolts to remove plate 450 and put it back on again would be a major pain in the end mill, to get all those shafts lined up and back on again? Could well be that gasket 396 is seaping at the corner there at the red arrow, dripping into that hole you plugged. If so, the plug is probably a good fix.

[Kim]

Looking at that diagram, boy there sure are a lot of parts there!  I take it that undoing the front cover bolts to remove plate 450 and put it back on again would be a major pain in the end mill, to get all those shafts lined up and back on again? Could well be that gasket 396 is seaping at the corner there at the red arrow, dripping into that hole you plugged. If so, the plug is probably a good fix.

Yeah, that's kind of my hope right now.  I do think pulling that whole thing apart will be a major project.  And then getting it back together so that it works, and DOESN'T leak anywhere else would be a real challenge, I think.

Anyway, I'm pulling for the more makeshift kind of fix - like the plug

Kim