Round Dial gearbox oil leak

I looked for gearbox oil leak threads and found quite a few for square dial machines but none for round dial machines. Maybe there are some in larger rebuild threads, would appreciate any links to such if they might help.

The 1940 machine has a slow leak from the gearbox. There is evidence of the leak both in the motor compartment and from the weep hole below the bed. Here is a picture that shows the leak. Under the drain pipe is a layer of oil. This is not a recent leak, I have had it since I bought the lathe in the 1990's.



I tried to solve this by removing and reinstalling the drain pipe two or three times, but no luck. As the photo shows, the sight glass is below all other openings to the gearbox, at least in the front, other than the drain pipe. Are there any others not visible, on the backside of the gearbox? If not, that just leaves a couple possibilities: a crack or casting flaw, or the drain pipe is leaking despite being well-tightened.

pack some absorbent pad in there, and watch the level. Add as needed. Will save you ever having to change it..... ;-)

Chasing oil leaks can be painful. Fortunately you don't seem to have a gusher. I presume you've wiped clean and determined it's leaking at the pipe. I can see the Teflon tape, my suggestion is a greater amount. Just be glad it's not an old British sports car or an early Harley because they deserve their reputation for marking their territory.

When its hard to see exactly where the leak coming from you can sprinkle some baby powder on the area and it will highlight the leak
.Any similar powder would work. Gold Bond may even kill that swarf rash.

If threads are npt running a tap in a little farther cleans them up

OK, less tongue in cheek. Good suggestions given. The baby powder one is great, but with and overhead leak it can be hit or miss. Clean up the area as best possible, drain the oil. Get a gallon of kerosene and add some AC dye to it. You can get cheap Dye kits at the auto parts store. Mix into the kerosene and pour it in. The Kerosene will find the leak pretty quick. With your IR light you'll see the leak really in no time. I seem to spend my life finding leaks and this always works for me. Also cleans out your sump. Don

rimcanyon said:

I looked for gearbox oil leak threads and found quite a few for square dial machines but none for round dial machines. Maybe there are some in larger rebuild threads, would appreciate any links to such if they might help.

The 1940 machine has a slow leak from the gearbox. There is evidence of the leak both in the motor compartment and from the weep hole below the bed. Here is a picture that shows the leak. Under the drain pipe is a layer of oil. This is not a recent leak, I have had it since I bought the lathe in the 1990's.

View attachment 297083

I tried to solve this by removing and reinstalling the drain pipe two or three times, but no luck. As the photo shows, the sight glass is below all other openings to the gearbox, at least in the front, other than the drain pipe. Are there any others not visible, on the backside of the gearbox? If not, that just leaves a couple possibilities: a crack or casting flaw, or the drain pipe is leaking despite being well-tightened.

Click to expand...

Since you have a Sundstrand machine and your base is different than the MG and WiaD machines, this may or may not be helpful: Some MG round-dials have an overflow tube that takes excess oil from the headstock and dumps it a depression under the quick-change gearbox. The gearbox is sloped to a drain hole directly under the spindle, that lets the oil drain into the chip pan. Here's a photo that shows the depression (drain pan) on a piggyback MG machine:


I don't know if you have the overflow tube or if your base even has the drain pan. But the oil you see may be coming from the headstock and finding its way to the drain pan. Some earlier machines only have the one drain hole in the center instead of the five shown above. It's not uncommon for the drain hole(s) to get plugged or painted shut so they won't drain. (Several of mine were painted shut.)

Cal
---

If you determine that there might be a porous spot in the gearbox casting, there is a possible fix.
My main 'expertise' is in vintage car engine and drivetrain repair or restoration. The castings for both aluminum and iron in the pre-WWII era were often porous. A very good enamel insulating and sealing paint called 'Glyptol' was used to paint the inside of the engine crankcases, transmission cases and rear differential cases..

This product is also an insulator, and as such is the red 'paint' we often see on the field and armature windings in electric motors.
This 'paint' is pretty amazing. I HIGHLY suggest wearing latex glove when dealing with this product.. Because if you get it on your skin, and IMMEDIATELY wash it off with solvent, you will STILL have a red stain in your skin that has to 'wear away', it usually takes several days!!

For the possible porous casting in your gearbox, I'd drain, flush, and wash clean with a good solven like Xylol, Acetone, Brake-Klean or similar strong solvent,, Glyptol will soak into the castings surface, but if there is heavy oil remaining in the porous areas, this oil might slow or stop the migration of the Glyptol into the flaws as far as possible..

The best price I've found for Glyptol is from a couple of aviation online sales sites. Best was around $55/quart. It does go a long way. For your Gearbox you need about a tablespoonful .

If the casting is broken at the pipe-threaded drain hole, Glyptol can be used as a 'pipe'dope' or sealant, instead of the teflon tape. The stuff is a great thread sealant too. It will find it's way into the crack and seal it as well as the threads themselves.. Just do not over tighten the drain pipe: Snug it up, and give the Glyptol a few days to dry or 'setup' .

DualValve

I'm not sure it is apparent from the photo I posted, but the drain pipe hole in the gearbox is mis-aligned slightly. It is one of the only machining errors I have seen on any 10EE, so probably it was not deemed critical. However, if you look at the photo, you can see that the drain pipe is supposed to pass through a channel milled in the bracket that supports the speed control cable for the Sundstrand drive. On this machine, the pipe contacts one edge of the channel, because the hole is angled back slightly. When I got the machine in the mid-90's, It had the leak, and I found the misalignment, so I ground off the corner of the channel to give the pipe clearance. The original pipe had a crack in the threads as a result of the misalignment (which torqued the pipe as the pipe was tightened). I thought I had solved the problem, and installed a new pipe (actually one from my parts lathe). But I continued to have a slow leak, and reinstalled the pipe a couple of times with teflon tape, the last time being a couple months ago. It still had a slow leak.

A couple days ago I drained the gearbox again and replaced the steel pipe with a brass one, and used some Loctite pipe sealant in addition to teflon. The steel pipe may have had a crack along the seam, very hard to tell. The brass pipe's threading was longer than the steel pipe's, so I think mlud's insight was correct. So far no evidence of a leak. Keeping my fingers crossed.

Cal, there is no drain pipe on a 1940 headstock. My lathe bed is leveled, and oil that collects on the top of the base casting does not drain quickly at all. Still have a pool under the gearbox.

Don, thanks for the suggestion, I will use an absorbent pad to get the oil out.

DualValve, thanks for the reply. If I ever remove the gearbox I will follow your suggestion.

One of these days I will probably remove the speed control cable to work on the Sundstrand drive. When that happens, I wil remove the cable bracket and remachine the slot ¼" wider. There is still just a bit of contact.