Transmission dipstick leak

[Philip R 2]

Long story short, I bought a fully rebuilt 78 c-141. the week I got it home, it wouldn't drive, narrowed it down to gear oil in the transmission and not 10/30 MO as needed. Drained it, and extensively flushed it, and filled it with 10/30 and installed the recommended 1410 Napa oil filter. Ran fine most of the summer, but the past few times I cut its been pushing oil up out the dipstick tube. this last time it started shutting down because of lack of fluid, went to check the levels and it spewed oil up the tube and spayed all over. I'm assuming she got a little hot, but still can't figure out why it's pushing oil out. Any insight into why it's doing this?

[Ed Kennell 38,181]

to the 

 

Sounds like there is still some of that heavy gear oil  causing a problem.     I would flush it again.

[Brockport Bill 1,662]

you don't specify if its a gear or hydro tranny?

[lynnmor 7,307]

 

Sounds like you are overfilling.  Are you running at full engine speed while mowing?  Does this tractor have a cast metal fan or a plastic fan on the transmission and is it tight and spinning without slipping?  Are the fins on the transmission completely clean?

 

There is no system to shut down the engine due to overheating, please explain.

[Philip R 2]

7 hours ago, Brockport Bill said:

you don't specify if its a gear or hydro tranny?

Sorry, hydro

[Philip R 2]

4 hours ago, lynnmor said:

 

Sounds like you are overfilling.  Are you running at full engine speed while mowing?  Does this tractor have a cast metal fan or a plastic fan on the transmission and is it tight and spinning without slipping?  Are the fins on the transmission completely clean?

 

There is no system to shut down the engine due to overheating, please explain.

I filled the transmission to the proper level, even after running for a while, i repeatedly checked to make sure levels were still correct because of air in the system. I only run the tractor at full throttle regardless of what I'm doing. It does have a cast drive fan pulley on both the transmission and hydro pump, and both are clean. I also pressure wash the entire tractor after each use. Someone suggested that the "vent" may be plugged but I don't know what vent they are referring to. And when I say the tractor shuts down, I'm referring to it no longer moving due to lack of fluid in the system. 

[Gasaholic 224]

Sounds like oil is foaming up - might help to know whether you have a sundstrand or an Eaton (If original, I'd suspect Sundstrand) but if the oil is a bit overfull and starts cavitating it can foam up (creating air bubbles) and like a shaken up bottle of pop, spew out the tube when dipstick is popped out. The difference between Full and Full to the top (as in overfull) is very small, so oil foaming (Air getting into the system somewhere) can build up quite a bit of pressure (In one case, enough to push the dipstick out of the fill tube!)  If it had gear oil in it , I'd probably suggest changing oil and filter again to help flush that out of there, and refill with a high quality 10W30  - We also used Dextron 2 / Mercon ATF (Ford Spec back when you'd have ATF made for most other cars, and then a different ATF Spec made for Fords.) in some Sundstrands, - We had to be careful to not mix the 2 (10W30 with ATF) as they were incompatible (and ATF at the time was a bit cheaper) but then started to standardize and we'd refill after rebuilds with 10W30 only, phasing out the ATF machines. (We'd never just drain and then refill with 10W30 as mentioned, residual oils were incompatible) 

 

So, in short, I'd say change your oil yet again (and filter) and try to let it drain completely as possible, and when you go to fill it (If I recall it took about 5 quarts) do not fill to the full mark quite yet , and let oil settle a few minutes after hitting the bottom of the dipstick (up to the "Add" mark) , then jack up rear end and run tractor a minute, putting motion lever through its paces slowly until wheels drive and operate smoothly, then shut off, re-check and re-fill back to add mark, rinse and repeat until it STAYS at the add mark , then you can top it off JUST to the full mark on dipstick (but not over) 

 

Frankly I am surprised your hydro survived being fed Gear oil.   and if your machine stops moving because of a lack of fluid, given it is a Sundstrand, most likely, be aware there is also another oil filter internal to the case that is only accessed and replaced by separating the hydro from the axle case. (It is a steel mesh filter with  magnet on the end of it) - If that filter screen is getting plugged up, that'd cause your problem right there - hydro is trying to suck in oil that won't flow through the mesh screen. 

[pfrederi 17,741]

If it is a Sunstrand the vent is in the fill cap (5/8" square).  Look for a small spot in the flat top surface that has nodular brass in it. Make sure it wasn't painted over.

[Ed Kennell 38,181]

16 minutes ago, Gasaholic said:

 

So, in short, I'd say change your oil yet again (and filter) and try to let it drain completely as possible,

 

9 hours ago, Ed Kennell said:

to the 

 

Sounds like there is still some of that heavy gear oil  causing a problem.     I would flush it again.

Yes,flush with diesel first to try to get all that heavy gear oil out. It could be causing a restriction thru the internal screen filter or worked it's way into the newly installed oil filter causing a restriction.

Raise the front of the tractor to help in getting all of the oil out that is trapped by the hump in the bottom of the tranny.

Edited August 17, 2023 by Ed Kennell

[lynnmor 7,307]

It does seem like the oil is thinning when hot and a worn Sunstrand pump may slow or stop working.  Also, pressure washing after every use is something I wouldn't do, it is quite possible to blast water inside the transmission as well as into areas that will have debris and cause rust.  While it is best to drain oil immediately after shutdown, this time I would jack the front up several inches and drain after sitting overnight to see if some water comes out first.  I don't know if you have the same dipstick as the 1100 series hydros but they use a small opening thru the loop to vent, that loop is often crushed or plugged with dirt.

[Ed Kennell 38,181]

1 hour ago, lynnmor said:

1100 series hydros but they use a small opening thru the loop to vent, that loop is often crushed or plugged with dirt.

Thanks neighbor.    All the 1100s I have had and I never knew this.    I just blew the dirt out of my current three with carb cleaner.  Guess I was just lucky I never had a 1100 burping problem.

[Philip R 2]

3 hours ago, Ed Kennell said:

 

Yes,flush with diesel first to try to get all that heavy gear oil out. It could be causing a restriction thru the internal screen filter or worked it's way into the newly installed oil filter causing a restriction.

Raise the front of the tractor to help in getting all of the oil out that is trapped by the hump in the bottom of the tranny.

Do I run it with the diesel in the case, or just pour it in, put it in push mode, and manually work it through the system?

[Philip R 2]

For now I will diesel flush the system, then flush with another full gallon of 10/30 with new filter, then after about an hour, change oil and filter again. Thank you for all of your feedback. I will keep this thread posted on progress

[Ed Kennell 38,181]

6 minutes ago, Philip R said:

Do I run it with the diesel in the case

Yes,  jack it up and run it at idle RPM through the full forward / reverse range.    Hold each wheel from turning.  The goal is to flush the gear oil from all the gears, screen filter, valves, etc.

[Philip R 2]

So, it's been a few cuts, I only filled the case to 3/4 full, worked the system to make sure fluid worked it's way through the pump and hydraulic lift, and there is still a bit of residual oil pushing out the tube still. After the first flush of oil from the diesel flush there was a bit of black crud dripping from the filter port, i didn't investigate, but I'm assuming its broken down gear oil from the flush. I'm going to assume that another oil flush would be recommended soon to make sure all the diesel got flushed out. But aside from the little bit of oil that pushes out after each cut, the tractor is functioning normal. Thank you all for your help and input.

[lynnmor 7,307]

How would you know that the transmission is only 3/4 full?  Do you mean 3/4 of the safe area on the dipstick?  Did you check to see if the vent in the dipstick is clear?