Woods BB 720 with emulsified gear box oil

[Furu]

I have not used my Woods BB720 brush hog for a while so after hooking it up today I did some maintenance checks which involves among other things checking the gear box oil level. To my surprise the oil while not overfull was a creamy emulsified solution that is a dead giveaway for water infiltration. Of course Woods does not have a drain plug and the manual states to siphon out the oil if required. What a design!

Now my question.
I am waffling on putting diesel in to dilute the remnants and pump it out without any run then new oil for 10 minutes or so of running and then pump it out and put in more new oil and see what happens.
My other idea is to just put in the new gear oil run for 10 minutes or so and then pump it out then replace with new oil again.

I like the idea of using the diesel to clean out more of the remnants of the bad stuff but worry tht it might be an issue that just does not need to be done.

What are your thoughts

 

[hayden]

I think either approach is fine, but it begs the question of how the water got in there in the first place. Has some part of the gear box been submerged? I just replaced the input shaft seal on my BB720, but that’s because oil was leaking out, not because water got in.

 

[Furu]

I think either approach is fine, but it begs the question of how the water got in there in the first place. Has some part of the gear box been submerged? I just replaced the input shaft seal on my BB720, but that’s because oil was leaking out, not because water got in.

I just noted that I put BB 600 instead of BB720 not that it matters much. Can't change the title I guess.
Yes I have a lot of concern as to how and why as well. It stays out in the elements but has been out for 17 years without an issue. The only thing that I can think of is the vent plug. Don't know how they actually seal/vent but it has been exposed to rain but why did this happen now after being exposed to rain for 17 years. Never been submerged and based upon the oil level and the fact that the underneath is dry of oil it has not been leaking.

How hard was replacing the input shaft seal? Easier than the output shaft I would venture but a pain either way.

 

[kneedeep]

I would cut it enough to pump out with a drill pump then flush with diesel to finish.
Fill it with corn grease or Lucas

 

[Redbug]

I have a Bush Hog SQ-172 (if that makes any difference), and was checking the oil level one day before use and noticed when taking the plug out the air inside was under pressure. It should not be that way. I took the vent plug on top out and apart. There is a spring inside which acts as a controlled vent. I shortened the spring and no more higher pressures inside.

My guess is pressure buildup with weather changes or running it may have caused a seal to blow. I also keep a tarp over the gearbox to keep rain off it.

 

[ruffdog]

Water in the gearbox is going to settle to the bottom, where a siphon hose will never reach. The water will be down inside the output shaft bearing and lower seal. The only sure way of getting most of the water out is to tip up the mower so everything will drain out. Or, pull the lower seal.

 

[hayden]

The input seal is pretty easy to replace. Just remove the drive shaft, shield, and pull out the seal. When it’s out it will dump most of the oil. Maybe all, but I’m not sure. So that’s a good time to do any flushing because the only other way to drain the oil is to get the gear box in its side. It’s also check the vent, and maybe just replace it.

 

[ChrisFromWisconsin]

I'm not sure what weight oil you need, but what about if you use marine lower unit oil? That stuff can run with some water in it and remain lubricity. It doesn't solve the problem of how it got in there, but it would help prevent damage.

 

[hube2]

... it begs the question of how the water got in there in the first place.

If it is anything like my Woods tiller, then the oil fill plug has a breather hole in it. Any amount of time left out in the rain, combined with a little wind, is all it takes. I have to change the in both gearboxes on the tiller next spring for the same reason.

 

[hayden]

If it is anything like my Woods tiller, then the oil fill plug has a breather hole in it. Any amount of time left out in the rain, combined with a little wind, is all it takes. I have to change the in both gearboxes on the tiller next spring for the same reason.

Sounds plausible, though my BB720 has lived outside for 18 years and not a drop of water in the gear box oil. I don't know how it's different from your tiller. But I think these implements live outside much more than they live inside, so I would expect them to be immune to typical rain and snow.