Oil & Fuel Hydraulics leaking into engine oil crankcase ?

[Mopower]

Hello-

I have a Mitsubishi Satoh s-370d Beaver and last summer I changed the engine oil and filter, cleaned the hydraulic oil filter and filled with new fluid, and it has been working great. Last night I pulled it out after sitting for the winter and was looking it over and when I checked the oil level it poured out ( way overfilled) , smells like hydraulic oil. So I drained it till it was at the proper level and found it was 3 quarts overfull and when I checked the oil level of hydraulics they were low. My question is how did this happen and what parts am I going to need to fix it (hydraulic pump, oil pump) ?
Other notes... After draining the engine oil to proper level the hydraulics quit working , so I took the extra 3 quarts and put into hydraulics and they worked again, operated them and let the engine run for a while and the oil levels stayed ok, seems to be a slow leak into the crankcase. Any help would be appreciated.

 

[Navasot]

So this is the first time its been checked since you serviced it? Have you operated it enough to be sure that is happening and the fluids were not drained or filled wrong?

 

[Mopower]

Hi Navasot-
I am the only one who operates and services it so I know nobody else would have overfilled it. This thing sat for a long time and we recently purchased the property and equipment, so first thing I did was check if it worked and changed all fluids and filters, I checked it periodically during the year while I used it for long periods of time ( mowing) , it would burn some oil and I would top it off, I expected it to be a little low instead its 3 quarts overfull. I'm new to fixing farm equipment and wasn't sure if its possible for the hydraulic oil to bypass into the engine oil through the pump ( seems that the hydraulic pump, oil pump and oil filter share an assembly). I will run it tonight and see if this happens again and how fast it happens.

 

[Leejohn]

Hyd. pump shaft seal.

 

[Mopower]

Thanks Leejohn, can I service the seal separately or have to replaced the whole unit?

 

[Leejohn]

I'm not sure about your tractor, best to check the parts manual.

 

[Navasot]

Im supprised its not running off on you though... most the time when this happens the engine will run off of the hyd fluid and you pretty much have to dump the clutch to kill it.

 

[Mopower]

I thought the same thing Navasot, I didn't run it for long before I found the problem and drained it to the correct level, looks like parts are hard to get for the 370 and will require a new hydraulic pump to fix it $400-$500 , I might try running it and just periodically checking the oil level.

 

[Leejohn]

If you can get the seal out just take it to a bearing and seal place , they should be able to match it. The O.D & shaft size and how wide it is, well work for them.

 

[oldnslo]

If you get the seal out check the shaft for wear to make sure the seal hasn't worn a groove in the shaft. Also would be concerned about condition of pump since most gear pumps have the shaft seal vented to the pump inlet so there should be very little if any pressure in the seal area.

Excessive slip or leakage of the pump can overflow this drain path which then pressurizes the seal chamber forcing fluid out.