Whilst the 180 is not a model available in the UK or Europe I think its necessary to clarify several things.
Taking your message in stages; 'overfilling the engine compartment with oil'. Are we talking about the sump (oil pan) here? If the engine is filling with oil and assuming the correct amount has been filled there are 3 usual possibilities.
The fuel lift pump (assuming its a diesel) is the most likely cause. The diaphragms perish with time and allow diesel into the oil.
Secondly the seal in the main fuel pump can be leaking fuel into the engine oil as it has gone hard with age and wear.
Thirdly and a strong possibility is the power steering pump. Again the seal can go hard and/or split allowing steering oil into the engine. You do not mention that you have to keep topping up the steering oil.
If there is oil entering the clutch housing this can come from the seals on the shafts which enter the gearbox or indeed a loose or cracked Multi-Power pipe in the clutch housing. It could also come from the MP spool assembly but this is rare.
You mention 'filling up the dry cavity and then pushing hydraulic oil into the engine'. The chances of oil being forced into the engine are remote. It would have to be forced past the rear crank seal. Any oil present in the clutch housing should drain through the split pin in the bottom of the housing. Make sure that the split pin is in place and free. If necessary remove the inspection plate from under the housing. Reach in and clear any debris around the split pin head.
If any significant quantity of oil was entering the clutch housing you would soon see the clutch slipping through contamination. You will also see oil leaking that has been thrown into the starter motor or at least dampness around the starter.
Whilst the inspection cover is removed use a flashlight to inspect the clutch assembly for any signs of oil. If it should be a MP pipe you should be able to see any leak using the flashlight. KEEP YOUR HANDS CLEAR OF THE APERTURE.
Please come back with a little more specific information.
DavidP, South Wales