Hurth 50 on Perkins m30

[Trenail]

I have found thick sludgy brown oil in the gearbox. Several atf oil changes have not cleared it..
Should I flush out with an overfill with parrafin.?
Which seal is likely to have gone?
This is not a good time of year to be thinking of an engine out or worse !

 

[Boater Sam]

Did you think a seal had gone to let the oil in from !somewhere"? There is no where it could have come from, certainly not the engine.
The gearbox should be full of oil to level. Later ones are advised to use ATF but it seems to make no difference.
You have probably a mixture of both!
Do NOT flush with paraffin. If you feel that you must flush use detergent flushing oil.
Refill with 10w 40 engine oil.

 

[Trenail]

Did you think a seal had gone to let the oil in from !somewhere"? There is no where it could have come from, certainly not the engine.
The gearbox should be full of oil to level. Later ones are advised to use ATF but it seems to make no difference.
You have probably a mixture of both!
Do NOT flush with paraffin. If you feel that you must flush use detergent flushing oil.
Refill with 10w 40 engine oil.

Thanks.
I had thought of a failed seal letting in engine oil but am not sure if this if likely to be the route.
I have been using Dextron ATF oil ad recommended elsewhere.