Suspect Hurth 50 gearbox problem

[Caer Urfa]

After being out all day and running the engine I see what appears to be some 'pink oil splashing' in the bilge bottom and side area of the gearbox (on the starboard side).
The oil would 'appear' to be from the gearbox but there is little sign of change of oil level when dipstick level is checked.
Splashing appears to be coming from between the back of the gearbox and the engine interface.
Is there a seal here? possibly wearing? engine has done only 600hrs OR can this be caused by overfilling the gearbox in the first place.
Appreciate any ideas gents.

 

[earlybird]

The Hurth 50 oil capacity is fairly small, oil loss is likely to quickly show on the dipstick level. If your box really is losing oil at the rear of the engine then it could be the oil seal on the input shaft. AFAIK, this is a fairly unusual problem, but it can happen. The seal is easy to change by removal of a retaining plate, without stripping the box. The hard bit is separating the box from the engine to get access. You may have to split the flywheel housing from the engine block.

 

[AndrewB]

There is a drain plug underneath the Hurth, on the side opposite the gear shift lever. Looseness or failed washer here is the commonest leakage problem.

Second up suspect is a loose dipstick.

It just might be that some of the bolts holding the two halves of the casting together are slightly loose. From memory there are 6 on the smaller Hurths, 8 on others.

Overfilling is likely to encourage any incipient weakness, specially at the shaft seals. As Earlybird says, this is unusual. I think the Hurth 50 holds 0.3 litres of ATF. Measure with the dipstick pushed, not screwed in.

Check also that the unit doesn't seem to be overheating in use. The ATF is not supposed to reach more than 80degC, but usually is lower.

 

[mollyoxford]

I was very surprised at how little these gearboxes hold (having bought 2 litres of ATF!!!). We overfilled and then had to let most of it back out again...

Hmm, now this woudl be if interest in my own issues - what IS the best way of getting at the gearbox innards. Can you generally just split the box without having to drop the propshaft out? Or is it all boat dependent.