Gearbox temperature

[MARNEN]

Hi I have recently re fitted my Yanmar 2GM20 and am interested to know the temperature on the outside of the gearbox after running the engine in gear for say half an hour. It feels quite hot and I have no idea if it is OK or not . I will measure the temp later today but so far I have been unable to find any info re what is acceptable.
Many thanks in advance for any help offered

 

[RichardS]

I assume that this is a shaft drive fitment.

Assuming the correct amount and type of oil is in there, the only reason I can see for any overheating would be some kind of misalignment, which is not an issue for a saildrive. If your shaft turns freely in neutral and there is no sign of misalignment at the coupling when the shaft is turned, and there are no untoward noises when the engine is running, then I can't see that there can be any overheating, whatever temperature it's running at. It's more likely to be heat being conducted from the crankcase.

Richard

 

[vyv_cox]

Typical operating temperature for most gearboxes, not necessarily marine units, is 55 - 60C oil temperature. Seals are probably good for 100 - 120C and the oil a little more.

 

[MARNEN]

Thank you for the helpful responses gentlemen.
I ran the engine today and out of gear the temp on the outside of the gearbox was 35c after 40 mins. After engaging gear it rose to 45c after a further 40 mins and seemed to be constant. I did find some further info in a manual as a caution before working on the gearbox let it cool as it could be as high as 90c. So it would seem to be all good .
Thanks again.