[Yanmar Transmission] Help me assess first day out on my new (old) boat. I am a bit confused.

[Alan Gomes]

Alan, honestly the boat feels really dry inside. I definitely think that IF there has been high water in it, it would have been years ago, which would also not make too much sense. I will reach out to the old owner and ask. I think he is honest and maybe will shine light in my gear box conundrum. BTY, thanks for clarifying the oil type I should use in the gear box. Same in the motor crank, correct?

Well, I guess that it may just remain a mystery. You've done what you should do for now by chainging out the oil several times and then topping off to the proper level. Just run it and see what happens. It may be just fine. Those transmisssions are really simple little beasts. (Regarding the proper level, see my earlier comment in this thread about how to use the dipstick with this transmission.)

Yes, you can use straight 30 wt. in the engine, per the manufacturer. You can also use a multiviscosity weight, such as 15W40, also per the manufacturer. Currently I'm using 15W40, though I've used straight 30 wt. in the past. Your call. For the gearbox, though, definitely use straight 30 wt. In all cases, make sure the oil is rated for a diesel engine.

 

[acubria]

I went to the boat on Saturday. Extracted the gearbox oil one more time (5th I think) because the oil still looked a bit white-ish. Added 250ml of new oil and after testing a bit while still attached to the slip, I decided to take her out to the bay. Everything worked really well. Forward, backward, no weird behavior. I think that having all that oil mixed with water (at least 1/2 liter) was stopping the cones to properly engage with the gears. ( as explained in that video I posted earlier in this thread ). Going again tomorrow to do further motor testing and some sailing.
Where the water came from in the first place, remains a mystery to me. I will be checking the level and color of that oil over the next months to monitor further water intrusion. Thank you everyone for your advice and ideas. I think I dodged the bullet this time!

 

[Alan Gomes]

I went to the boat on Saturday. Extracted the gearbox oil one more time (5th I think) because the oil still looked a bit white-ish. Added 250ml of new oil and after testing a bit while still attached to the slip, I decided to take her out to the bay. Everything worked really well. Forward, backward, no weird behavior. I think that having all that oil mixed with water (at least 1/2 liter) was stopping the cones to properly engage with the gears. ( as explained in that video I posted earlier in this thread ). Going again tomorrow to do further motor testing and some sailing.
Where the water came from in the first place, remains a mystery to me. I will be checking the level and color of that oil over the next months to monitor further water intrusion. Thank you everyone for your advice and ideas. I think I dodged the bullet this time!

Very good. You may be OK.

By the way: My hull number is #209, so our boats were produced very close together.