Yamaha F75 lower unit water leakage

[22zuni]

I recently found myself in need of an impeller replacement, which I did successfully. I reattached the lower unit as instructed and bolts are tight and greased. I put on the ears, ran the engine with water and the pee hole works strong. However, I'm getting water leakage between the lower unit and engine on the transom side of the lower unit (photo attached). Feeling it with my finger, it seems notched like it is suppose to exhaust water at that point. Is this normal? Thanks.

 

[rejesterd]

I think you're good. If it was spraying out of there strongly, I wouldn't like that. Remember there's no seal at the seam between the lower unit and the upper case.

However, you shouldn't grease the lower unit mounting bolts. Those should be coated with loctite (the blue, non-permanent kind, unless you can find #572 easily). If that's not noted in your Yamaha service manual, it should be. Might not be a bad idea to re-mount it and just take a peep at the water pump housing when you drop it an inch or so. As long as the tube is lined up to accept water from the pump and the shift shaft lines up with its mating point, you're good.

 

[rejesterd]

Oh.. and looking closer, isn't that just your speed sensor inlet? When you move through the water, water flows into it, but when on the muffs, it will come out there, sure.

 

[Mohawkmtrs]

rejestered: i agree...you can see the small hose in the upper left of the picture.

Water is coming out the pitot hole (part of the boat's speedometer).

 

[racerone]

Well -----running on muffs there should be no water coming out of the pitot / speedometer hose on the lower unit !!

 

[22zuni]

Thanks all. The speedo makes sense alright but I think I will drop lower unit just a little and check it. About the Loctite, I had it on the counter at the Outboard shop and they were the ones that said grease instead. I thought Loctite too.

 

[rejesterd]

The service manuals I've read all say to use loctite. I've used grease in the past and didn't have a problem, but there is definitely a risk there imo. Grease prevents seizing, but it lubricates.. that's the opposite of what you want for mounting bolts. Unless you don't change your impeller for another 10 years, then you'll have no issue dropping it and breaking the loctite.

 

[TownsendsFJR1300]

Your speedometer pitot tube opening is much lower, on the leading edge. You should be able to just see/feel it.. Side note, it does help to flush it(if used in salt water), if not it will corrode closed..

The manual does say to use a loctite on those bolts but as you probably found, removing them was probably very tight and they weren't loose.

Simply cleaning the threads/bolts up and re-installing dry (again if used in salt water) is a happy medium. You won't have to wrestle with loctite(the bolts aren't going anywhere) and you removed the corrosion so again, it'll hold tight.