1999 F50TLRX lower unit nipple

[ChuckB1954]

I removed my lower unit to replace some seals because I am still finding water in the gear oil, even after replacing the prop shaft seals.. There was no hose (#18) or nipple (#19) connected to the nipple (#17), which was there. I can see there is a hole in the upper casing right above the nipple that apparently the hose exits the lower unit from. Where does this hose go from there and what is it's purpose? Would having no hose allow water to get in the gear case?

nipple.JPG


EDIT: After continually searching I discovered it is for the speedo. Since I don't have one fitted, I guess I can ignore it...

[99yam40]

Drain the lube and pressure test the lower unit to find where it is leaking.
service manual have info

[TownsendsFJR1300]

. I can see there is a hole in the upper casing right above the nipple that apparently the hose exits the lower unit from. Where does this hose go from there and what is it's purpose? Would having no hose allow water to get in the gear case?




EDIT: After continually searching I discovered it is for the speedo. Since I don't have one fitted, I guess I can ignore it...

Correct.. That line / hose is for the speedometer water pressure. On the very leading edge of your LU, you'll feel, (and barely see) a very small (approx 1/16") opening which IS the pick up for the speedometer(and the rest of those parts).

As you noted, water should travel thru there and won't affect the oil inside the LU.

Just as a side note, that leading edge opening clogs up(especially with salt water use) and keeping it flushed (if using the pressure speedometer) will keep the speedo working correctly...


Wasn't it you (perhaps not), that changed out the upper seals (in the removable block), and the top seal was set too deep into that block (blocking off the oil passage)? If so, beside doing a pressure test, I'd be re-setting those seals..


.

[ChuckB1954]

Thanks for the info. I can ignore the speedo nipple as I have no speedo. I did remove the water pump and found that the two inner seals looked. which according to the The lips were facing outward,parts diagram is correct. I know the PO said he replaced them when he did the water pump. They look new and are undamaged.I might order new ones anyway. The two prop shaft seals go in the same way as the fore mentioned, with the lip outward. It seems to me that doing the pressure test is a little tricky if you don't have a regulated air source. It wouldn't take much to blow past the seals with their lips facing outward. I still have to check the shift shaft seal, but it is pointless as I am ordering new ones. I am still confused as to how the water is getting in.

No Scott, that wasn't me, as far as I can remember anyway.

[99yam40]

yea a mighty vac hand pump/vac is a good thing to have access to

[ChuckB1954]

yea a mighty vac hand pump/vac is a good thing to have access to

Oh.. I see.. I am suppose to create a vacuum and watch the gauge.. not pump air in.. I should have known.

[TownsendsFJR1300]

I made a set up that screws into the LU with a low pressure air gauge and SCHRADER valve. You can use a bicycle air pump (low volume and very contr00ed) OR one of those 12 volt, portable air pumps. Those take a little bit to fill the air space. (Not likely to over pressurize or blow out seals..)

Make sure you turn both the drive shaft and prop shaft, (NO oil inside) when checking for leakage.



And what I referred to earlier, someone put the two upper seals right up against each other. There should have been a space between the for the oiling hole to allow oil up there..
I don't remember who it was, just that it would prematurely fail..

.

[99yam40]

Oh.. I see.. I am suppose to create a vacuum and watch the gauge.. not pump air in.. I should have known.

no the hand pump can do either one, but you are using pressure on testing the lower unit

[TownsendsFJR1300]

Most (I don't have your manual) manuals call for pressure, NOT vacuum.


From my F150 Yamaha Shop manual:


Capture.JPG