Water in BF75 lower unit

K

kotzebuecdory

New member
Folks,
Was changing the fluids on our 1996 BF75 yesterday in prep for some long trips coming up. I noticed that there was a small (1"x2") puddle of gear oil below the VENT plug. Somethings up here! So I pulled the drain plug next and got about 1/2 cup of water before the oil came out (looking milky and nasty of course). Engine/L.U. were running fine though....
I bought this boat/motor used (300 hours on it - 1996 model). I also noticed that there was no sealing washer/gasket on the vent plug (gaskets on level and drain plugs though).
QUESTIONS:
1) Is there supposed to be a sealing washer/gasket on the vent plug?
2) Could this (possibly) missing gasket be the culprit for the leak?
3) What are the other possible leak paths for the water into the lower unit?
Any help is appreciated!!!!
-Thanks
"Taiyaaq" 22C-Dory Arctic Cruiser
 
Sealing washers on lower unit fill and vent plugs -- yes.

There are seals below the water pump, where the driveshaft goes into the gear case -- also where the shifter passes into the gear case -- and, where the propshaft rotates in the spider nut, and around the outside of the spider nut. That much water could be the result of really loose vent and fill plugs, although I would suspect that the seal below the waterpump, and the one where the propshaft passes would be the more likely culprets.
 
Hi,
There are fiber washers on the plugs inthe lower unit. I have had one split and fall of before, you can buy them at the local hard ware store they are 1/4 in. I keep some extras in the boat kit just in case. I would also pull the prop and check for fishing line that seems to be the way most seals get dameged. mine did the same thing and was line. Althou a missing seal on the vent plug could let in water. There is quite a bit of water pressure when running, not to metion a slight vacume as the lower unit cools down. If you have to tear into it get the manuel only about 25 bucks and whorth ever cent.
Richard
 
After you check for fishing line and/or obvious leaks at the prop shaft seal, I'd refill the unit and operate it for 5 hours or so, and drain and re-check the lube for water.

You'll probably have a very slight amount of residual moisture, and this will be a chance to get rid of it and refresh the lubricant.

If there's a lot of water again, you know you've got a problem beyond the plug gaskets.

An outboard shop can pressure test the lower unit if desired.

Replacing the prop shaft seal and the others isn't all that complicated if you're handy and have the shop manual.

Another fun mechanical project! (as opposed to electrical/fuel/computer problems which can be difficult or impossible to diagnose and fix for us amateurs).

Good Luck! Joe.
 
Thanks for all the great info, folks! I've found a suitable gasket for the vent plug and will take her for a spin in the next couple of days. Going to take a look behind the prop too to be sure. I'll let you know how it turns out...hopefully that's the cure...-Matt
 
UncleRichie":3mvx0s77 said:
Hi,
get the manuel only about 25 bucks and whorth ever cent.
Richard
Click to expand...
Where can I get the manual for 25 bucks?
The Helm site lists the BF 75 manual for $76 +S&H , and the BF 135/150 @ $120. (!)
 
Back
Top