Flushing Gear Housing

[bill-m]

What is the best way to flush out a gear housing so I can fill it with all new gear oil? I was thinking of using kerosine but don’t know if that would hurt any internal rubber parts. I’m still trying to figure out if I screwed up this lower end by putting the wrong lube in the gear housing. I have also not been able to find out what the extra hole next to the fill plug is for.

[PugetSoundBoater]

I would not flush the gear case. Just drain the old lube,let it drain all day if you wish,then refill with the correct lube. The extra hole is a water drain hole ,I see it has a bit of oil exiting the drain hole,no concern. It is a bit of unburnt fuel from the exhaust.

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[frankr]

Agreed, flushing is not normally necessary. But if you want to, then the kerosine or mineral spirits will be fine.

[PugetSoundBoater]

If i was going to flush the lower unit, i would probably turn the lower unit by hand a few turns only with the prop or recoil, then drain the kerosene really well,refill with the gear oil,run a couple hours to get it warm, Drain again and refill with the gear oil. You really don’t want any traces of kerosene in your gear oil.

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[The Boat House]

While 105 may not specified for you motor
it is used as a gear lube in many outboard
motors. Kerosene isn’t. To get the 105 out
all you need to do is warm up the gear case
with a heat gun. (not a torch) The 105 will run
right out. If you still feel the need to flush,
fill it with gear oil, run it a bit and drain.

[bill-m]

Thanks for the replys, I don’t have a heat gun so I will heat it up in the test barrel then let it drain on it’s own. I will fill it with gear oil and repeat the process and then give it a final fill before taking it to the lake again. The thing that bothers me most is the stuff coming out of the little drain hole in the first place looked like gear oil and not like the unburnt fuel shown in the picture. Hopefully if it happens again, it will happen in the test barrel and not after pulling it out of the lake. If it does happen again I will take pictures and post them for your opinions. Thanks again for the help!

[The Boat House]

The water surrounding the gear case in your tank
won’t let the 105 become warm enough to flow.
A droplight put right next to the gear case may
get it warm enough to flow but it will take a while.
Heat guns can be very useful if you’re going to be
working on these things. My good one quit and I
need one. I have a Harbor Fright close by so I
picked up one of their el-cheap-o’s. It’s made of
plastic and twice as big as it need to be. My old
one was half the size and had a plate where you
could set it down so you didn’t have to hold it.
(Allows you to burn the fingers on both hands
instead of just one.) I have every intent of
replacing it but it’s got to be going on 10 years
now and this el-cheap-o thing still works and I
use it all the time. I think if you decide to get
one you’ll find more use for it than you think.

[rudderless]

Hair dryer??

[The Boat House]

quote rudderless:

Hair dryer??

If the wife’s not home its a heat gun!!!

[bill-m]

Thanks guys! I have no wife but I did inherite my mother’s hair dryer 13 years ago so it will all work out fine. Thanks again!

[Author]

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