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Old 30 May 2013, 10:07   #1
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small hole in gearbox

I have found a small hole in my gearbox today, have no idea where it has come from, could it be cavitation? hopefully its more like it has hit something submerged.

anyway do you think water will have got into my gearbox, or is this just an outer shell, the engine is 2007 mariner 60hp 4 stroke.

also can i fix it with some chemical metal? as you can see from the pic the hole is pretty small.


Thanks
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Old 30 May 2013, 10:17   #2
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Clean it out, chemical metal to repair it then change the gearbox oil to be sure. Oh, and check your anodes.
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Old 30 May 2013, 10:22   #3
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I would have thought a weld would be a permanent repair, but first drain you oil to check the colour, amount and check for debris
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Old 30 May 2013, 10:35   #4
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If I'm reading that pic right it's on the leading edge?

I bet if you look somewhere under the outsiode of your cowl (or halfway up the leg) you'll find a small rubber hose possibly with a cap in the end - it's a pitot orifice for a speedo - means you don't need a separate pitot hanging off the transom.

Mine has it too. I just parked a short length of hose over the fitting in the top of the gearbox (only visible when removed from leg) and filled other end with sikaflex.


(and if you decide to fit a speedo to it, be aware that the Teleflex ones read slightly down if not used with their own transom mount senders - the "streamlining" of the leg gives a slightly lesser pressure and so you need a Merc / Mariner guage to get a half sensible reading)
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Old 30 May 2013, 10:44   #5
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No need to worry

That is the water pick up hole for the pitot tube which is the transducer for the speedometer if connected.
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Old 30 May 2013, 11:18   #6
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What 9D280 and Ribochet said.

Most people have problems with keeping this hole open to get speed readings. It would be kind of ironic if you filled it in.

jky
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Old 30 May 2013, 11:20   #7
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thanks for all the replies guys, so are you saying that hole is meant to be there? if so i'm such a muppet never noticed it before

i shall go and hang my head in shame
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Old 30 May 2013, 11:58   #8
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Quote:
Originally Posted by surfer4life View Post
thanks for all the replies guys, so are you saying that hole is meant to be there?
Yes - cavitation will only cause erosion on the prop itself and electrochemical corrosion would not result in a hole there

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if so i'm such a muppet never noticed it before
i shall go and hang my head in shame
No need for all that - this is what the forum is for - ask away
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Old 30 May 2013, 12:14   #9
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I thank you all very much for the help.

i do feel like a complete idiot though for not seeing it before, i've owned it for a year! Ah well, you live and learn
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Old 30 May 2013, 12:37   #10
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yep, tis a pitot hole
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