Odd Crack In Lower Unit

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keithmaryq

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Jun 5, 2010
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What started out as a small crack (and stayed that way for quite some time) has really taken on a life of its own. Any idea if this can be repaired, or how close I am to an oil leak?

2000 Suzuki DT 115
 

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99yam40

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Re: Odd Crack In Lower Unit

normally they drill the ends of crack to stop it and then weld it, but I have never seen one in that location before.
Usually it comes from the prop area and runs forward
 
L

lakensea

Chief Petty Officer
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Jan 30, 2002
Messages
542
Re: Odd Crack In Lower Unit

I would say the speedometer pitot hole got plugged and the water in the channel froze. You should have the gearcase dissasembled to check if the passage is cracked to the inside also.
 
stylesabu

stylesabu

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Re: Odd Crack In Lower Unit

not a bad guess but we don;t know where he lives. i think there is enough metal there that it can be fixed but you need to do it now
 
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robert graham

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Re: Odd Crack In Lower Unit

I'd wire brush it to the bare metal, then have it welded, file/sand/paint....from the photo looks like something hit it from that side?
 
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TomRay

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Re: Odd Crack In Lower Unit

I have a problem and do not know if it is repairable or a replacement situation. This is a Yamaha 90 two stroke of around late 80s to 1990 vintage. Pictures:

cracked-lower-running.jpg

and

lower-unit-crack.jpg

Any advice appreciated.
 
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99yam40

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Re: Odd Crack In Lower Unit

A good machine shop could probably fix it, but lower unit will have to come apart to be welded and then machined for the sealing areas before putting back together. But is just an opinion.
 
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robert graham

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Re: Odd Crack In Lower Unit

I'd say saltwater corrosion got around that bearing carrier and expanded, broke it out...maybe look for good used/rebuilt lower end to bolt on there?
 
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TomRay

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Re: Odd Crack In Lower Unit

Interesting comment from an old mechanic buddy: ignore it. He said the crack appears to be outside of anything important and lots of old Yamaha's have similar corrosion cracks, sometimes resulting in the piece falling off. I imagine that would interfere with water flow to the prop.

He said I might run with it like that for years. I really don't have in mind keeping this motor that long. I'd prefer a Tohatsu TLDI or Evinrude Etec to extend range on a single tank of fuel.
 
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99yam40

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Re: Odd Crack In Lower Unit

Looks like it will be getting into the lube soon and then you are in trouble
 
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robert graham

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Re: Odd Crack In Lower Unit

TomRay said:
Interesting comment from an old mechanic buddy: ignore it. He said the crack appears to be outside of anything important and lots of old Yamaha's have similar corrosion cracks, sometimes resulting in the piece falling off. I imagine that would interfere with water flow to the prop.

He said I might run with it like that for years. I really don't have in mind keeping this motor that long. I'd prefer a Tohatsu TLDI or Evinrude Etec to extend range on a single tank of fuel.
Click to expand...
Well, you might be able to "ignore it", but maybe not go too far off-shore with it like that!;)
 
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grid

Petty Officer 1st Class
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Oct 29, 2002
Messages
232
Re: Odd Crack In Lower Unit

Re: 2000 Suzuki--this is not an unusual damaged area, an it happens without hitting anything. You aren't in danger of entering the gear lube, but I'd spend the $$ removing the leading edge, grinding out the corrosion, and--if you can get it done reasonably--weld the old piece back in place. It depends on how much is left. You may just have to fabricate a leading edge out of J-B Weld, fair it and paint it.
Re: Yamaha--the propshaft carrier is assembled with no lube (to speak of). Corrosion builds up between the carrier and the housing and breaks the metal. Like the Suzuki, this is not uncommon. Seems they'd both spend a nickel on grease...Anyway, the carrier has to be removed, reducing the pressure on the gearcase itself. The carrier needs to be cleaned of corrosion. The carrier needs to be ground out along the crack and welded, then everything reassembled. You, too, aren't near the gear oil, but you're both getting close.
 
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TomRay

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Re: Odd Crack In Lower Unit

robert graham said:
Well, you might be able to "ignore it", but maybe not go too far off-shore with it like that!;)
Click to expand...

The boat is a 15 Whaler and it never leaves the Charlotte Harbor/Pine Island Sound area, always well within my towing insurance area. A failure might be inconvenient, but not dangerous.
 
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TomRay

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Messages
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Re: Odd Crack In Lower Unit

robert graham said:
Well, you might be able to "ignore it", but maybe not go too far off-shore with it like that!;)
Click to expand...

The boat is a 15 Whaler and it never leaves the Charlotte Harbor/Pine Island Sound area, always well within my towing insurance area. A failure might be inconvenient, but not dangerous.
 
T

TomRay

Seaman
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Messages
64
Re: Odd Crack In Lower Unit

grid said:
...
Re: Yamaha--the propshaft carrier is assembled with no lube (to speak of). Corrosion builds up between the carrier and the housing and breaks the metal. Like the Suzuki, this is not uncommon. Seems they'd both spend a nickel on grease...Anyway, the carrier has to be removed, reducing the pressure on the gearcase itself. The carrier needs to be cleaned of corrosion. The carrier needs to be ground out along the crack and welded, then everything reassembled. You, too, aren't near the gear oil, but you're both getting close.
Click to expand...
My problem is that I lack the skills to do those things and this is an old, rebuilt, corroded engine to which I am not attached at all. I really want a Tohatsu/Nissan TLDI for the enhanced fuel economy, but bought this one when the old Mercury died because it was cheap.

I don't want to spend a lot of money on it. Actually, I don't want to spend any. I want to save up for a better engine, and if this one hangs on a bit longer, it will have served its purpose.
 
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robert graham

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Re: Odd Crack In Lower Unit

TomRay said:
The boat is a 15 Whaler and it never leaves the Charlotte Harbor/Pine Island Sound area, always well within my towing insurance area. A failure might be inconvenient, but not dangerous.
Click to expand...
Heck, just run it and enjoy it...it might last as long as you need it to. A 90HP on a 15' Whaler!....guess you've got plenty of power?!;)
 
T

TomRay

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Re: Odd Crack In Lower Unit

robert graham said:
Heck, just run it and enjoy it...it might last as long as you need it to. A 90HP on a 15' Whaler!....guess you've got plenty of power?!;)
Click to expand...

It's rated for 70, which is the same weight 3 cylinder engine in the two stroke lines. The 90 was cheap and available and is nice for slalom skiiing. That's my excuse and I'm sticking to it. ;)
 
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