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Ausfish New Member
Crack in motor cowling
The patient is a 140hp Yammie.
The symptom is a hairline crack in the metal work just in front of the prop.
I'm pretty sure it is a case of just welding it up but I need someone in the Wynuum/Cleveland/Capalaba are that I can trust.
Any suggestions?
Cheers
Fred
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Ausfish Addict
Re: Crack in motor cowling
are you talking about the gearbox area?
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Ausfish Addict
Re: Crack in motor cowling
G'day
Sure isn't a cowling problem, sounds like a gearbox to me.
Where to go local? I know there's an alloy fab. shop out the back of Mr T's in capalaba. May be worth a call.
Dave
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Ausfish Bronze Member
Re: Crack in motor cowling
I'd find out what made it crack b4 I went to the welder or to sea
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Ausfish Platinum Member
Re: Crack in motor cowling
if you cant get anyone i weld them up all the time! it is a common thing! have even had where the hydrofoil bolts onto break completely off and fall into the water, had to make up new one! anyway i do plenty work for boat yards we are located in redbank! pm me ! cheers shano!
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Ausfish Bronze Member
Re: Crack in motor cowling
phredo did my 90hp yamm 3 years ago and no probs since as nthqld has said yuo need to find out why in the first place. mine had been welded twice before so i found out why and fixed the problem. it turned out to be the ring nut inside the gear box it is an unusual alloy and dissimilar so when the bond is broken or not working on the lower leg the ring nut corrodes and this corrosion gives sufficient pressure to crack the gear case people say it is salt build up but it is not. my ring nut thread was very badly corroded 75% thread destroyed i cleaned it all up put it together with corrosion resistant grease then had to pin it in two places with all ally rivets bit unorthodox but worked a treat you must check and verify the integrity of your lower leg earth bond good luck
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Ausfish Platinum Member
Re: Crack in motor cowling
Agree fully with the post above, I had exactly the same problemm with a 200HP Black Max Merc.
The gland nut on the gearbox corroded so badly that it cracked the outer gearbox housing.
Mine had major surgery to get the gland nut out and the crack was then vee'd out and stitch welded.
Welding it up on the outside will only provide temporary relief if it can be welded at all, I think the oxides from the corrosion will prevent welding it without tearing it down.
A common fault on moored boats where the engine is stored up on an angle and the nut area ends up with a large salt build up as the saltwater evaporates and leaves the salt behind accumulating at the threads.
- Darren
Last edited by Mr__Bean; 17-08-2007 at 03:16 AM.
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Ausfish Bronze Member
Re: Crack in motor cowling
phredo my crack was 75mm long and i did it straight away so as to not allow any oxidation to occur in the crack i was able to weld mine successfully in situ wiyhout tacking the gear box apart welding with the same principle we welded live naptha lines at petro plants dont burn through but get max penetration hard but can be done used basic non-pulsed mig machine the previos two cracks some one else did with an ac hf tig would have neccessitated complete gearbox dismantle clean out of crack. as stated before i believe it is due to a bad earth bond the one on th lower leg i checked integrity of all bonds and found this one to have a higher resistance. i get .006 milli ohms when i cross the two leads of ny multimeter and this is exactly what i got on all bonds when i had finished the job still get it each month i check it now it is imperative you find the cause and i still believe it is crrosion between the ring nut/gland nut and gearbox housing not salt ingress
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Ausfish New Member
Re: Crack in motor cowling
Good on ya Guys,
You are right of course, it is the gearbox housing not cowling - sorry, I might have been red wine affected when I posted the thread . . . . hic!
I'll take all those suggestions/experiences onboard and get it sorted from the inside out.
Thanks again
Fred
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