1978 70hp Mercury Powerhead

[Rusta]

I have recently discovered a hole below No3 cylinder on my powerhead. I have been told that this can be repaired by means of welding. Can anyone advise as to whether this is a satifactory way of dealing with the problem. Welding is to be done by certified engineers. Any advice is greatly appreciated.<br /><br />Thanks from Down Under

 

[petryshyn]

Re: 1978 70hp Mercury Powerhead

>where exactly is the hole located?<br /><br />>what caused the hole to begin with (froze up, porous casting etc.)?<br /><br />>is it in the cylinder wall?

 

[Rusta]

Re: 1978 70hp Mercury Powerhead

Thank you for your quick response. The hole is located in a small hollow approximately an inch down from the spark plug. This hole is the size of a match head (roughly). The hole is not in the side of the cylinder. I have beeen informed that it is electrolysis that has caused the problem. Apart from the small(??) hole that is present the rest of the unit is in A1 condition.<br /><br />Thanks again for your help<br />Garry

 

[petryshyn]

Re: 1978 70hp Mercury Powerhead

I wouldn't hesitate to weld it in that area, especially to save the motor. . .

 

[alcan]

Re: 1978 70hp Mercury Powerhead

Hello Rusta<br /> The hole you describe is in the water jacket cover. If you remove it, a good tig welder could fix it. Did you look into the cost of replacing this cover? You might be able to find a good used one. Let us know how you make out. Good luck.

 

[Rusta]

Re: 1978 70hp Mercury Powerhead

Schematic & Alcan<br />Thank you for the positive notes you have sent back to me. I dont know how long the weld will last but to replace the power head for that particular motor was in excess of $AU3,000.00. Considering that I paid 3,000 for the boat,motor and trailer a couple of hundred dollars is a meer drop in the ocean.<br />I will let you know of the outcome.<br />Thanks again<br />Garry<br />HOBART,TASMANIA,AUSTRALIA

 

[petryshyn]

Re: 1978 70hp Mercury Powerhead

I took it that the hole was in the combustion chamber end of the cylinder. Heck, if its in the water jacket cover, I'd weld it at home! <br />How long will the weld last you ask..... It'll outlast the engine if done right. Just be sure to resurface the gasket face and check for straightness before installing. As alcan says, should be easy to find a used cover around. Go the cheapest route.<br /><br />good luck!

 

[Rusta]

Re: 1978 70hp Mercury Powerhead

schematic<br /><br />You are quite correct, The hole is in the combustion chamber end of the cylinder ,with my limited knowledge of outboard motors I have obviously confused Alcan, SORRY<br />I hope you are still right about the welding anyway.<br /><br />Many thanks for all of prompt replies.<br />Garry

 

[alcan]

Re: 1978 70hp Mercury Powerhead

Hi Rusta<br /> Thanks for clearing me up on your hole.<br /> But the answer is still yes. There are people that are as skilled as brain surgens with welding. The right person will cure your problem. Good luck.

 

[petryshyn]

Re: 1978 70hp Mercury Powerhead

Ditto alcan<br /><br />but be careful on the brain-surgeon welder thing.....LOL

<br />There could be some sensitive_____out there.

 

[Hooty]

Re: 1978 70hp Mercury Powerhead

Shucks gang, I'ed fix that with J-B Weld.<br /><br />c/6<br /><br />hooty

 

[Rusta]

Re: 1978 70hp Mercury Powerhead

Thanks for all of your extremely prompt and positive replies guys. It would be a pity to lose the old girl as it really pushes a 14ft runabout along at a great rate of knots. I will keep you posted on the outcome.<br /><br />Thanks again<br />Garry