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Oil leak Mercury 6hp 4 stroke 2005 - corroded oil pan!

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puklars

New member
Hi all,
I have a Mercury 6hp 4-stroke, my2005. This motor also comes in Mariner, Tohatsu and Nissan "costume", afaik.

During last summer, the outboard has been leaking a tiny bit of motor oil. This has gradually worsened to become a pouring oil leak at the end of the season.

I removed the powerhead from the rest of the outboard, and immediately found the leak. It was the oil pan itself that had corroded - nothing wrong with seals or gaskets here.

IMG_8910 (1).jpg


Have you had the same trouble? The oil pan looks to be made of cast aluminium. A new oil pan is around 230 USD - so I'm aiming at repairing mine. What repair method would you recommend - some chemical metal compound like jb weld, or maybe take the pan to a shop welder? The cast aluminium material looks porous doesn't seem to be ideal for proper tig welding - and everything is pretty tight with gasket surfaces just half an inch away from the hole...

Here's the hole from inside the oil pan:

IMG_8918 (1).jpg

All the best,
puklars
 

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fastjeff said:
I hear Yamahas have that problem as well. Hard to believe, but...

Jeff
Click to expand...

Really? Well, seems there is a widespread quality issue here...

Anyway, when (and if) I succeed in repairing the oil pan, I will replace the zinc anode on the gear case - for what it's worth.
 
I have the same issue at exactly the same place. My engine is a 2009 Mercury/Tohatsu 6hp. It developed an oil leak. When I took the power head off, I saw a the corrosion hole at the bottom of the oil pan. I wanted to post this, even thought the OP is 2 years old. The corrosion hole was right next to the raw water inlet pipe, as seen in the pics above. A good tig weld will render it stronger than the original. BTW, buy the Tohatsu gasket kit, it contains every gasket and seal for the engine and it costs about 50.00 USD. Mercury charges 150.00 for same kit.
 
199135s5 said:
I have the same issue at exactly the same place. My engine is a 2009 Mercury/Tohatsu 6hp. It developed an oil leak. When I took the power head off, I saw a the corrosion hole at the bottom of the oil pan. I wanted to post this, even thought the OP is 2 years old. The corrosion hole was right next to the raw water inlet pipe, as seen in the pics above. A good tig weld will render it stronger than the original. BTW, buy the Tohatsu gasket kit, it contains every gasket and seal for the engine and it costs about 50.00 USD. Mercury charges 150.00 for same kit.
Click to expand...

Thanks for sharing this. I bet you are a saltwater user like me? Something tells me that freshwater boaters will never see this issue on their motors.

With my loctite "metal epoxy" compound fix, the motor has now been used through seasons 2016 and 2017 without any notable leak. Yet... but when/if it happens again, I will make sure to tig weld it too.

I think I paid around 60 or so USD for the Merc gasket set at a local Swedish retailer.

BR/ puklars
 
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