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Overheating issues 1972 evinrude 125

M

mike007800

New member
Does water pass thru the space between the cylinder head and outer cover on front of head?
I peeled this off the head and it was covered in sediment. The water pump has been changed thermostat changed, heads water passages have no sediment but I thought i would take bolts of the top cover and discovered this. Does water pass thru this part I can't seem to find a spot where It would enter. Any other ideas as to why I am having overheating issues.
 
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Hi Mike and welcome. Yes that's a mess. Needs to be soaked in hydrogen chloride/muriatic acid....monitor progress, use gloves and clean by hand as deposits break down.
 
Wow!, that engine looks like its been run in the Bahamas its whole life... Major salt, not sure if I'd be dipping an aluminum cylinder head in Muriatic Acid though.
 
It doesn't pass between as that is just the gasket for the cover plate once you remove your old gasket you will see what you have to deal with by opening up/cleaning the chamber/passages. Once you begin reinstallation make sure your bolts are buffed clean with wire, also run a blunt end tap in all thread holes dress up head surfaces with wet sanding and straight backing surface. Use nickle anti-seize on them scantly to help replace/substitute the original zinc coating that was on the new bolts when they assembled it back a half century ago.
 
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If you need cylinder heads/bolts or depending on what you find, call Tim's Outboard in Hackensack Minnesota at 218682-2331 and they will help you, tell them that Tim sent you
 
My mistake.----The gasket does not need holes to let water through !----The gasket prevents water leaking out bolt holes and the perimeter.----The cylinder head side is cooled.
 
It's still plugged up and needs to be cleaned. There's no water circulating through that cylinder head with that impaction. This was before lost foam casting and it could not be made any other way in 1972. In 1985, OMC figured out the lost foam casting process and eliminated the need for that water cover design entirely. Get a dental pic and start picking.
 
30% muriatic acid is about max concentration, over the counter. I regularly clean steel fuel tanks with it. At this concentration it can be risky to soak aluminum delicate castings for too long so I recommend diluting with water to 20 or 15% or in other words cut it in half with water. You will be amazed at how nicely it helps break down the oxidation.
 
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