1975 johnson 70hp water in cylinder

emdsapmgr

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You may need to remove both exhaust covers and the gaskets. Get some new gaskets and re-install. Make sure you use a sealer and re-torque the bolts after the engine goes thru a couple of heat-cool cycles. A common failure and an easy fix.
 

F_R

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Yep, a common problem, has destroyed many a motor. Usually, the inner exhaust cover baffle plate will be found to be warped in the area of the exhaust ports. You can throw gaskets at it all day and it will still leak unless you do something about the warped plate.
 

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emdsapmgr

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I've seen those inner exhaust covers that have porosity (holes) in the casting.
 

F_R

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Look at the picture I posted. Water and exhaust areas separated by a thin and leaking gasket area. Yes, water pressure sprays it through the leak and into the exhaust ports. It is also wetting the piston skirt when the ports are closed, and that water works it's way into the crankcase where it rusts and destroys the bearings. As I said, has destroyed many a motor. Including my own father-in-law's motor---TWICE! First one was replaced under warranty, scrapped it after the second time.
 
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