125 HP fails to rev up

[jimmbo]

For decades, Mercury, on its Inline Engines, had no removable Cylinder Head. Removal of the Water Jacket Cover on one of the older inlines, and you would see this. That changed on the V6s. Your Engine is like the 1st Gen, no Head, but might look a little different with the Jacket Cover off

 

[lgaytan]

For decades, Mercury, on its Inline Engines, had no removable Cylinder Head. Removal of the Water Jacket Cover on one of the older inlines, and you would see this. That changed on the V6s. Your Engine is like the 1st Gen, no Head, but might look a little different with the Jacket Cover off

View attachment 416614

Thanks for this pictures this clears my mind a little bit I guess it seems everything is casted together in iron or some material as that, this means this can withstand better over heating? The jacket cover still aluminum I guess.

 

[racerone]

Why do you doubt this?-----There is no cylinder head that you can remove !!-----Pistons go into a blind hole from the other end.-----The block and the dome with the plugs are ALUMINUM.----Cast iron sleeves are inserted in the cylinders.

 

[lgaytan]

The only doubt I have is that by this leak the engine doesn't rev up as water is not getting into the pistons, but again seems feasible that water getting into the plug cables can cause bad or non spark. Just trying to understand the issue.

 

[racerone]

Water does not get near the piston from this leak!----Replace this gasket and test run.---Simple job.

 

[Texasmark]

Replacing the Gasket, may or may not result in fixing it. The Water Jacket Cover may have warped, if it ever had gotten too Hot. I replaced the Gasket twice on one of my motors, lasted longer when installed without Sealer. Replacing the Water Jacket Cover solved the problem.

Since the water jacket cover plate is a non-functioning element of the engine block, and you are sure its what's leaking...usually around the spark plug openings, if you lay the cover on a flat surface and it appears to be warped, just add more gaskets and glue between them......is what I'd do.