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.

 

[lgaytan]

I'm changing the gasket this weekend, does anyone knows the torque spec for the bolts? Also should I put silicone or a gasket maker?

 

[jimmbo]

deleted

 

[Texasmark]

I'm changing the gasket this weekend, does anyone knows the torque spec for the bolts? Also should I put silicone or a gasket maker?

I'd clean up the threads on all screws with a wire wheel. If you have a set of "Taps and Dies", clean out the holes in the block....carefully.

You are screwing into a small diameter cast aluminum threaded hole. Don't get overly enthusiastic. If I were doing that job, I'd put all the screws in finger tight. Then start in the center opposing holes and with a wrench that fits in the palm of your hand, pull those screws down snug. Then making an X start working your way out to the tips with the same pressure. Then come back with a little more pressure and repeat the process.

Put the engine on muffs and check for leaks. If you have any adjust the tension on the screws in that area just until the leak stops.........this is much easier than having to repair a stripped out hole in the block!!!!!!!

 

[racerone]

On 1/4-20 screws the torque is 60 / 80 INCH LBS

 

[Chris1956]

Look at the markings on the heads of the water jacket cover bolts. They are likely grade 5. Look up the torque spec for a grade 5 (or whatever they are) for a 1/4-20 bolt and see what it says. Torque the bolts from the center out, tightening the center ones, then the next "row" up and then the next "row" down, until all are tight.

OK Racer has it for you.

 

[lgaytan]

Thanks I found this on internet, I will not put sealant or gasket maker as according to what I've read if the cover is flat out should not require. We will see tomorrow.

 

[lgaytan]

Fixed thanks for the help, I torqued as the diagram no sealant, I got a little drop around the thermostat so just re tightened there and issue was solved. I noticed the upper spark plugs tip was with rust, so it is clear to me the issue was water getting into the spark plugs cable and causing issues. I didn't bring new spark plugs so I just used sand paper to clean them and it worked, will be changing the spark plugs next trip.