Head Gasket Replace, 1998 Mercury Force 120hp

[jerryjerry05]

Oh no!!!
You'll need to remove the top 2 pistons and then buy me a new car.
Kidding, the passage is the exhaust and it should go straight through to the lower unit.
Take the prop off and after it's back together, run it and the screw should come out where the exhaust exits.

If you go for the top line? A Camaro or F350 Superduty will work

 

[Themanofsteel]

jerryjerry05 Ha Ok. Your help has been worth a new car.

 

[Themanofsteel]

That I can see, the lower portion of the cowl is not removable without removing the engine. Am I wrong? Will I need to remove and lift the engine block to get to the bottom screws?

 

[Themanofsteel]

Also before forget do I need a torque wrench for exhaust chest to? And should I use lock washers on the nuts.

 

[pnwboat]

You might be able to remove the bolts that hold the bottom pan in place so that you can shift the bottom pan over a bit..... just enough to get a wrench on the bottom bolts.

 

[jerryjerry05]

You'll just loosen it and move it to the side.

I think the torque is like 70 inch pounds.

The torque is so light I think the lock washers wouldn't really help.

 

[Themanofsteel]

Two screws broke off at the bottom so I’ll need to tap and retread them. I need to lift the engine to get to them. What do I need to know before doing that.

 

[jerryjerry05]

You mean take the motor off the boat?
Or remove the head?

If you remove some stuff on the other side of the motor, you should be able to move the bottom
cover enough to access the screws(maybe)

Removing the powerhead, much bigger job, the lower unit and back cover needs to be dropped .
Then the air intake under the carbs comes off, makes it easier to access the screws/ bolts.
One hidden nut over the rubber exhaust.

The motor with the exhaust tube is about 3 ft. long. So lifting can be fun.
Don't remove the exhaust as the screws WILL break. I've never had all 4 come out without breaking, EVER

Take pics and lots of them.

 

[Themanofsteel]

Don’t see how it drops?

 

[jerryjerry05]

The head should just lift up.

 

[Themanofsteel]

Should I put gasket sealer on the exhaust plate gaskets?

 

[Themanofsteel]

Also. When I lifted the engine, there was what looked like a gasket. Do I need to replace that?

 

[jerryjerry05]

Yes on the last 2 .
When the motor was new and the edges of the metal were sharp and clean,
the factory gaskets had sealer and when new it was enough to seal it.
Now after time and expansion/ contraction, the edges don't seal as well and sealer is needed.

The base plate gasket 43008--6 is on e-bay 8$ to 20$ I sillycone the exhaust jus in case.

 

[Themanofsteel]

So I reassembled the exhaust plate and chest but I used gasket maker instead of gasket sealant not realizing they are different. At least that’s what I read online.

Can I get away with that or should I redo?

 

[jerryjerry05]

Use it, won't hurt a thing.
I really doubt you'd be able to clean them anyway.

 

[Themanofsteel]

So after reassembling everything, I've run the boat on the hose for a few day and everything seems great. The boat idles way better and starts easier. I'm going to take it out on the ocean today for a run.

 

[Themanofsteel]

Took it out on the ocean today for several hours and it idled and ran great. Never ran so well.

 

[jerryjerry05]

Thanks for the update.