Force 120 Blown Powerhead

[Themanofsteel]

So my powerhead blew on the way to Catalina.
• What are some reasons?
• Can it be fixed?
At one point we had a pretty big swell and the boat tilted sideways and the engine came out of the water and reved really high for a few seconds. after that the engine sounded different

 

[Themanofsteel]

I filled up with 48 gallons of gas and 1 gallon Mytik JT4 Outboard Premium engine oil. TCW3

 

[Themanofsteel]

My friend was driving at full throttle and fighting a pretty rough ocean. I feel like might have overworked the engine. Has 5 guys on my 22’ Trophy.

 

[Themanofsteel]

I’m seeing the piston connecting arm broke. I think I can find the parts for that but where can I find the Block Cover that has a hole blown in it.

 

[jerryjerry05]

Don't really know why it went?
But running at full tilt isn't good .

Didn't you just fix a water intrusion problem?
Possible the water got back into the rod and bearings.

As far as parts? I'd look for a new block or even a complete motor.
The damage on the inside could be a lot more than you can see?

They don't list the intake by itself , it comes with the block????? so no part #s

 

[Themanofsteel]

I purchased a new block. The drive shaft and 3 of the pistons are in good shape. I'm rebuilding the engine with the new block. A few questions...

1. One of the flywheel magnets broke a piece off when I was removing it. Will I need a whole new flywheel or can it still work.
2. When I reassemble the engine, will I need to do the timing on it?
3. Anything else I should know about rebuild and assembling the engine?

 

[jerryjerry05]

It will run with the piece of the magnet missing.
But if the one broke?? The others might be close to going??
Usually the timing doesn't change unless you completely disassemble the linkage.

 

[Themanofsteel]

We’ll i transferred the drive shaft to the new block so I had to disconnect the 3 good pistons and reconnect them to the drive shaft.

FYI The magnet chipped when I was pounding the flywheel trying to remove it from the drive shaft. It was really tough to get off.

 

[jerryjerry05]

Yup beating on the flywheel can do a lot of damage.
It tends to weaken the glue.
I use a 3 jaw puller and only hit the top of the threaded shaft.
They usually pop right off.

 

[Themanofsteel]

Ok. About the shifting rod. I removed the lower and the rod. Now when I put it back in I can’t find forward. When I twist clockwise I can turn the prop in reverse. I twist counter clockwise and hear a click and it goes to neutral. But can’t find forward.

 

[jerryjerry05]

You always need to add the year and model???
I'm guessing it's the later Mercury style gearbox.

If the shift rod doesn't get the right gear?
You might have turned it too far???

You'll need to remove the drive and experiment with different locations on the shift rod.
Turn it and try to find N then 1 tiny move L or R should lock it in gear.
I've found leaving the shifter in N and the shift rod in N helps.

They say leave it in F but just ONE tiny movement of the drive shaft knocks it out of gear

Get it up so the splines all match both drive shaft and the shift rod and before you tighten it?
Try shifting while you turn the prop.
You need to have the prop turning or the linkage binds.

 

[Themanofsteel]

1998 Force Mercury 120hp

 

[blackd]

I agree with Jerry. Neutral has been easier for me than in gear when installing the LU. I've also found that having the motor tilted all the way up lessens the need for giant's strength getting the LU adjusted and pushed all the way up. Once up loosely attach with bolts and then try the prop to assure it stayed in neutral and/or shifts correctly. If so tighten it up.

I don't remember if this has been covered yet, but adjusting the shift lever while installing the LU is best with the cable off. With engine tilted up gravity holding the LU in position with one hand while the other jiggles the shift lever helps get the beast installed and in the correct gear.

 

[Themanofsteel]

So when I turn the Rod clockwise, it shifts into Reverse. When I turn it counter clockwise, it shifts into forward BUT the slightest movement too far and it shirts passed Forward and into Reverse. This doesn't seem right to me. It's hard to get Neutral and Forward. Seems like it's default position is reverse.

 

[blackd]

If I'm understanding you, yes. It takes very little movement to shift. What you are moving is a small cam like piece with ~75% unused and the 2 or 3 lobes (my memory is failing on this) on it. When adjusting the cables on the shift lever you will notice just 1 - 2 turns makes the difference from clicking to free on the clutch. I think its because of the spring loading on the propeller shaft clutch mechanism. I'm just guessing here. Maybe Jerry will be able to better answer in the morning.

I remember it was PITA until I realized I was expecting more movement and after I got it aligned in neutral it fell into place with just the jiggling of the shift lever. You will need to fine tune the shift cable to remove any clicking in neutral, because clicking means the clutch jaws are touching.

 

[jerryjerry05]

You might be 180d off???
Try turning it past the area your in now.