Force 120 Outboard Low compression - rebuild it?

[Stretch72cj]

New to the forum and in the middle of a decision. Picked up a free bayliner in need of a complete interior overhaul but was told the motor ran great 4 years ago. Decision was to strip the interior and make a simple fishing boat or slowly restore it. Went through the restart process of lubricating cylinders, cleaning out old fuel etc. Attempted to start it and wouldn’t. Without investing too much I checked spark and so forth which spark is found and finally checked compression. Cylinder 2 is bad at 60. All others at 140. Bought a manual and have read through the repair process and keep wondering if it’s worth the hassle. Just curious if someone’s been here and done that and advice is welcomed.

 

[racerone]

Step #1 is remove cylinder head and have a look see.

 

[Stretch72cj]

Step #1 is remove cylinder head and have a look see.

Thanks. Was gonna be my next move if suggested. See if it’s the gasket or piston rings.

 

[jerryjerry05]

The head removal can be a B&^%H
Take your time and if the bolts don't come easy?
Use PB Blaster, Krol or any good penetrating oil.
A propane torch comes in handy too.
You can remove the port cover on the side and
inspect the side of the piston and see inside there.
I bought a snake camera $11 for my Android phone.
Works great for inspecting.

 

[Stretch72cj]

The head removal can be a B&^%H
Take your time and if the bolts don't come easy?
Use PB Blaster, Krol or any good penetrating oil.
A propane torch comes in handy too.
You can remove the port cover on the side and
inspect the side of the piston and see inside there.
I bought a snake camera $11 for my Android phone.
Works great for inspecting.

Thanks for the input. Hopefully tackle it this weekend. Fingers crossed.

 

[Redbarron%%]

The hardest part would easily ne getting it apart without breaking bolts etc. Heat, Kroil, cursing, and luck are needed.

 

[Stretch72cj]

Update is heads off. All 4 thermostat bolts and 1 head bolt broke. Survey shows gaskets good but all but 1 cylinder show terrible ring grooves. Pretty much what I expected to see. Interesting the owner said it ran great when they parked it.

 

[racerone]

Motor will have to come apart.----That damage will not just " buff out " I say.----They all run great according to most sellers.

 

[jerryjerry05]

The checks in the mail along with the other 2
greatest lies.
Before you go further maybe find a machine shop
that can do the work??
In my area I've found 1 place(50mi. away) that does that kind
of work. He works out of his garage.
Maybe fill out the profile and you might find your close
to someone on here that can help.

 

[Redbarron%%]

My experience from sleeving a 90 is that sleeving is probably too expensive, but boring and replacing pistons is not too bad.
Check with your machine shop.
Plan on $1000 total cost.
It all depends on the amount of material that has to be removed to clean up the bores and the size of pistons available.
It is possible that a free boat is too expensive.

 

[racerone]

A free boat can be expensive.-----But there is huge value in learning about these Bayliners and other boats.----Also known as " paperliners " by some.

 

[Stretch72cj]

Thanks guys. I had a lead on a 93 120 for a good price but someone beat me to it. Going to tear what I have down for a full inspection and rebuild what I have. Local machine shops are quoting 25$ a bore but that depends on how far they have to go. Hopefully I end up with a solid block to build of off. Seems like pistons are hit or miss on availablity too depending on oversize.

 

[jerryjerry05]

Wiseco pistons are usually the best bet.
You'll need the wrist pin kit and the rings
from Wiseco.
You should change all the rings.
Wiseco rings only fit Wiseco pistons.
I've found ebay is a good place to get
parts.
I've found that removing the exhaust cover
can be a big problem, I just leave it on after
a good inspection.
IF?? you do remove it the gaskets don't always
seal right unless you have the edges on the
block and cover milled down.


Fill out the profile and add your location.

 

[Stretch72cj]

Wiseco pistons are usually the best bet.
You'll need the wrist pin kit and the rings
from Wiseco.
You should change all the rings.
Wiseco rings only fit Wiseco pistons.
I've found ebay is a good place to get
parts.
I've found that removing the exhaust cover
can be a big problem, I just leave it on after
a good inspection.
IF?? you do remove it the gaskets don't always
seal right unless you have the edges on the
block and cover milled down.


Fill out the profile and add your location.

Thank you. Profile updated. I figured the machine work might need to be addressed. Hoping with how easy the head came off the rest will be decent to disassemble

 

[jerryjerry05]

90% will come right off.
The exhaust chest, the screws at the bottom, they've been setting in hot salt water for a LONG time.
They're 1/4-20 screws and I can guarantee at least 4 are gonna twist off.
Then trying to get the rest of the threads out is gonna be a B*&^H

 

[The Force power]

90% will come right off.
The exhaust chest, the screws at the bottom, they've been setting in hot salt water for a LONG time.
They're 1/4-20 screws and I can guarantee at least 4 are gonna twist off.
Then trying to get the rest of the threads out is gonna be a B*&^H

lol you mean; 90% break and to get to them you ether pull the power-head or the bottom-cowl

 

[Redbarron%%]

Let's see 16 -17 bolts and three break off?
Closer to 20% break off.
That is about right. and the Law of Aggravation says that they will be in the worst possible places.
When you replace them and operate in salt water stainless sounds like a good idea, but the stainless sets up corrosion that attacks and swells the aluminum and binds them worse than regular plated steel.
Some anti-seize might help as well.

 

[Stretch72cj]

I enjoy extracting broken corroded bolts said no man. I’m going to see what my options are. Appreciate the reply’s. Hopefully get to it this weekend

 

[The Force power]

Remember, if you don't have (already) broken bolts and/or the gasket is not leaking; you don't need to take it apart to replace the pistons/rings etc.

 

[Stretch72cj]

Remember, if you don't have (already) broken bolts and/or the gasket is not leaking; you don't need to take it apart to replace the pistons/rings etc.

I was thinking that same thing. Minimize the drill and burr time