'96 Force 120 sat 5 years, feels locked up

[Maxum21]

hey, today i acquired a 96 maxum with a 120 merc force. The owner told me it worked fine last time used, but has sat for approx 5 years since. I pulled the hood and with light pressure tried to turn the flywheel by hand but it wouldnt budge. I plan on pouring some trans fluid in each cylinder and letting it sit a few days. Is there anything else i can try? since the motor feels locked, is it already damaged at this point?

 

[Frank Acampora]

Re: '96 Force 120 sat 5 years, feels locked up

They all ran when put in storage!

Forget the trans fluid. It may work but it is not likely. And even if it does free up the engione you will still have abrasive rust inside.

Your success will depend upon the degree of rust inside the cylinders. At minimum you need to pull the head and examine each cylinder. It is likely that there was a water leak. As long as the engine wass run regularly, the water did not have a chance to rust the liner. As soon as it was put in storage, rust developed and locked the rings to the cylinder liner.

You may get lucky and only need to hone out an affected cylinder---then again-----

Pull the head and post a couple of photos.

 

[Maxum21]

Re: '96 Force 120 sat 5 years, feels locked up

i dont get it... ive heard of guys with outboards sitting 5, 10, 12 years, that sprayed oil down the cylinders and within a few days had them running. i was somewhat optimistic with this motor but it seems as if the odds are against me lucking out.
i'll pull the head and post some pics. thanks

 

[Frank Acampora]

Re: '96 Force 120 sat 5 years, feels locked up

You have heard of engines sitting for a long time. Every trashed engine ever sold was running when put into storage. And every boat sold goes 45 MPH. The check is in the mail, I'll respect you in the morning. etc.

OK! here is a relatively simple but long-winded example and explanation:

I once bought a Chrysler 12.9 that had been laying without the hood, in a field on its side for at least 5 years that I know of. I needed to cut out small trees growing through it in order to free it. After getting it home, I cleaned and set the points and --vroom-- she fired up first pull. However, that engine did not have water intrusion and had most likely been run enough to have a good coating of oil in the cylinders.

When I bought my Chrysler 140, it was locked up. The boat and engine was for sale in a marina and had only been sitting for a couple of months. When I got it home, I pulled the head. The bottom cylinder had a light coating of rust that was locking the piston. When I pulled the exhaust cover, I discovered that there was a break in the gasket and water was spraying into the bottom cylinder. If the engine was run every week, the water would not have time to form enough rust to jam the piston. HOWEVER: After sitting for a couple of months, there was sufficient rust to stop the engine from turning over.

In this case I was lucky. The rust was light and tight, not flaking, so I was able to hone it out and use the same piston and rings.

Now, My buddy takes jammed engines and oils the cylinders. Sometimes this frees them BUT--although the engine is free and now runs, he has not examined the inside. Initially there will be some abrasive material left inside, and service life of the engine is reduced. Obviously I don't agree with his half fast methods.

You may be able to free the engine by oiling the cylinders but you would be much better off to at least remove the head and see exactly what the problem is---that is, if you intend to keep the engine.

If you take the time to do it right the first time you will avoid further problems later on.

 

[Maxum21]

Re: '96 Force 120 sat 5 years, feels locked up

thanks for the info Frank. i'll post some pics when i get the head off. Now assuming theres some light surface rust in the cylinders, what would be the next step? in other words how do i remove the rust? do i need to pull the whole powerhead and have the cylinders machined/honed? it would be like almost doing a complete rebuild, wouldnt it? and yes i agree, i would rather do it right from the start..

 

[Frank Acampora]

Re: '96 Force 120 sat 5 years, feels locked up

Well, mind you: If the rust is only from exhaust ports up and is light, you can actually hone it out with the piston at bottom dead center. You must, however be fanatic about cleaning the cylinder of all abrasive residue. Then oil with TCW-3 and replace the head.

That is what I did on my 140 (I was in a rush to get the boat on the water) and it ran very well for one season. However, at the end of the season it did melt two pistons necessitating a rebuild. I bored all four cylinders .010 over. Played around and accidentally got the timing at 42 instead of 32. Melted all four pistons to some degree. Aluminum throw off shorted the plugs before major damage was done but I replaced all four pistons again.


Let's wait to see the photos.

 

[Maxum21]

Re: '96 Force 120 sat 5 years, feels locked up

here are some pics of cylinders... what do you think?

 

[Maxum21]

Re: '96 Force 120 sat 5 years, feels locked up

there are a few spots of very light rust. if i run my finger over it i can notice it doesnt seem too bad at all. however i do understand that any rust is never a good thing

 

[Frank Acampora]

Re: '96 Force 120 sat 5 years, feels locked up

I think that engine has a lot of life in it if you do a little work. The rust does not appear to be heavy or flaking, although it is very difficult to see the cylinder in shadow..

Use some 400 grit and your hand to scrape out the heavyest rust and possibly free the pistons. Then clean well and move the affected pistons to bottom dead center. Hone them to remove all the remaining rust. Clean well before going on to the next cylinder.

Replace the head, start the engine and have fun.

If you want, take a ride--couple of hours depending upon what part of Jersey, I am West of Philly--And I can guide you in the process.

 

[Maxum21]

Re: '96 Force 120 sat 5 years, feels locked up

Frank, that would be great..

what do you mean when you say replace the head? replace the headgasket or a whole new head as well?

i'll shoot you a pm

 

[Frank Acampora]

Re: '96 Force 120 sat 5 years, feels locked up

No, I meant put the head back on! You can re-use the gasket if it is not damaged. You will see if the sealing rings have cuts or kinks in them and the gasket itself should not show any burned areas.