Fix the Force 120 or buy the Mercury 115 ???

[batman99]

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Got a 1996 Bayliner with Force 120 HP engine. I think this engine needs reeds and it probably needs its 2 cylinder rebuilt as well (due to broker reed leaf ???). re: All PSIs are 150 and this Cylinder #2 is consistently 120 (way past the 15 PSI variance range). Thus, a top end tear down and new rings (maybe larger piston ???) is required.

Down the road, the guy has a used 1992 Mercury 115 HP (with its controls) for sale. It has consistent PSI of 125s-128s in all cylinders, has setup on stand for viewing / testing, and is a good price. Its more than I wanted to pay for it but when all is said and done (and after selling broken Force 120 for parts), it might be a better "reliability deal" than rebuilding the Force 120.

With above in mind…. Should I rebuild the Force 120 or bolt on the 115 Merc? If wondering, I have a 1996 Bayliner 1700LS - that can easily support a 120 or 115 OB with ease (assuming similar OB engine stock length)?

thanks

 

[jbjennings]

Re: Fix the Force 120 or buy the Mercury 115 ???

JMO,
I'd rather put money into the merc 115, which will very likely have more power and speed than the force 120. However, I'd not plan on the MErc being a bolt on and go motor. Rarely are used motors that way. check the lower unit oil after running it at least on the muffs. Keep in mind, they all run good on the muffs, anyway, and you won't know for sure how it runs until after you test it on the boat at the lake.

 

[Jiggz]

Re: Fix the Force 120 or buy the Mercury 115 ???

If #2 Cylinder is the only issue, I'll probably just do the rebuilt. A wiseco piston costs around $125 plus $15 for the wrist bearings. The reed leaf are not that expensive either. And you do not have to replaced them unless they are broken. If they are just bent, you can always flip them over. If the cylinder head is still good you can also reuse it to save $40. You will spend another $15 for the carb and vee-block gaskets and buy ($25) or rent a honing kit to de-glazed the cylinder.

The other expense is a bore gage which you can probably rent from auto stores. You obviously have to bore gage it to ensure you have the right piston size. The entire work can be done in a day assuming all parts are on hand before you start. Now if the cylinder needs a re-bore then you might want to consider the 115 Mercury because now the rebuilt costs just more than doubled.

 

[Faztbullet]

Re: Fix the Force 120 or buy the Mercury 115 ???

Go with the Merc as its a looper engine and will twice as good as the 120, and use less fuel!!!

 

[batman99]

Re: Fix the Force 120 or buy the Mercury 115 ???

Thanks for everyone's feedback.

If wondering, I'm not good with internal engine stuff. I can replace the reed leafs (done that on 2-stoke ATVs) but when it comes to pistons, blocks and honing out, that's stuff is way over my head. Thus, I'd have to contract this level of work out.

My wife suggested I change its reed leafs (where needed) and drive until she blows. With low compression in one cylinder, it might last another year. And, it might not. But if she blows, then I would replace with a Merc 115 HP OB engine. Was ttold "with Merc Controls" with Merc 115 engine, it simply bolts on. Only fussing that's needed is steering connection and ignition wiring. Luckily, I'm great with wiring diagrams and wiring connections. Or, perhaps we sell the boat/motor and replace with different - like a 18/20 ft OB replacement?

Hard call - especially with my limited internal engine skills....

 

[roscoe]

Re: Fix the Force 120 or buy the Mercury 115 ???

You have one lower cylinder, but it is certainly not too low to run.

Is there a broken reed petal?

You may just have a stuck ring.

Probably pull the head and do a thorough inspection of the head/piston/rings.
Spray up the rings with solvent.
Put in a new head gasket.
Do a decarb with a can or two of Power Tune.
Then run it.
You may get 10 years out of it.

You're already talking like this is a throw away parts motor, so what do you have to lose?

 

[Texasmark]

Re: Fix the Force 120 or buy the Mercury 115 ???

Take the Merc. As Steel said the loop charging will make a tremendous difference in your operating costs...As Frank said, all Forces are cross flow charged and it is no way near as efficient as looping. BTDT Besides I think it is a much better engine. I have a 90 hp of the series.

Mark

 

[batman99]

Re: Fix the Force 120 or buy the Mercury 115 ???

Moved reply to different section...

 

[CharlieB]

Re: Fix the Force 120 or buy the Mercury 115 ???

........ The reed leaf are not that expensive either. And you do not have to replaced them unless they are broken. If they are just bent, you can always flip them over..

Never, EVER, turn a reed over. They are high grade spring stainless steel and once 'flexed' in one direction, reversing them often leads to embrittlement and failure.

Since they are NOT expensive, if you have ANY doubt as to reed sealing, replace them.

Otherwise I have to agree with most of the postings.

IF you want to spend the money, the Merc is a solid engine and will out perform the Force any day, anyplace.

But then again, that Force can be repaired at a very reasonable cost.

So it all boils down to your wallet, and how much do you want to spend.

If you are leaning towards the Merc, also consider that any used motor, it would be wise to plan on a water pump kit, fuel pump kit and complete carb cleaning with rebuild kits.

Spark test before you buy to ensure the ignition is fine, running on the hose it could have a few dead cyls and most wouldn't even notice.