Seeking advice as to whether or not to ditch my Force

[scout-j-m]

As the subject line indicates I'm having trouble deciding where to go from here with my 1994 70HP Force outboard. My current situation is that I have both very low compression on all cylinders (110, 110, and 90 psi) and a faulty ignition which delivers a weak and inconsistent spark to the lowest compression cylinder. So basically this motor is about to die any day and just doesn't seem worth putting any money into to me.

It is powering a 1994 17' Spectrum Dominator. I still go fishing in it as the boat itself is decent in that it doesn't leak, has a good trolling motor and batteries, and has decent carpeting and decking. It would suck for it to die on me out on the lake but I stay within trolling motor range typically.

My predicament is whether or not to try to fix the Force up anymore to make it last me a few more years, ditch the Force and replace it with a used 60-70HP outboard, or try to sell the boat and Force together. I'm leaning option two as I don't see trying to fix the outboard as a very smart move and I'm not sure I could even sell the boat/motor together as it is without essentially giving it away.

There is a craigslist ad nearby for a 1976 Mercury 70HP with controls (no power tilt/trim) which is advertised as having power loss at WOT but says compression is 140 psi across all three cylinders and has new power packs and plugs. It also looks pretty sharp for its age. Is listed for $500. I really don't want to replace the Force with another project motor but anything that has good compression is enough to get my attention as it means I can likely fix it myself.

Just curious what members here may do in my situation...

 

[Jiggz]

Personally, this is what I will be doing before jumping into replacing the motor or selling the entire unit.
1. Borrow, rent or lease another compression tester to verify your initial readings. Each comp tester can vary up to 20 psi between models and made.
2. Remove the head and try to preserve the head gasket as much as possible and then inspect the cylinders for gouging.
3. Do a post mortem diagnosis of the gasket and the mating surface to see if there is any indication of leaks. If leak is from faulty gasket then just replace the gasket and hopefully that will fix your low compression problems.
4. After repairing the low compression numbers, repost your ignition problem on a different and separate post. But if you want to get started with that, you can start by validating the timing and doing the "Link and Synch" procedure.

 

[scout-j-m]

Thanks for the response.

That makes a lot of sense to try the head gasket first. If that would fix my compression problem that would be awesome. I won't get my hopes up though lol.

 

[Frank Acampora]

Remember the Latin phrase: Caveat Emptor---Let the buyer beware. Unless the engine is such a super cheap buy that you can't resist it and unless you are willing to gamble time and money to repair it, NEVER buy an engine (off craigslist especially) with any known problem.

First follow Jiggz' advice.

Force engines are not difficult nor expensive (relatively speaking) to repair. The Force 70 is a surprisingly potent engine and worth salvaging. If you really like your boat and if the engine does have problems repair is the way to go.

 

[Nordin]

Agree with jiggz and Frank, your comp.readings is not to bad. It can be your tester that reads low, the different between the cyl. not so bad.

I am not so familier with the 70Hp Force from the 90.s but think it has the Mercury ign.system....... pretty good system and you can find spareparts.
If you are a bit mechanical minded, troubleshot the Force before jumping in to an unknown 70.s Mercury.
Check headgasket, ign.system and the reeds, maybe decarbing will rise your numbers.
Of course at this forum we are fond of Chrysler/Force OB and give you advise to keep the Force but I am a "spare time" OB mec. and have worked on other brands as OMC, Mercury and the Japanees. So I have experience from those too.

A 70.s Mercury can be a nightmare, remember in those years Mercury did not have stainless driveshafts and a simple maintain as changing impeller can be impossible because of the shaft has been rusted in the crankshaftsplines.

Mercury powerheads are cast in one piece, no headgaskets that can leak, BUT the saltwater will corrode in the casting and many of them start to leak around the sparkplugholes ending up with water in the cylinders.

It is up to you to make your own choice.

 

[jerryjerry05]

If by chance the Mercury motor has been in or near salt water, I'd pass.
It's almost 40 and the screws or bots are probably pretty well frozen in place.
Like the others suggested a different comp tester. Hot battery and remove all of the plugs.
Spark tester? Move coils around and see if the weak spark follows the coil?
outboard ignition.com has test procedures.

It might be something simple?

I like my Forces. They're going on 27 and still run great.

 

[gm280]

I also would go for the repair option. Why? Because I enjoy making things work like new again and it would be interesting to learn about that engine. Buying any other used engine does not guarantee you won't have equal or worst issues with that one as well. I know what folks say about things when trying to sell them. Easy to talk, but who actually knows?

 

[gregmsr]

1976? I graduated from high school that year.....that was 75 years ago! (failed math)
I went down this road a couple years back...to keep or not to keep. Glad I kept it.
With advice from this forum, and patience, you can make that motor sing again and feel confident it will bring you home.
Gives me a sense of accomplishment to have went thru the whole process and hear the Force sing....
Forget what the anti-Force folks say...I have seen plenty of other brands being towed back to the dock...

 

[HotTommy]

scout,
The good thing about an engine you've given up on is that you can take it apart without worrying too much about whether you can put it back together. Consequently, you've got little to lose by pulling the head and visually inspecting the pistons/cylinders. If it looks really bad, you're no worse off than you were before. If you see an obvious cause that can be readily fixed, you'll be happy you found it. ... Go for it.

 

[Frank Acampora]

Here's the deal: Pistons cost about 150 each (On the high end. Many stock pistons can be had for less.) Boring costs about 50 bucks per cylinder. SO, the WORST case is if you need to bore all three cylinders and replace all three pistons you are looking at about 600 bucks if you disassemble and reassemble it yourself. No special tools are required and you can get all the help and instructions you need here at this forum.

Best case is that you will only need a 50 dollar head gasket.

In either case, the first time you fire up the engine you will have a sense of pride that you repaired it.

Compare the maximum 600-700 bucks you will spend to the cost of a used unknown history engine. And--Where are you going to find a good, running 70 for 700 bucks? It makes sense to repair.

 

[scout-j-m]

Man thanks for all of the replies. Yall really have given me a confidence boost to not give up on the ole Force. I like Hot Tommy's mindset.

I'll try to find another compression tester to borrow to double check with. Then I will pull the head and inspect it and the gasket.

I never considered doing a rebuild myself. I guess it would be something I wouldn't mind trying as it seems as if it would be good experience. Basically you just disassemble, haul the head to a machine shop to be bored, order new pistons and rings and install? Most of that seems straightforward enough although I'm not sure of all of the tweaks to timing and whatnot afterwards which make me nervous.

As for the ignition problem, I have tried to troubleshoot it in the past with no luck. The only time I got the motor checked out by a mechanic he said that the stator was bad. All I have really done so far is installed new plugs and wires, swapped coils around, and tried to test some ignition components with a multimeter which isn't the right tool for the job (peak reading voltmeter what's needed?).

 

[HotTommy]

scout,
I was in exactly the same spot as you with my Force 150 about this time last year I had never done more than remove, clean and reinstall a carburetor. Armed with a Factory Service Manual, lots of help (and parts) from folks on this forum, and a determination to get it running, I was able to replace a piston assembly, clean up a scratched cylinder, and replace damn near every electrical component. In the end it cost me about $1,000 in parts, but much of it is now new and I know what I've got.

I'll also echo what others have said about opting for an even older engine in uncertain condition. My limited experience showed that past a certain age, there is a very uncertain supply of used repair parts.You could find yourself in a situation where you can't get a needed part for any price.

 

[Frank Acampora]

If it develops that you do need to rebuild, you can expect to spend about 10 hours disassembling and a like time reassembling. As you do it more frequently, time is reduced. While I have done a number of Force engines and can practically rebuild them blindfolded, I recommend that you take your digital camera or smart phone and take a couple of photos before starting work and a bunch during the process. Anything you think you may have a question about later. You can't take too many photos.I do this ANYTIME I rebuild a different brand like Suzuki, Yammy, and even some Mercs. I'm not proud and know I may need to photos as a reminder of where things went--especially wiring.

 

[jerryjerry05]

You don't need a Peak Reading Volt meter to test the stator.
Go to outboard ignition . com and read the instructions.
The PRV is needed later in the testing and usually you can figure it out before that.

 

[scout-j-m]

You don't need a Peak Reading Volt meter to test the stator.
Go to outboard ignition . com and read the instructions.
The PRV is needed later in the testing and usually you can figure it out before that.

Thanks jerryjerry. I forgot about that site. I think in my initial tests I used may manual. That site does have good instructions though.

BTW, in the event I need an ignition component, are their parts the way to go? They are definitely much cheaper than the OEM parts I have seen.

 

[HotTommy]

I got several of my ignition/electronic components from cdielectronics .com .

 

[jerryjerry05]

Yes I use their stuff.
Look around on Amazon.Sometime they sell stuff real cheap.

 

[scout-j-m]

I got several of my ignition/electronic components from cdielectronics .com .

Just looked them up. Coincidentally their HQ happens to be just a few miles from where I work in Huntsville, AL. If I purchase ignition parts I will definitely use them to buy local and maybe save on shipping costs.

 

[shane12970]

Scout i live In Jones Al. Thats about 40 min from Prattville. Im new to this forum too. Im replacing my 40 hp johnson with an 85 hp force on my pontoon.. Good luck and i may be asking questions soon