1991 Force 70HP No Compression on #2 Cylinder

"Hi, my name is James and I&#3

"Hi, my name is James and I'm new to this discussion board. I recently bought a 1991 Bayliner 1700 with a Force 70 on it from a private party. I noticed right away that it was not spitting water from the holes on the back of the motor, so I replaced the impeller, water pump gasket and the thermostat and gasket. The next time I took it out for a weekend on the lake, the motor was noticably quieter, and ran great! Then, the morning that I went to load it up and go home, it would not idle, and ran like total crap. I brought it home, put new plugs in it, and took it out to the river to test it out. Again, ran like crap, would not idle, could not even get it in to gear without it quitting. Brought it back home, pulled the plugs, and I could not get any compression out of the #2 cylinder. I called several marine shops, dealers and mechanics, and sight unseen, they told me it's junk and not worth fixing. Am I really as screwed as they say I am?? Any last resort things I can try to get it running again? I hate to scrap something that could be salvaged.

Any thoughts are much appreciated!!

James"

"James, I will be polite and n

"James, I will be polite and not call it junk, but...

Force is a discontinued, orphaned motor cobbled together with old Chrysler parts/designs.

If you are willing to undertake the rebuild yourself, willing to look around for parts (no dealer network, no longer produced) then it could be a good "project".

It may be something as simple as the rings (bad enough) or a toasted cylinder (then probably not worth rebuilding even at home).

For the cost of fixing this at a shop, if you could find one to work on it, you could purchase a similar vintage in an OMC or a Merc (which sell on the used market for well under a grand) - and are supported, with parts/techs available..."

"Well, first of all, I'd l

"Well, first of all, I'd like to thank you for your expertise, Graham. I very much appreciate it. I think that reality has set in for me, and I have already started looking in the local buyer's guides for a different motor. I have a few leads, we'll see what happens. It's frustrating that it let go after only four times out for me after I bought it. But oh, well. These kinds of things happen. I might keep the Force around, and make a project out of it and keep it as a back up if I'm successful. But, I guess it's like the drivers say in Nascar when they get asked what happened when they have an engine lay down, they say...."She just blow'd up!""

"One of my best buddies has a

"One of my best buddies has a Force 90 - bought it brand new about 20 years ago. He got it cheap (compared to the other brands) knowing that it was a "disposable" engine.

It has ran good all these years, but we have been pretty stringent about keeping care of it annually.

It's not that they are a "bad engine", but now, if they "break" you replace them.

Personally, I would be looking for an OMC in that horsepower (and I own 3 Mercs), they just make a great product.

If you decide to "part out" your motor, you can probably recover most of the costs of the replacement. There is lot's of guys out there trying to keep old Force motors going.

Good luck..."

"Did you have compression in t

"Did you have compression in that cylinder before you did anything to it? Did it sit for a long time before giving you problems? If your a gear head id say its worth pulling apart. You might find its something as simple as a stuck ring - you get it loose, clean it up, put it back together. hopefully you can do this without destroying any gaskets (because those will cost you and are rare)

if your not a gear head you should just go buy a new motor, like everyone says - its a throw away, its not the finest piece of engineering"

"Another last ditch effort &#4

"Another last ditch effort (if your thinking about throwing away the motor this might be for you)

get it running and spray WD40 in the problematic cylinder's carburetor. The WD40 is a lubricant so it won't cause damage like starting fluid or carb cleaner - but it also has additives that help loosen things up. This may help loosen up the rings and get them back against the cylinder wall - if you really want to get aggressive you could try PB blaster or some other rust-buster - if you go that route you should remove the plug and spray it in that way. Make sure you disconnect the ignition to keep it from firing while your doing that. I'd do it more than a few times, remember to spray some oil in there after you are done so you don't 'dry run' the cylinder.

I've also found that with 2 strokes that have been sitting for a long time - after i spray a little bit of wd40 in it to loosen things up, i run gas with twice the oil content in it. I don't do this for very long because it can cause things to foul up, but it will help get all the areas that have gone dry get lubed up.


Also - when its running/cranking, try putting your hand over the carb intake on the bad cylinder, if it feels like its breathing (pushing as much air out as it is in) then it might just be a bad reed valve (im not even sure if your motor has a reed valve - most 2 strokes do) and the tricks to loosen the rings won't help you.

if all else fails - take off the head - check the cylinder wall, if thats scored really bad (usually it will have 45 degree pattern scratches - if its damaged these will be gone and you will see scratches from the piston) then you know that the carburetor/reed valve failed - caused the cylinder to run dry and damaged that section of the engine. If this is the case, depending on how long it was run like that, its likely that all the bearings for that section will also be shot - and if thats the case then you should really start shopping for a new motor.


Good Luck,
-Mark"

"Yes, I am kind of a gear head

"Yes, I am kind of a gear head, I used to be a mechanic for a Toyota Dealership about 8 years ago, but I have honestly never worked on a boat motor before, or a 2 cycle at all before this. I'm hoping that I can learn quickly!

When I bought the boat back in May, I remember the guy telling me that he had bought the boat after it had been sitting for five years in cold storage. He also told me that in the span that he had it, he never touched the motor exept for plugs. I wish this motor had three seperate carbs on it so I could try some of the things that you suggested, but alas, it a single carb motor.

Would it work to spray some WD-40 or PB Blaster in just the #2 spark plug hole? Or would it hurt the other two cylinders to spray it in the carb opening? I know that I can't do much more harm, but I don't want to mess up the remaining good parts if I decide to part it out if it is in fact the worst case scenario. Thanks,
James"

"How did you determine you had

"How did you determine you had not compression?

with a comp gauge or sticking your finger over the plug hole?

id try not to spray PB into the good cylinders - if you want try it, try getting it to the piston through the spark plug hole.

I don't know anything about your particular motor but the reed valve is a one way valve after the carb - before piston intake port. Usually they are between the crankcase and intake runner. The reed valve is basically a little flap of plastic, as the piston goes up it pulls air into the crankcase (because its creating a vacuume) at this point the reed valve opens. As the piston comes down the crankcase becomes pressurized - the reed valve closes - and the intake charge that was in the crankcase is pushed into the combustion chamber.

usually each section of the engine is independant, having its own carb, reed valve, crankcase area, intake and exhaust port - unfortunately i don't know anything about your particular engine.

if you cant verify the reed valve is working i wouldn't go directly to pulling the head off unless you have a spare gasket.

-Mark"

"I first put a finger over eac

"I first put a finger over each spark plug hole just to see if there was any pressure there. The middle one felt like no pressure at all. With a compression tester, the results were #1-90lbs, #2-30lbs, #3-90lbs.

There is some compression on #2, but just from reading other posts on this matter, it's definately not enough to be in the acceptable area.

Hope this helps a little.
James"

"Well, i just got my clymer ma

"Well, i just got my clymer manual in today so i can of more help.

covers 84-99 5-150hp


looking at your engine the reed valve will not cause that low of compression. It will inhibit the flow of fuel/exhaust though. If you need some documentation i may be able to find my scanner and scan the exploded diagrams of the engine it has.

The poor compression could be caused by this valve going bad though, So a bad reed may have been the original cause of the failure - If the valve is bad it will cause a lack of flow of intake charge (oil)

The manual says to treat the engine with 'Quicksilver Power Tune' that is designed to remove engine deposits and free stuck rings. This is called for a deviation of 15psi or higher.

however, from your numbers it sounds like your compression readings indicates a real problem.

I'd try the suggestions i had earlier - soak the piston with PB blaster or WD40. Maybe get yourself a rubber hose that fits snugly into the spark plug hole - put it at TDC and try blowing in it, if you can blow air past the rings thats bad.
If the lubricants don't help pull off the cylinder head and have yourself a look.

Good Luck
-Mark"

"Some parts here ..........

"Some parts here ..........

http://www.outboardparts.com/chrysler/chryslerforce/chryslerforcewelcomepage.htm"

"With that kind of compression

"With that kind of compression, you might be looking at a bad head gasket. Worst case worn or stuck rings or bad piston. You can pick a piston up for about $90 and a gasket set for about $50 or so.

As far as spraying WD 40 into the cylinder, you would be just as well off urinating in there !!! WD 40 is a silicon lubricant period, there are no magic additives. What you need is something called Seafoam or the spray version by Seafoam called Deep Creep. This is used for freeing stuck rings and decarboning outboards and all kinds of engines. A hint for you: spray or squirt some regular engine oil in the low cylinder and then check compression. If it comes up some, then it is ring related. Best bet after that is to pull the head and take a look, then you will know exactly what you have for a problem."

"WD-40 ingredients,
[url=""]

"WD-40 ingredients,
http://en.wikipedia.org/wiki/WD-40

you could always urinate in it though.

One thing he is right about is that with that kind of compression you got problems. I'd give it a ~10% chance that penetrating oil will help. Most likely though you will have to tear it down and re-ring it. There is also a good chance that its not worth the repair - Don't be shocked if this is the case.

Given the work, finding/buying parts, and the reliability of a impartial rebuild - if it needed major engine parts I'd be keeping an eye out for a replacement engine."

"I will try some of the things

"I will try some of the things mentioned (minus the urinating in the engine) and see what happens. If nothing else, I'll part it out. Thanks guys!

James"

"Alright, I sprayed the cylind

"Alright, I sprayed the cylinder with penetrating oil.....I have been rolling it over slowly by hand every few hours. How long should I wait to try running the motor and re-testing compression to see if it is a ring. It seems to be reacting some to it, I have a deposit of very black WD-40 under the lower unit that is running out the center of the prop. But I don't know exactly how long I should wait to let things soak.

James"

"It's not penetrating oil

"It's not penetrating oil that you want to spray in there, although I suppose it won't do any harm. Do yourself a favor and spend $8 on some proper stuff !! Go to NAPA and get some Deep Creep (Seafoam) and follow the directions to decarbon the engine. This stuff is great at unsticking rings. I won't go into what I think about WD-40 (45 years experience).

In lieu of that, you need some honest-to-god oil(either 2 or 4 stroke) to spray into the cylinder before you check the compression. It has to have some viscosity to it. The idea is that it seals the rings and cylinder imperfections. If your compression comes up after the oil, then you know the problem is with the rings or cylinder scuffing. If it doesn't come up, then you are looking at either a head gasket problem or a serious piston or cylinder problem. Do yourself a favor and throw that $2 a can crap away.

Eventually you will need to pull the cylinder head to see what the problem is."

"Well, I took the head off of

"Well, I took the head off of my motor, and found two pistons that are broken around the edges. #2 has 3 bad spots in around the edge, and #3 has two small spots where it is bad. #1 Looks perfect. The good news is, it did not hurt the cylinders at all. No scoring, no scratching. If I can find three pistons and rings, hone out the cylinders and get the gaskets needed, I'll be in business!

Any tips or tricks on this process are welcome! I'm hoping I can make it run again.

James"