Force 125 - Low compression in one cyl. Rebuild?

[volkey]

First post. Hi.

Have a 1986 Bayliner Bass boat with a 125 Force. Took it to my local shop to have the motor serviced for the first time under my ownership.

Just got a phone call from the shop. They did a compression test before doing any other service, and called me with the results.

Top to bottom compression on the cyls: 140, 128, 128, 20(!)

There was visible scoring of cyls 2 and 3 but they didn't pull apart the motor to the point where they could inspect the bottom cylinder.

His recommendation to me was to look into a replacement motor as Force parts are harder to come by now (is this true?). He was going to let me know what he was able to find out as far as sourcing a used outboard for me in the next few days, so I figured I'd poke around the 'net and see what I could find out about possibly rebuilding the existing motor.

Would it be more cost efficient to rebuild or replace?

 

[Justinde]

Re: Force 125 - Low compression in one cyl. Rebuild?

Hi Volkey

Welcome to iboats. If you have the inclination, and a good manual ( Clymers workshop manual), and help from this site, you will get away with a rebuild yourself. When I first started ( a noob), I had no idea, but now there is nothing I wouldn't do to my Force 125 myself. Parts are readily available, look below

http://www.ebay.com.au/itm/New-Pist...at_Parts_Accessories_Gear&hash=item41435a350c

http://www.ebay.com.au/itm/FORCE-OU...at_Parts_Accessories_Gear&hash=item5d28e4655c

http://www.ebay.com.au/itm/New-Fuel...at_Parts_Accessories_Gear&hash=item41541b36ca

http://www.ebay.com.au/itm/Force-Ou...at_Parts_Accessories_Gear&hash=item5d2d122dfa

http://www.ebay.com.au/itm/Chrysler...at_Parts_Accessories_Gear&hash=item53e6b649c8

These are the parts I reckon you may need- except the conrod- that depends on the condition of yours. Ignore the shipping costs- I live in Sydney, Australia and the links are ebay.com.au links- do your own search or ask these sellers what shipping to you would cost. All up, it looks like about $450 in parts, including the pistons ( x4), new waterpump, new fuel pump ( assuming yours is ****) and a gasket set complete. Do your own labour, and your set.

Depends on what model/size engine your marine tech wants to replace it with, and how much he wants to charge. Force engines are dependable, and parts are easy to come by ( except l drives). Mine still has some issues I am ironing out, but other than that, I'd go with a DIY rebuild

 

[volkey]

Re: Force 125 - Low compression in one cyl. Rebuild?

Being that the compression is SO much lower, that's likely some type of physical damage like a ring broken or a piston needing to be replaced?

 

[Justinde]

Re: Force 125 - Low compression in one cyl. Rebuild?

Probably- but the pistons I gave you are oversize by 10 thou - allowing for a rebore/hone if required. - but pistons are available in larger sizes, up to 30 thou i think.

 

[jerryjerry05]

Re: Force 125 - Low compression in one cyl. Rebuild?

Where are you located(profile)? Craigslist has lots of outboards for sale.My area a guy was selling 2/125's and a parts motor for $500.All supposed to run.
It might be easier to swap motors than rebuild if your not comfy rebuilding.
The pistons can be fun to replace on the rods.
There was a reason it went south,figure that out first.Jerry

 

[shadow7g]

Re: Force 125 - Low compression in one cyl. Rebuild?

How reputable is this shop? If it was me. I would bring it home and check the compression for myself OR make them show me. They could just be getting out of working on the force and trying to sell you a new engine. However, its your choice. I personally dont trust shops or dealerships.

 

[volkey]

Re: Force 125 - Low compression in one cyl. Rebuild?

How reputable is this shop? If it was me. I would bring it home and check the compression for myself OR make them show me. They could just be getting out of working on the force and trying to sell you a new engine. However, its your choice. I personally dont trust shops or dealerships.

I know the owner personally, and knew him before I had a boat OR knew he owned it.

He's the one who told me about the cylinder, because he didn't want to do any other service work and cost me money before telling me the motor had issues.

 

[volkey]

Re: Force 125 - Low compression in one cyl. Rebuild?

Where are you located(profile)? Craigslist has lots of outboards for sale.My area a guy was selling 2/125's and a parts motor for $500.All supposed to run.
It might be easier to swap motors than rebuild if your not comfy rebuilding.
The pistons can be fun to replace on the rods.
There was a reason it went south,figure that out first.Jerry

I'm in the SF Bay Area.

Craigslist isn't turning up much for me so far.

 

[volkey]

Re: Force 125 - Low compression in one cyl. Rebuild?

Update, as I've finally had time to pop the head off and see what's what.

I don't see anything much different in cyl #4 than the others.

There is some white residue that I can't identify on Cyl 4 (the one with 20 compression) and also some on 2 and 3, but not as much. I don't see any broken bits and pieces that would make me think a piston ring has been broken up or anything.

Head gasket is intact, so I can rule out that as well.

Suggestions on how I should proceed here?

 

[volkey]

Re: Force 125 - Low compression in one cyl. Rebuild?

 

[jerryjerry05]

Re: Force 125 - Low compression in one cyl. Rebuild?

The bottom cyl.is shot.The piston has melted and deposited aluminum in the grooves.
The ring might not be broken just stuck.
Gonna need a new piston and a bore out to .010 over.J

 

[Frank Acampora]

Re: Force 125 - Low compression in one cyl. Rebuild?

Well, this is one time where I may have a minor disagreement with Jerry: Yes, the bottom cylinder does have aluminum rub-off and yes it SHOULD?COULD be rebored. However, depending upon the actual damage and your circumstances, it may not necessarily absolutely need to be done.

If money is an issue or you just can't/don't want to do the work: The aluminum can be scraped off the cylinder and then it can be honed. Piston should be popped out to check the rings but this can be done through the reed opening without disassembling the engine. The engine won't run 100% but it will run satisfactorily.

In any case, no matter what you do, it will end up costing way less than another engine If you do most of the work yourself (unless you buy a cheap piece of cr** which will let you down anyway) If you have a mechanic do it, it will cost just as much as buying a used engine of similar size.

But, as stated above, parts are available and the engines are easy to work on, requiring almost nothing more than good hand tools.

So, now you know your options and can make a better decision.

 

[volkey]

Re: Force 125 - Low compression in one cyl. Rebuild?

Thanks for the input. I think for now I am going to try and pull the piston, hone the cylinder, and evaluate the parts when I get them removed.

If it's a stuck ring, and not broken, does that mean it's reusable? Stuck meaning it's literally stuck in the ring groove and unable to move at all?

 

[Frank Acampora]

Re: Force 125 - Low compression in one cyl. Rebuild?

With the amount of aluminum rub-off in the cylinder, the ring lands will be damaged and almost certainly you will break the ring(s) in trying to get them out. It is do-able, I have done it, but it took hours of frustrating time to free one ring. Stuck means stuck as in not moveable--probably a combination of carbon and aluminum.

If the ring does not have grooves in it and if you don't break it, then yes, it is probably reusable. Practically though, buying a new set is better and they are not too expensive. Just be certain you get the correct rings for your engine.

Post a couple of photos of the piston when you get it out of the block. When you remove it, COUNT all 16 rollers on the big end of the rod and be sure you have retrieved all of them from the block .

 

[volkey]

Re: Force 125 - Low compression in one cyl. Rebuild?

Will do, thanks.

So I can just hone the cylinder and go with a stock sized piston and rings -- what's the hot source for the parts nowadays? Is there a favorite website somewhere?

 

[volkey]

Re: Force 125 - Low compression in one cyl. Rebuild?

I have a somewhat sad update.

While I was trailering it today, the bar that locks the motor tilted up somehow shook itself loose, causing the motor to be fully trimmed down while driving.

As expected, a divot in the road snapped off the fin of the lower unit.

RIP Force 125 motor.