1987 Force 125 Question.

[wan2live]

Hi,

I just bought a 87 Bayliner Capri /w a Force 125 OB.

I did a Compression check today (not before buying the boat) it was only 500.00 for everything. The top 2 Cylinders have great compression 110 but the bottom 2 are very low in the 30's 60's, when I pulled the plugs I noticed that there was a rust color on the bottom, is this an indication that the pisons are stuck? the boat was sitting for a year but I am thinking maybe a bad head gasket? can I spay a lubricant in the spark plug hole?

I can get some sea foam but will that possibly correct this?

Thanks in advance.

 

[john from md]

Re: 1987 Force 125 Question.

Normally carbonized rings do not usually give you numbers in the low thirties. Since you don't know the history of the engine, it would be smart to pull the head and the port covers to get a good look at the piston domes, skirts and head. No sense wasting a can of Seafoam if you have serious damage in the engine.

John

 

[wan2live]

Re: 1987 Force 125 Question.

Ok thanks for the response I will take a look, I'm thinking new rings etc but will have to get a look see.

 

[john from md]

Re: 1987 Force 125 Question.

If you want to get a better look at the under side of the pistons, there are about 10 bolts on the reed valve plate, behind the carbs, that will allow you to see everything.

John

 

[mnmike3]

Re: 1987 Force 125 Question.

man this seems to be a common issue with these older force motors. i'm in the process of assessing the damage to an 86 125 i just picked up this week.

 

[john from md]

Re: 1987 Force 125 Question.

That is because the 70- 140HP Force line was mostly put on boats made for skiing. In this application, the engine was run at WOT most of the time and many owners didn't maintain them too well.

They did things like, run a tank till empty at WOT, never changed a water pump, used too small a prop pitch and constantly overreved the engine, failed to add oil to the fuel, failed to respond to the overheat warninng.

It is a wonder that they are still operating at all!.

I can tell you this, if they are maintained properly, they are bulletproof. Mine is 25 years old, still holds 150 psi compression and I get 43 MPH out of my Bayliner Capri at WOT.

Treat them right and they will last a long long time.

John

 

[mnmike3]

Re: 1987 Force 125 Question.

"I can tell you this, if they are maintained properly, they are bulletproof. Mine is 25 years old, still holds 150 psi compression and I get 43 MPH out of my Bayliner Capri at WOT.

Treat them right and they will last a long long time."

thats what I want to hear

 

[wan2live]

Re: 1987 Force 125 Question.

Thanks for the additional information.

I purchased the online Seloc manual which does not really have as much as a book would but it does give me part numbers and exploded views.

I'll report back on my progress and findings, I would much rather go ahead and replace the head gasket and rings then mess around and it is still fairly early in the season, does this sound like a good approach?

What are the recomended parts for the replacement of the head gasket and Rings?

Head Gasket, I see an A and a B on the parts list with the same OEM number, do I require 2?

Piston Rings x 4

Anything else?

Thanks in advance

 

[john from md]

Re: 1987 Force 125 Question.

Don't rely on the Seloc manual for a parts breakdown. Go to mercruiser.com or franzmarine.com or dougrussel.com and look at their schematics. You can also compare prices as well.

John

 

[wan2live]

Re: 1987 Force 125 Question. (Update)

Re: 1987 Force 125 Question. (Update)

Hi,

So I took theplunge today and took the head cover off, I found that I had a blown head gasket, who knew?

I looked at the pistons and they look to be in good condition, the cylinder walls are in good condition as well, thank goodness for that.

I am attaching some photos of the gasket and the cylinder cover and cylinders.

 

[john from md]

Re: 1987 Force 125 Question.

Clean it up with a rotary scotch brite wheel and put 'er back together. After you get it running, you need to do a good decarb maybe two of them. That engine is loaded with carbon.

John

 

[wan2live]

Re: 1987 Force 125 Question.

Thanks John. I just ordered a new head gasket so I have a few days to get it nice and shiny.

I will report back once I get it back together and running.

Thank you again.

 

[wan2live]

Re: 1987 Force 125 Question.

Hi all...

Just an update to this thread. I posted on someone elses topic becausethey had a similar problem so maybe this wil help them.

As you know I ordered the new head gasket last week, it arrived yesterday so I went to work putting the head cover back on on torqueing to spec, well as always there is always 1 bolt, screw or nut that causes you pain, one of the bolts that holds the breaker bracket to the cover had stripped threads in the housing "yay" so I went to napa today and bought a heli-Coil kit and repared the bad insert.

I bolted everything back down and started up the 125, before hand I did a compression test and I still had low pressure in #3 "sigh" BUT after getting the engine started and a little decarb the compression came up = to #1 #2 and #4 so I now have a solid running 125 from what I can tell using a bucket test.

When I started it up it was stuck in WOT even though the shifter was in Neutral and centered, I removed the screw with the plastic roller so I could get it to just idle which it did well.

I am unable to take it to the lake right now because the Neutral throttle cable seems to be siezed, I noticed small cracks in the outer cover so I used some PB Blaster to try and free it up and my neighbor who is a avid boater had some kind of spray he used on his cable to free it up. It looks like I have yet another project to work out, I ended up losing the screw that holds the cable in place :-( but I am going to Lanier Marine tomorrow to looks for some back to back seats so maybe I can pick one up there.



Thank you very much for all the help!

 

[wan2live]

Re: 1987 Force 125 Fixed

Re: 1987 Force 125 Fixed

I had a chance to take the boat out on the lake today and make some adjustments.

@ WOT with a good tilt I maxed at 40mph according to the boat and 36 on my gps, today was a decarb / adjustment day and once what was left of the old fuel the force started to run a little better but top speed right now is 40 @ wot. I am sureonce I change the plugs this week and run the rest of the fresh fuel through t will run even better.

This post can be closed as the engine is solid without any failure after the fixes that were dne previously.

Thanks!

 

[john from md]

Re: 1987 Force 125 Question.

Love those fancy gages!

Do another decarb and let it sit for a day or even all week. Then take it out and run the hell out of it. That should bring your compression up even more.

Nice job.

John

 

[wan2live]

Re: 1987 Force 125 Question.

Love those fancy gages!

Do another decarb and let it sit for a day or even all week. Then take it out and run the hell out of it. That should bring your compression up even more.

Nice job.

John

Thanks John, I will do another decarb, replace the plugs and the fuel filter, I also need to get a water separator because there is not one installed, I will report back if I am able to get back out next weekend.

 

[Frank Acampora]

Re: 1987 Force 125 Question.

Just r4member to re-torque the head bolts to 225 inch pounds after heating the engine. They will come up about 1/4 turn because the new gasket takes a set. Old re-used gaskets are fully compressed and do not need to be re-torqued after heating.

 

[wan2live]

Re: 1987 Force 125 Question.

Just r4member to re-torque the head bolts to 225 inch pounds after heating the engine. They will come up about 1/4 turn because the new gasket takes a set. Old re-used gaskets are fully compressed and do not need to be re-torqued after heating.

Thanks for the info Frank I will re torque tomorrow.