1989 Force 125 won't go above 3000rpm and doesn't have much power....

[Mellinghouse]

I am brand new to boating and just picked up a 1987 18' Bayliner Capri that has a 1989 Force 125. I took it out for the first time today and it would not go above 2500rpm, then died after about 15 min of running. Got it started after letting it sit for 20 minutes, or so, but still wouldn't go above 2500rpm. Doesn't have much power out of the hole. It seems like it's loading up or running rich. I haven't adjusted the fuel mix on the carbs, because I didn't want to mess with them unless I had to. Interestingly, in reverse, the motor seems much more spunky and goes up to 4500rpm. After meandering around for a couple hours, the motor seemed to clean out a bit and run a little smoother, and actually got up to 3200rpm, but no higher.

The previous owner didn't run the boat much, so it hasn't seen much water time for the last 8-10yrs. The motor looks like it's had very little run time. Under the hood it looks nearly new, and the prop doesn't even have a knick on it.

Could this be a carb jet problem? Any info would be greatly appreciated.

 

[pnwboat]

Perform a compression test on all four cylinders, check the fuel pump diaphragm, and also check the water pump impeller.

 

[jerryjerry05]

Do the compression and spark check.
That ok? then clean the carbs and inspect the reeds.
Check the fuel pump and lines.
The inline connectors can leak and suck air.
The increased revs in R I believe it's because of the shape of the prop.
It spins easier backwards.

Running for 15min and dying? could be it's hot and quit running.
Test the alarm system.
Key on, ground the orange lead from the harness tp the block.
The alarm should sound off.
That not working? replace with a car/motorcycle horn.
Just make sure it's wired right.

 

[Mellinghouse]

Thanks for the responses. Okay, checked the compression today, and it's not good, so I stopped there. After the initial test, I did a quick-decarb with the plugs out and carb cleaner, then running it while shooting carb cleaner in the intake to see if it helped at all - it didn't.

#1 - 0psi
#2 - 75psi
#3 - 80psi
#4 - 80psi

I've done a fair amount of mechanicking, mainly on cars, but I've never seen 0psi on a compression test. I don't see much sign of a leaking head gasket. There is a small amount of white residue on the top left of the head near #1, but it doesn't look very serious or fresh.

I'm likely going to pull the head and have a look in the cylinders. I'm guessing a hole in the #1 piston is possibly causing the 0psi? The head looks quite simple to remove, but my question is how difficult is a rebuild on a motor like this? I built a few motors with my old man when I was younger, so it's not completely foreign to me, but I've never worked on an outboard before. Has anyone done one of these before that could give some feedback about complexity? It looks like it can be done while mounted on the boat - is that true?

 

[Jiggz]

You need to take it one step at a time. For now, the next step is to remove the head. This is really simple since it's nothing but a flat head with a gasket and plug holes. Save the head gasket as much as possible for post mortem analysis and if it's in real good shape can also be reused.T hereafter, inspect the pistons and the rings and most importantly the cylinders.

Post your findings and we'll lead you to the next step.

 

[Mellinghouse]

Thank you, you're right. I need to pump the brakes until I get the head off. I"ll be diving into that in the next few days.

I'm struggling to imagine a scenario where I won't be replacing major internal components. Short of rebuild, what could remedy that kind of compression issue?

 

[Jiggz]

Usually, a low compression is caused by a blown head gasket (easy fix) or worse a piston ring that got caught with the ports. Depending how deep the gouge or gouges, it can be repairable DIY or has to be machined.

 

[jerryjerry05]

You can try removing the top cyl. port cover.
It exposes the side of the piston and crown.
That will give you an idea of the damage without removing the head.
The head might be really hard to remove??
Stuck bolts. frozen in place, etc.

 

[Mellinghouse]

So, I pulled the head and the gasket is in really good shape, which is obviously disappointing. The top two pistons have significant scoring/rippling at the uppermost exhaust port. The other two look good. The top two pistons are noticeable more sloppy inside the cylinder, with the top piston being exceptionally bad.

On a positive note, there doesn’t seem to be much, if any, scoring on the cylinders. Certainly no deep gouges, which I really feared with 0psi on the top cylinder.

Seems like rebuild is imminent.

 

[Jiggz]

Next step is to dismount the pistons on #1 cylinder. You can do this by dismounting the top carb, dismount the intake adapter, remove the V-block for the reeds and reaching out for the piston rod bearing caps (make sure you take note of the orientation) and then pulling out the piston. You will need a 12 point 1/4 inch socket to remove the piston rod caps.

Need to make sure you put something to catch any falling parts especially the bearing rollers for the piston rod caps. Once these fall into the motor lower cowling it is almost impossible to retrieve them.

Pics of the cylinder will greatly help in the diagnosis.

 

[Mellinghouse]

I haven’t pulled the #1 piston. Upon further inspection, there seems to be some pretty good scoring in the top two cylinders, especially #1.

I’m hesitant to start pulling pistons one at a time while the power head is still attached, because to me, with all the cylinders exhibiting very low compression, my only option is to have the block bored and rebuild. Am I missing something? At this point, it seems like pulling one piston, knowing the overall compression issues, and the scored cylinders, is a waste of time/energy.

I’ll post a picture of the #1 cylinder. I look forward to your insight.

 

[Mellinghouse]

[No message]

 

[Mellinghouse]

It also looks like something has rattled around inside that cylinder, because the piston has a number of knicks on it.

 

[Jiggz]

The piston and rings are replaceable but the cylinders not quite as easy. So the more important thing to consider is if the scoring in the cylinder(s) is too deep that it will require machining. If such is the case, sometimes you will be better off getting another motor.

 

[Mellinghouse]

Hmm. What does it cost (ballpark) to have the cylinders bored?

 

[jerryjerry05]

The cost varies, I've paid 25-45$ a hole.
You need to find a shop that does the work first.
Lot's of shops aren't setup for that kind of work

 

[Jiggz]

It also looks like something has rattled around inside that cylinder, because the piston has a number of knicks on it.

Most likely it is the broken ring or rings. What you have is very common and usually happens due to lack of lubrication or overheating. Sometimes you'll get lucky and the gouges will be on the ports itself only with very light ones at the compression chamber of the cylinder.

If such is the case, replacing the rings and pistons and a de-glazing honing is all you need to repair it. And to prevent future same problems, chamfer the ports slightly.

 

[Mellinghouse]

Well, I pulled the power head, stripped it completely down, had it bored .040 over. Machinist said it definitely needed to be bored. Now, it's time to order pistons and gaskets. I've seen "rebuild kits" for like $850, but I think I can piece together what I need for quite a bit cheaper.

Any suggestions on places/brands to use, OR stay away from? Looks like Wiseco pistons are about the only way to go. Also, it looks like offshoremarineparts.com has the best prices. Any input is appreciated.

 

[Jiggz]

That looks like a very good price. But make sure you also order the piston pin bearing kit W5216 which you will need for that new wrist pin.

 

[jerryjerry05]

Yes Wiseco is a good choice.

At .040 over your getting into the area where the jets might need to be opened up???
Maybe start a post about re-jetting?


If???? you removed the exhaust chest?
You might want to get the mating surfaces cut down .002-.005
Over time and use the edges get eaten away and cutting them down will
make sure they seal better.

The last block (a 125) I did, I had a B of a time getting it to seal.
Ended up milling it and it worked like a new one.
You might not have a problem but over the years it's been one of the things I found really helped.