150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

We were out on the lake today for most of the day and everything was great. We have a 1989 bayliner fish and ski 19 footer. it ran at 2200 rpm's 24 mph for most of the day. not a hiccup. i dont typically run wot. At the end of the day we went to the dock and i shut it of and went to get the truck and backed in in. Got in the boat and it wouldnt start. I ended up just pulling it down the 150 foot dock and cranked on the trailer. Got home and started checking things and found that #3 was only 50# of compression. the other five were right at 140. I pulled the head and found that there was a bend on the piston and well just look at the pics cause i dont know the lingo. I dont think the it scratched the jug to bad. it has very light damage. But i think the piston is damaged. One pic is #3 piston and the other are the plugs in order. What is my best plan of attack here? Thanks ahead for any advice.

Re: 150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

Yup looks like the middle piston took a crap.
The rings possibly got stuck from carbon.

Do this(looking for a reason it failed?)turn the air screw on the middle carb in,counting the turns till it bottoms out.
Then back to where it was.
Post the results.
Then the same on the other 2 carbs.Post these results too.
The scoring on the walls looks like it needs to be bored and a new piston installed.
Unfortunatly these things can go bad at any speed.
I baby mine and almost never go past 4200 but once in a while I open it up and blow the carbon out???

Re: 150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

Bad news: The piston has broken a top ring. These pistons have a tendency to do that. Good news: The piston can be replaced without disassembling the engine. Remove thecenter carb and manifold servicing that piston. Using a 12 point 1/4 inch socket, remove the rod big end and push out the piston and rod. Account for all 16 rollers. Retrieve the rod big end cap and note which way it fits on the rod. It only attaches one way.

Lightly hone the cylinder with a Sears 3 stone hone (or other if you can find one) and insert a new piston with the old rod. Through the front opening insert the cages and rollers. This takes patience. Attach the rod big end cap and torque the cap screws to 190 inch pounds.

Replace carb and manifold-- most likely you will need new gaskets as they are glued at the factory.

Re: 150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

The good news is everbody got home safely and you have a boat to work on. Not every person can say that.

Re: 150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

Alright well that doesnt sound too bad. I will go buy what i need to do the job and get to work. This will take me a few days so i will post results when i get either done or stumped. Thanks guys much appreciated.

Re: 150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

How deep are the grooves in the cylinder wall?

Re: 150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

Ok I have taken everything apart and honed the cylinder walls. It all appears fine me but i would like some input on the pictures from you exp. guys if you dont mind. The rings were definately broken i found small peices behing the reed valve. There are a few little dings all the lower part of the wall that im not sure about. I have a few questions too.

Do i need to put something back on the cylinder walls? coating of something perhaps or not necessary

Does a new piston come wth the arm attached if not how do i get the other one off?

When ordering a new piston do i just get standard for the motor?

And the adjustment on the carbs were all at 1 1/2 turns out so should i turn the middle one out another 1/4 turn or more?

Thanks again

Re: 150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

It was not a lean run due to carb problems that caused the broken rings. Those stock pistons with the semi-keystone top ring are prone to breaking them for no particular reason So, leave the carbs set where they were.

That is a 3.375 bore engine. look at the tops of the other pistons. If there are no marks in them then it is a good bet that they are not oversized. To be certain though, borrow a caliper and measure the bore. It should be exactly 3.375 or 3 3/8 inches. If so, order a standard sized piston.

The arm is called a connecting rod. it is attached to the piston by the wrist pin. The wrist pin is pressed into the two keepers on eother side of the needles. You need to press out the existing wrist pin. If you buy a Wiseco piston, it will come with a new wrist pin and rings.You will need to buy a bearing kit also. This is to say that if you buy a Wiseco piston, it will not matter if you damage the keepers or needle bearings. Thus, you can hammer out the wrisrt pin.

Your photos show a couple of nicks at the exhaust ports and there are still a couple of small imperfections in the cylinder wall BUT:They do not look to bad and you will most likely get adequate compression and very close to normal performance. It is not necessary to put anything on the cylinder walls except a coating of TWC-3 oil for assembly. Coat the rings and piston skirt too.

One hint: If you should need to hone a cylinder again, run the hone slowly and move it in and out at a rate so that the hone marks in the cylinder cross at about a 60 degree angle. This aids in "seating" the new rings.

Before you assemble the piston into the block, test fit the rod cap on the end. It only goes one way and if installed incorrectly, will result in even more engine damage. Use grease to retain the rollers and cages. After all are in, replace the cap and just snug it. Test the ground flats on the rod to make sure thay are even and turn the engine a couple of times by hand. Then, tighten the rod cap bolts to 190 INCH pounds.

The rod is a very close fit between the crank cheeks and if off center or cocked slightly it simply will not go. Here is where it may fight you and you will need to be patient. Make sure it is perfectly horizontal and using a long rod, wiggle it back and forth to center it between the crank cheeks.

Re: 150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

Thanks for the info. I will order it and get rolling but im having a problem finding a piston. I called both of my boat dealers in the area and they said its no longer available. One place told me that they had a scrap engine that they would sell me for $200 and i could pull one out of it. I dont know what to do. Should i just get a wiseco or is there somewhere that has the original piston for my motor?

Re: 150 force I THINK SOMETHING IS BROKE please give me good news i have pics.

http://www.marineparts.com/mpf/mpf774.aspx


better measure your bore.
89-90 models should have 3.312" bore.