Force 125 Loss of Compression

[ambrowns]

Yesterday, we took the boat out and found that we couldn't get on plane at all. Looking back, I think it has been slowly loosing power over time but I didn't realise it at the time. Afterwards, we checked the compression and it was 60, 0, 95, 115. Today, we took the head off to look in there and see what was going on. I have never looked at the pistons or cylinder walls on any engine before so I guess I'm not sure exactly what I'm looking for. I decided that I would take some pictures and post on here and see what others think.



It looks like all the cylinder walls do not have any pitting or scoring. On the #2 cylinder (the one with 0 compression), there is something above the surface of the cylinder wall that almost looks like something was repaired. Each of the pistons look like they are a bit damaged on the sides. I need to resize the pic of the head gasket but from what I can tell it looks fine with no cracks or anything. What does everybody think and what should I do next?

Aaron

 

[redneckboater]

Re: Force 125 Loss of Compression

Wow... yeah you definitely have a blown power head. It will need to be bored over and new pistons and rings on all cylinders. The damage you see on the top of the pistons is broken piston ring lands where the rings have caught the exhaust ports and pulled thru the top of the piston.

I say rebuild if you are able and have the time. Most repair shops will charge you way more than what that motor is worth to do it. So your best options are either repower or rebuild yourself.

Hope this helps.

 

[pnwboat]

Re: Force 125 Loss of Compression

The chips on the outer edge of the pistons are not supposed to be there. Pieces of the pistons are gone. Your pistons are damaged. The third piston shows signs of excessive heat and looks like it has started to melt. The spot that looks like a repair is actually a piece of the aluminum piston that has stuck to the cylinder wall. Something probably went wrong either with the fuel mixture or ignition timing to cause this damage. Either take the block apart and bore the cylinders and install new pistons and rings or look for a replacement power head. You also need to determine what caused the problem ( fuel mixture, ignition timing, bad gas etc) otherwise it will happen again.