I have bought a second hand offshore powerboat 34' with two Volvo P 5.7 GS (built 2002, only 100 hrs)and SX drives (built 84). Now I made the maiden voyage and after 20 mins one motor was blown.
Here is the story: when i buy the boat both engines have been completely serviced with new sparkplugs, oilchange, new cables and distributor as well v-belts. also motors have been rebulit with a cooling kit (we are having heavy corrosion due to high saltcontent here in Philippines) to avoid corrosion problems.
When I launched the boat, I started the engines and monitored all functions and they where running nice. I took a tour of 20 mins with max 3500 rpm and engines are fine. Next day we started our first trip and slowly I extended the rpm to 4000. Oilpressure was good, temperature in the lower part. Then after about 20 mins the one engine started to run bad and I immedeately stopped the boat. The engine gave some slight knocking noise and I decided the stop it and return with the other engine.
Back in the port i removed the sparkplugs and found the rear left damaged and covered with aluminium. After removal of the cylinderhead, the worst expectations came true. The piston was heavily damaged and burnt. aluminium is melted and the upper piston rings can be seen.
Now of course I have to repair - however what is my concern WHY this happened, maybe it will happen again after repair.
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Here is the story: when i buy the boat both engines have been completely serviced with new sparkplugs, oilchange, new cables and distributor as well v-belts. also motors have been rebulit with a cooling kit (we are having heavy corrosion due to high saltcontent here in Philippines) to avoid corrosion problems.
When I launched the boat, I started the engines and monitored all functions and they where running nice. I took a tour of 20 mins with max 3500 rpm and engines are fine. Next day we started our first trip and slowly I extended the rpm to 4000. Oilpressure was good, temperature in the lower part. Then after about 20 mins the one engine started to run bad and I immedeately stopped the boat. The engine gave some slight knocking noise and I decided the stop it and return with the other engine.
Back in the port i removed the sparkplugs and found the rear left damaged and covered with aluminium. After removal of the cylinderhead, the worst expectations came true. The piston was heavily damaged and burnt. aluminium is melted and the upper piston rings can be seen.
Now of course I have to repair - however what is my concern WHY this happened, maybe it will happen again after repair.
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