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The parents in law gave me a jet boat, it hasn't been started in 5 years. The boat resided in NH on a trailer on their yard for 5 years, so it has seen freezing temperatures frequently. From what I understand, 6 years ago the boat ran fine at the end of the season it was winterize. At the beginning of the following season, the owner was unable to start it and just gave up.

It is specifically a 1991 or 1992 Boston Whaler Rage.

The manual can be found here: Boston Whaler Rage Manual.

The boat has a Yamaha two stroke engine in it ( model number : j650c ).

The engine has been submerged in water up to the drive train. When I went to change the spark plugs and found that one of them was loose. There was about 3oz of water out of the chamber under the spark plug that I sucked out. I tried moving the driveshaft with my hands but I am unable.

My next plans are to spray 'PB Blaster' in the spark plug holes, probably a couple times over the course of a week, and then use a wrench to try and get the driveshaft spinning.

Is this a reasonable thing to do?

Is there anything else I should lube to try and get the driveshaft spinning?

Should I be more concerned with other aspects of the boat?

The driveshaft should be able to move by hand, correct?

I understand the impeller may be frozen as well, should I detach that from the engine before trying to spin the driveshaft?

These motors want the oil mixed right into the gasoline for the engine, is there any other place where I should be changing oil?

Any tips or advice will be much appreciated!

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  • Did they mention any issues with the boat before they let it set all that time? I'm not familiar with a jet boat, but what happens to the "jet" part after sitting motionless in water for that long? Maybe inspect everything and make sure its even worth trying to get the engine to turn.
    – JPhi1618
    Commented May 6, 2016 at 14:48
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    Does the engine look like this one? Because that's only $500.
    – JPhi1618
    Commented May 6, 2016 at 14:55
  • That seems to be the engine, and I will absolutely save the link as a contingency. Thanks.
    – Calvin
    Commented May 6, 2016 at 15:33
  • Awesome, and if nothing else it adds information to the question. There are some motorcycle guys around that have probably tried to get a 2-cycle going again. Great detail in the question.
    – JPhi1618
    Commented May 6, 2016 at 15:35

4 Answers 4

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Water in the cylinder usually means water in the crankcase on a two stroke

Pulling water out of the cylinder doesn't mean you pulled out all the water. Two stroke engines use ports on the side of the cylinder rather than valves at the top of a cylinder (4-Stroke). The ports run down the outside of the cylinder wall into the crankcase which means there is a high probability that there is water in your crankcase.

Results of Water in Crankcase

  • Rusted main crankshaft bearings

  • Rusted connecting rod bearings

  • Rusted rings seized to the cylinder wall

Remediation

You can take the cylinder head off of the top of the motor. There is nothing technically difficult regarding removal and re-assembly. There are no valves or machinery in it, just take off the bolts and remove the head.

Now will be able to see the top of the piston. You can knock the top of the piston with a hammer and screwdriver.

Put the handle side of the screwdriver against the top of the piston and hit the screwdriver shaft with the hammer. If you can't get the piston to move, it's probably seized.

@moab has good advice. Disassemble the motor and inspect it for rust/debris. I suspect bad news and a complete seizure at the crank as well as the pistons being seized to the cylinder wall.

Good luck! You have quite a project on your hands if you've never rebuilt a two stroke.

EDIT:

Here is animation to give you a visual of how water can get into the crankcase of a two-stroke engine.

enter image description here

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  • I'd suggest using a scrap of wood instead of a screwdriver to free the piston. No sense taking a chance of damaging either the screwdriver or the hammer (and possibly injuring yourself).
    – TMN
    Commented May 6, 2016 at 18:44
  • Yup, that will work as well. good idea.
    – DucatiKiller
    Commented May 6, 2016 at 19:19
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Water in the cylinder?

The engine is in bad shape from improper storage. Even if you get it freed up there will be rust on the cylinder walls and piston rings, which will cause more damage if you manage to get it running or spinning over with the starter. The best solution is removal and complete disassembly and inspection of the engine. Make a decision to rebuild or replace after tear down of the engine.

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At best, "persuading" the engine to turn over will result in damage when it is started (because of rusty bearings, etc.). You might not even get that far, and you'll damage a piston or twist the crank while trying to free it off.

Dismantling a two-stroke engine is very simple. Then inspect everything. With luck, you can put it back together with new bearings, seals and piston rings, and you'll have a reliable engine. And if you're not lucky, at least you haven't bodged it, gone to sea and then broken down.

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Check your manual. Pages 40 to 46. There is a page that refer to diagnosis of starting issues. There is also a schematic. It mentions loose connections etc. Check all your connections and examine all the wiring for signs of corrosion and arcing (melted insulation etc). It also mentions what to do about induced water damage.

I think this could be a duplicate post concerning the same boat regarding an electrical issue....then I've answered both questions.

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