Optimax 200 M2, hole in powerhead

[Oka]

I have only had my seadoo utopia 185 (2002) for a short time, on the weekend we were out in the ocean it was very calm so i decided to open it up and was doing 5800rpm at approx 50mph, thing were going great until the engine changed its tune and i had no throttle.

It turned out that a hole had been blown in the side of powerhead just behind a linkage on the throttle. I am now left with not nowing what to do, would be interested to hear if anyone else had similar problems with the optimax. I had now warning alarms or lights come on.

Terry

South Australia

 

[WAJetboating]

It turned out that a hole had been blown in the side of powerhead just behind a linkage on the throttle.

My first guess would be that you lost oil injection. It's a classic self-destruction scenario for 2-stroke engines. Did (and do) you have oil in the external and on-engine oil tanks? Any hoses pinched or obstructed?

You could remove the oil pump and see if the drive shaft coming out of the engine can be rotated by hand. If so, you've probably stripped the oil drive gear on the driveshaft.

This is repairable, since the basic engine is common to countless outboard engines Mercury has built for many years. Any certified Merc shop will be able to work on it. You're going to need a new engine block and those aren't cheap, but it's very likely the rest of the components can be saved (except perhaps the piston in the blown cylinder).

No matter what else, make certain you diagnose, understand, and FIX the problem that caused this or you'll simply repeat the experience with your repaired engine.

 

[Oka]

From what I can see the oil injections is still operating ok. At first I did not realise what had happend, I lost the throttle operation and the motor was still running but could hear something wasn't right, I was about 5km ( 3mile) from the boat ramp so slowly nursed it back at about 10mph having a mate operate the throttle by hand on the side of motor, took about half hour. After retreving boat from water and removing engine covers it was discovered there was a hole in block just above piston, piston looked ok.

I have resently purchased the boat at auction from a dealer how went bankrupt so I dont know the history of boat, have only used it a hand full of times and this was the first time I have taken revs past 4000 so very disapionting.

Im hoping to be able to pick up another block and rebuild but as you said this wont be cheap.

Cheers Terry

 

[WAJetboating]

I have resently purchased the boat at auction from a dealer how went bankrupt so I dont know the history of boat, have only used it a hand full of times and this was the first time I have taken revs past 4000 so very disapionting.

Your engine should redline around 6000 RPM's so being above 4000 should not have been an issue. There is some tribal lore around that says sustained operation above 5000 isn't recommended, but I've run my 240EFI (related but not identical engine) at 6000/WOT for longer periods of time without incident. Then again, I know the history of my engine very well and do my own maintenance so I know everything is in top shape.

Can you see if there is scoring on the walls of the lost cylinder? Are the rings still in the piston? If you didn't lose oil injection and the engine continued to run for quite a while after the event, it sounds like the problem is local to that one cylinder and the cause must be found there.

There are several companies that rebuild/reman those engine blocks. The ones I've heard of are stateside, which might make shipping a pain, but they ARE out there. Do some Google searches. I've searched before and posted company names here, so search this site too.

Good luck and report back!

 

[RFoster130]

That really sucks. Its gonna be an expensive fix.