Knocks, bangs, and long wait for a tow...

[m4phs]

I have a 2003 SeaRay 220 sundeck with a mercruiser 5.0 MPI. Yesterday, I heard a loud knock once or twice, then it was fine. A few minutes later, several knocks, groans, loss of power, than nothing. The engine would not turn over.

An outside inspection didn't show anything...no oil, no smoke. The prop and outdrive seem fine as well. Waiting for the mechanic to call now, but I'm assuming the worse.

Worst case scenario, relacing the engine, what kind of damage am I looking at?

If I do have to replace it, would it be worth it to upgrade to a 350 with the same alpha I outdrive?

 

[Torque]

What was going on with oil pressure when you were hearing the noise and then just prior to it dying? What RPM were you running? How many hours did you have on it?

Hopefully you don't need a motor. If you do and if I were presented the opportunity to go to a 350 from a 305 I'd do it. Pretty much identical weight, mounting, etc. so you're not changing much with the balance of the boat but you'd have more power. Difference in cost of the engines would probably be negligible. Controls and gages would probably be the same but you'd probably also need a new ECM/ECU which could get spendy. No idea about the Alpha I however in terms of what it can handle. If it's not rated for it I'd probably stick with 305 or upgrade the outdrive to make sure you don't start going through couplers or worse....

 

[Steve S]

My 87 210 Monaco had a 350 Mercruiser (260hp) mated to an Alpha I.... shouldn't be any issue at all.

 

[m4phs]

The last time I had it out, I hit a soft sandbar. I reversed out easily, but kicked up a lot of mud...no rocks, though. Oil pressure and temps were fine, but just before heading back, I heard 2 loud knocks while running at about 3000 rpms. Nothing after that. I took it out a few weeks later (2 days ago) without the kids to check things out, and thats when she died.

Eninge has 400 hours. I just bought the boat in April, and the inspection was fine (compressions were fine, etc).

Temps rose normally to about 160-180 and oil pressure was normal (40-50). Things started when I was running at 3000 rpm, which is the lowest RPM that keeps me on plane, so I wasn't pushing it.

I appreciate the insight on the engine upgrade.

 

[Torque]

Well, the soft grounding and mud churning could be a total coincidence..... but I'm suspicious/optimistic that you may have sucked up mud, killed the seawater impeller, not provided enough cooling to the "exhaust flaps" (or whatever the real technical term is) which caused them to fail, then when backing off the throttle you end up ingesting some water and hydro-locking the motor (this is what the flaps prevent). This is what happened to me with my 230 after I unknowingly planted my outdrive into some mud while launching. Backed the trailer down the ramp, put the outdrive down to fire the motor and warm it up while I loaded some stuff not realizing there was a mud-bar there and I was not pumping water......

Anyhow, primary difference between when it happened to me and the symptoms you described were I immediately noticed the motor was really loud once I got up on plane (no water running through the exhaust) and then almost immediately after that my engine alarm sounded and I'd pegged the temp gauge. Killed the motor and it would not turn over after letting it cool down. After a tow back.... pulled all the plugs, unloaded a can of WD40 into the cylinders, turned it over a ton (all kinds of water shooting out the plug holes), new plugs, new oil, fired off and I was back in business after a new water pump and flappers. Never had a problem since as long as I owned the boat. That was a big block (7.4L) and it held up fine, I've hydro'd a race motor small block after blowing a head gasket and bent a rod with the starter....... So.... even if you hydro'd, you may still be hosed but you at least have a chance at recovery......

I'm a little puzzled though as if that's what happened in your case, I would have expected the temp to be an issue. However, if the bottom end of your motor went....... I would think you would have noticed oil pressure issues.......... Interested to hear what the diagnosis is and best of luck!

 

[JUST PULLIN MY DINGHY]

Did you pull oil dipstick and look for signs of water if you filled a cylinder that would lock the motor up and not show any difference in temp or oil pressure?

 

[ardeprint]

Remove your plugs. If water shoots out you ingested water. The knock could have been a sign of a foreign object (water) in your cylinder(s).

 

[m4phs]

The good news is the engine is fine...but the outdrive is dead. Gears were shreaded. Mechanic wanted to blame the manufacturer (was a non-mercruiser product) or the mech who installed it, but I'm skeptical. Still think driving the prop into mud a 3000+ RPM had to put a lot of stress on the gears...

Thanks again for your input.

 

[ardeprint]

Glad you found the problem. Sorry you found the problem.

 

[JUST PULLIN MY DINGHY]

Bummer but thats better then a motor good luck i agree sudden stop at 3000rpm can't be good .