😲 2006 9.9 hp Merc.... Hit Rock Full Throttle 😩

[jwsimmons]

Hello,
I was motoring downriver today in an area I'd never been before. I was running the throttle wide open when suddenly we hit a rock pile barely submerged under the surface. It jerked the tiller out of my hand and kicked the motor up 2 notches. There was absolutely no indication it was there other than local knowledge.
After hitting the rock I immediately shut off the motor and looked at the prop. The propeller (aluminum) was banged up a bit but didn't look so bad we couldn't limp home. We pulled over to shore and checked motor oil and it looked normal. Then we decided to putt our way back to the boat ramp. I started the motor and it was making a horrible ticking/knocking noise that was totally abnormal. I continued motoring but never above a 25% throttle. The motor lasted 60 second and the cut out and died. After several extra pulls than usual it started back up and we proceeded a cycle of motoring/dying every 30-60 second on the way back.
If a propeller doesn't "give" from a shear pin or rubber bushing after hitting a rock... what else can happen to a motor? How can hitting a rock cause an apparent engine tick/knock? Why would the motor be dying? It appears as though it may be overheating the way it acts when dying but the motor doesn't feel hot.

Thanks so much,
Jon

p.s. Am I absolutely screwed not having a motor for upcoming spring chinook season in March?!

 

[jwsimmons]

What could happen to a motor internally if hitting a hard object @ full throttle? It doesn't appear as though there was a shear pin or rubber bushing on the prop that gave way on impact. The motor doesn't shake or vibrate violently as if a shaft is bent. Just a smooth ticking noise which appears to be coming from the upper section of the motor... not the lower unit near point of impact.

 

[jimmbo]

An engine running at WOT, basically has a Gyroscope spinning at high rpm at the top. Like all Gyroscopes it will has enertia and does not like to be subjected to violent changes in position, or speed. Flywheel keys have been known to shear. Knocking sounds are never good. Best advice would be to take the motor to the dealer and have them check it over. Do you have all risk insurance on the boat/motor?

 

[Scott Danforth]

could be flywheel key like jimmbo mentioned, could be something internal if the motor slowly dies, it could be fuel, you could have knocked something loose in the carb. if it just dies, it could be timing is off far enough due to a sheared key

 

[racerone]

2 stroke or 4 stroke ?---Model #

 

[jwsimmons]

Yikes this doesn't sound good and no risk insurance. It's a 4 stroke. Serial #: OR119341
The whole reason I'm on here is to avoid going to the dealer. I made the mistake of having them do a routine upper and lower fluids and impeller change last year because I figured it wouldn't hurt to have professionals look over the motor.... $550 later! The motor can't be worth more than $1000 in fully functioning condition. I will have a hard time paying for a major repair at a dealer if it's as serious a sheared flywheel.

 

[jwsimmons]

Is there a way I can post a video of the motor running and dying on here or do people usually post on Youtube and then provide a link here?

 

[racerone]

Dealer service on 4 strokes is big $$$ ------They run nice when they run.-----Check the belt timing on this thing as it may have slipped !!-----Sounds like major decision time for a replacement motor to me.

 

[jwsimmons]

I've got a seloc manual coming from the library right now. I'll look onto the flywheel key and timing. Those both seem plausible to me givin the type of impact.
Any other ideas of what it could be? Of course I'll start with simple things like prop, prop shaft, general lower unit inspections, etc. before I get involved so much as to pulling the flywheel or adjusting timing! Both those sound easier than tearing into the case and inspecting positions, etc. though!
I've pulled a flywheel once before on an old 2 stroke motor (didn't fix it) but never messed with timing on anything but my Toyota Corolla. That was pretty easy.

 

[Sea Rider]

Does motor makes strange noises when not geared, say running at fast idle or when geared running at fast idle with propulsion? Have seen 2 cases where OB's running full wot were suddenly stopped when prop hit sand beds, rocks even caught a fishing net, OB began missing with 0 propulsion, but that scenario was with 2 strokes OB. What happened ? the upper drive shaft splines broke off, shaved even achieving 0 propulsion..

Flywheel key is usually SS will doubt is bent or jumped off from crank's groove. What might have happened is that cam's driving/timing belt slipped a teeth or two from crank shaft pulley position, at restarts engine runs out of correct synch, even having a piston banging against head valve if being a 4 strokes OB. To check that out, remove both spark plugs, at neutral pull starter cord gently and check if those strange sounds are heard, if so, something is wrong internally.

Check upper drive shaft splines and timing belt synch to start with, it's a simple check and or adjustment if needed.

On first case, will need to pull lower leg down to check that, to check flywheel key need a flywheel puller, to check timing belt just have a look and know factory timing positions. Just for the record, report if any of 3 mentioned cases were the culprit.

Happy Boating

 

[jwsimmons]

Okay, the more I hear people talk about it the more the timing theory is sounding consistent with the symptoms.
It makes the ticking noise whether it's in neutral, forward, or reverse. It also seems to have a normal level of propulsion per RPM, at least at lower RPM's. I haven't given it more than 50% throttle just because I can't imagine it would be good for it.
Do these motor's have a timing belt or chain?

 

[racerone]

The timing belt should be visible at the top of the motor !!----Check belt timing before spending much more time guessing .----Check belt timing before spending another $ on this motor !

 

[Sea Rider]

It's generally a black thick rubber belt with lots of teeth driving 2 horizontal pulleys. Once had this timing issue in which 2 teeth were pulled off from belt, engine went out of synch and engine stopped suddenly, luckily no piston head banged any valve head due to engine having a high cylinder head..

Happy Boating

 

[QBhoy]

Is there still cooling water from tell tale ?

 

[jwsimmons]

Yeah a nice steady stream is still coming out. The engine doesn't seem overly warm.

 

[Alumarine]

Yeah a nice steady stream is still coming out. The engine doesn't seem overly warm.

When you say the engine doesn't seem overly warm are you checking the temperature on the block or the outer cowling?

 

[jwsimmons]

Both. Checked outside and behind engine near exhaust and water stream as well as block with cowling off.

 

[Sea Rider]

If still with an internal metal sound when flywheel is tunred slowly with starter rope, better cheking with both spark plugs removed, don't continue using that OB or will end screwing it much worse than it's now. The remedy is going to be way more expensive than the disease ...

As long as OB runs idle, fast idle or with more throttle water pump will keep pumping and water indicator (peeing port) peeing accordingly.

Happy Boating

 

[jimmbo]

Is there a way I can post a video of the motor running and dying on here or do people usually post on Youtube and then provide a link here?

Youtube and link are how it seems to be done
A video may offer more clues.

 

[Sea Rider]

Consulted 3 high skilled 4 strokes OB techs about this strange banging like internal sound, all agreed that a timing belt slip due to lower leg high impact is to have in consideration, this same issue has happened to them some times before. A video won't bring anything new as you can't visually check the OB interior...

Happy Boating