Super Genius strikes again-305 Mercruiser Alpha one- Ran perfect-Now toast

[7362]

Well, Finallly got the boat all tweaked up. My new Rochester Quadrajet was performing well. The other two barrels opened up for the first time and I now had full power available.
(I had posted a thread on no acceleration over 3000 rpm, but the as it turns out I mistakenly received a 5.7 L carb for my 5.0L 305 cu in. In any case this solved the accel problem and all was well,
but read on...)

Here is where the story goes bad. Went out the inlet to the ocean here in Pompano Beach FL. Opened the Wellcraft Eclipse 21 foot up, and before I knew it we were about going about 45-47 mph.
Throttle flat. Made a few runs at full speed. THen heading in, bang boom, and a bunch of awful sounds coming from engine. End of a good day, hello to an expensive day.
I love boating. IN any case, after a $500.00 tour back to the ramp courtesy of Sea Tow, the boat is now in the shop for assessment.

I was wondering what the consensus was on my engine failure. Rods, piston, gimbal bearing etc. All I can say is that it did restart but I did not drive it, clacking metallic sounds were everywhere. The boat did not overheat, no smoke or oil in bilge, but I have not check the oil condition.
As an engineer I am ashamed I neglected to watch the rpm while enjoying my short-lived high speed cruise. Generally speaking what is the weak link? -Besides my driving ability.
I fear I am headed to an engine overhaul. Did I mention, I love boating..?

Thanks for the feedback..

Ps- anyone have a 305 cu in. with low miles, driven by a little old lady boater from Pasadena?
MIKe

 

[cr2k]

Re: Super Genius strikes again-305 Mercruiser Alpha one- Ran perfect-Now toast

Could anything from a piece of carbon coming loose and jamming a piston or valve to a rod bearing, or even a cracked piston. It is teardown time. Let us know.

 

[LX Kid]

Re: Super Genius strikes again-305 Mercruiser Alpha one- Ran perfect-Now toast

You pushed an older engine past it's designed rpm's. It's just like sending an over-weight senior citizen out on a 10 mile run. You made it have a "heart attack!"

 

[oops!]

Re: Super Genius strikes again-305 Mercruiser Alpha one- Ran perfect-Now toast

any idea what rpm you were at?

 

[7362]

Re: Super Genius strikes again-305 Mercruiser Alpha one- Ran perfect-Now toast

any idea what rpm you were at?

I actually did not notice but I was thinking more about this. If I cracked a piston, or threw a rod, wouldn't the engine quit, or seize, or throw oil into the bilge.
I guess I am trying to be optimistic, but after rethinking this outing a few dozen times. I seem to recall the engine started and even was able to idle even though the metallic noise was very noisy and disturbing. Could it be that I blew up the gimbal housing. I don't know much about blowing an engine, but the fact that it restarted seems to me to be a good thing. I am hoping the engine survived.

I will know in day or so. and will keep you posted.

 

[kd7isf]

Re: Super Genius strikes again-305 Mercruiser Alpha one- Ran perfect-Now toast

Sounds like u-joints to me...

Lots of power on old u-joints = boom.

The sound you describe is perfectly in line with what you should here when your ujoints go out.

Could also be a gimbal bearing -- if it decided to go out, it could cause the drive shaft to throw the u-joints all over the place -- and there's not much clearance in their spot....

The sound was coming from the back of the engine, right?

You should be able to go WOT all day if your engine / drive / prop are all matched up properly and all in good shape.
Should top out around 4400 - 4800 rpms... Wouldn't push it past that....

Pull the drive and then run the engine (only for a few min at the most -- no cooling without water coming from the drive) to see if the noise is drive or engine related -- note, running the engine may not be necessary -- if the u-joints are bad, you may be able to tell by looking at them after you pull the drive -- if the shaft sticks straight out rather then falling downwards when you let go of it, the u-joints are seized (i.e. toast)....