Sounds like Metal Crashing on Metal

Ok...can anyone provide advice on how to diagnose the most recent engine catastrophe...?

My wife was navigating us into our favorite fishing spot and may have had the button on the throttle pulled when she shifted into neutral and accidently shifted into reverse. She turned off the engine which sputtered a bit and when we tried starting it again, it sounds like gears grinding or metal crashing on metal.

Is this a jammed gear drive?

Any help is greatly appreciated.

Re: Sounds like Metal Crashing on Metal

Pull the spark plugs out and see if there is water in the cylinders. Turn the engine by hand.
If you can't turn the engine by hand, pull the drive and try.

Re: Sounds like Metal Crashing on Metal

When you say pull the drive...where exactly is the drive and how would I do that exactly?

Re: Sounds like Metal Crashing on Metal

jkuk said:

When you say pull the drive...where exactly is the drive and how would I do that exactly?

Click to expand...

The drive is the large black piece of rubbish hanging off the back of the boat. The bit with the prop on it. What engine set up are you working on? Let's start with year (of the engine not the boat), model and serial number.

Re: Sounds like Metal Crashing on Metal

The drive I am referring to is the outdrive aka sterndrive. Exactly how to remove it, impossible to say since you never thought to tell us what you are working on.
Look at this thread for more details of what we need.

http://forums.iboats.com/showthread.php?t=220416

Re: Sounds like Metal Crashing on Metal

Welcome to iBoats.


I wouldn't waste time trying to figure everything out on the drive until you do the first part of Don's test.

"Pull the spark plugs out and see if there is water in the cylinders. Turn the engine by hand."

If there is water in there, you want it out ASAP, and squirt some oil in there.

The assumption being the rapid reverse created a large backwash that went past your exhaust shutters and into your engine via open exhaust valve. The engine hydrolocked and your starter engagement began to remove flywheel ring teeth.

Re: Sounds like Metal Crashing on Metal

Ok. Thanks for your patience working me through this.

First, the engine is a Mercruiser Serial No: L630609

I pulled the spark plug and there didn't appear to be water in there, however it may have drained out since the incident.

Pulled the Block Drain and a significant amount of water drained from there.

The two fly-wheels in front do not turn, nor does the shaft underneath the engine, however the propeller does turn.

Also, the bolt holding the starter on came loose, so I rebolted that on.

Any thoughts or next steps for me to take?

Thanks again for your help.

Re: Sounds like Metal Crashing on Metal

3.0L alpha drive???

Did you pull all the plugs and squirt some oil in there?

With the verticle cylinders of the 3.0L, water would not easily come out without turning the engine over.

Put a large socket on the center bolt of harmonic balencer with a three foot ext bar.

Did you look at the starter drive gear, but more importantly, the flywheel ring gear? Regardless of reason, I think that was the noise you were hearing.

Next step, per Don's post, remove drive.

- Put in forward gear.
- Remove speedo connection
- Remove power trim cylinders
- Remove six locknuts
- remove strearndrive

Of course a Service manual will help with the small details and pictures

Re: Sounds like Metal Crashing on Metal

From what I'm reading here...this sounds like a project marked "Difficult" in the Mercruiser Service Manual. Boat is currently in the lift, is it possible to do this work in the water or should I tow it to a mechanic? Any estimate on minimum cost to repair?

Re: Sounds like Metal Crashing on Metal

jkuk said:

should I tow it to a mechanic?

Click to expand...

No offense, but the answer is "yes."