Texas Fishing Forum

Blown Piston?

Posted By: 5PounderOnAFrog

Blown Piston? - 10/28/19 03:47 PM

'94 Merc/Mariner ELPTO 115

Motor started fine when launching, docked boat, parked truck and then reversed out of the dock. When I shifted into forward the motor made a popping/releasing pressure sound (Like unplugging a hose from an air compressor) and motor shut off immediately. Tried to restart and it wouldn't even crank at all. After a few minutes the motor wanted to crank but wouldn’t turn over (starter would engage but flywheel wouldn't turn).

-Wires look normal. Battery is brand new only been out on the water one day before today. Graphs reading 12.1v. Trim/accessories/everything else connected to starter battery working fine.

-Everything under the cowling looks normal as far as I can see. No funny smells, smoke, etc.

-Had an intermittent alarm going off a few trips earlier but there was no rhyme or reason to it (random timing, would fade in and out, sometimes while idling, sometimes while on plane, or sometimes before i even cranked the motor). Checked all the usual stuff and nothing seemed out of the ordinary. Figured there was some sort of electrical issue due to the randomness of it.

-Probably forgetting lots of other vital info, feel free to ask and i will try to answer to the best of my limited mechanical abilities.


Hoping It’s some sort of electrical issue but that pop and immediate shut down had me worried that i might have blown a piston. Cranked fine 2 seconds before the pop and shutdown.

Anyone have any ideas what i might be looking at repair wise? Just want to prepare myself for the possible bad news so i'm not caught off guard. Thanks
Posted By: boatman025

Re: Blown Piston? - 10/28/19 06:45 PM

Where you located we are in Wylie and can check it out for you
Posted By: boatwhisperer

Re: Blown Piston? - 10/29/19 01:00 PM

I would pull the spark plugs and look to see if there is any aluminum transfer on the plugs if they all look the same then the lower unit will need to come off if when you take the gearcase off and the flywheel turns fine then the peiblem is in the gearcase if the flywheel still wont turn then you are looking at a serious powerhead problem and a rebuild. I am quite a distance from you but if I canhelpp let me know
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