'87 Merc 3.0L - Broken Piston Skirt

rdc54yty

Seaman Apprentice
Joined
Mar 28, 2004
Messages
49
Whining follows... So I have the motor out of the boat for motor mount former repair. I figure I'll replace some gaskets cause it leaks oil. The engine is upside down in the stand, oil pan is off. What do I notice lying on the block oil pan seat - a piece of the #2 piston skirt. Jeeezzz! I'm half tempted to pretend I didn't notice. <br /><br />So my questions are<br /><br />1. What causes a piston skirt to break?<br /><br />2. What kind of damage should I be seeing on the cylinder wall?<br /><br />3. What is the extent of the repairs I should undertake? Remember this is an 87 motor with other, maneagable, problems. I have no idea about the condition of the other cylinders but the boat still makes top speed at WOT. <br /><br />4. Is there boating god I should be making offerings to so this sh#% stops? <br /><br />Kidding.<br /><br />Thanks in advance for info.<br /><br />Keith
 

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: '87 Merc 3.0L - Broken Piston Skirt

It's a problem with 140/3liter engines, usally don't hurt the cyl. walls, some say not letting the engine get to tempture before high speed causes it and some say excessive RPM. I think it is s--t happens deal---Bob
 

trog100

Senior Chief Petty Officer
Joined
Dec 1, 2004
Messages
751
Re: '87 Merc 3.0L - Broken Piston Skirt

only guessing here but alumimum work hardens over time and goes brittle.. its probably an "ageing" thing.. pistons try and twist in the bores during the power stroke this puts load on the skirt bottom.. the 3.0 is quite a big wide piston.. given plenty of hard use.. "s--t happens".. he he<br /><br />hope it dont happen to my poor old 3.0 thow.. he he <br /><br />trog100<br /><br />ps.. this kinda thing is why airplane wings sometimes fall off.. whoops..
 
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