piston looks like swiss cheese

joechristo

Cadet
Joined
Jul 1, 2002
Messages
7
I have a 1990 Mercury Outboard 150 Blackmax<br /><br />or I think it is a 90, I have the serial, it is OA99379965663-c1 (Not sure if that is a c1)<br /><br />I finally got the head opened up, took the cover off, and the sixth piston looks like swiss cheese, it is all chewed up like a rock got in there.<br /><br />So that needs to be replaced, calling the marinas around wonderful Rochester, NY. The lowest price I was quoted so far was $900. If anyone will even work on it they usually quote $1800-2000. :mad: <br /><br />I have a friend who is pretty competent with engines, but that power head looks pretty complicated, and it looks like you need to take off most of the engine to get to the other side of the piston.<br /><br />Any suggestions on how I could get this done cheaper? How involved would it be to do this on our own?<br /><br />If I can get the cost down to 500-600, then spending would be justified. I can not spend $1000 right now on this boat. Either way it will probably have to wait until next spring.<br /><br />One more question, would it be cheaper in the off season to get this done?<br /><br />Thanks in advance, this board has been very helpful.<br /><br />Joe
 

Greg Lawrence

Petty Officer 1st Class
Joined
May 18, 2002
Messages
263
Re: piston looks like swiss cheese

well, if you can find a mechanic that works at dealer or something that will do it on the side.. i got a guy that does all my work, he honed a cylider and replaced the rings on one piston for me for 400.00 That is a real bargain. usually that will run you 800-1000 easy.
 

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: piston looks like swiss cheese

You need to find out what caused the failure or it will happen again after the rebuild. Probably caused by lean mixture in that cylinder (carb needing cleaning or rebuild)? Don't know if your motor can be bored or not (some Mercs have chromed sleeves and cannot be bored). Doing just the bad cylinder is OK, though.
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,070
Re: piston looks like swiss cheese

Normally the head would have to be bored out and the cylinder would be sleeved and a new piston installed.<br /><br />You can cut way back on the price if you do most of the grunt work yourself. Removing the powerhead is not too bad just take lost of pictures, notes and label everything.<br /><br />You can purchase a complete rebuilt powerhead on this web site for about 2500 which would put your entire engine in shape.<br /><br />Bob
 
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