LOST COMPRESSION - HELP !

[Bob Hockham]

Subject: Mercury 15 HP compression problem.<br /><br />Good day, can you please assist me.<br /><br />I have the following outboard motor:<br /><br />Mercury 15 Hp<br />SN 09896595<br />Built 1996 15 MH<br />6000 Max RPM<br /><br />HPLB 15/75<br /><br />KWKG 11.2/34<br /><br />Manuf Marine Power Belgium CE 95<br /><br />Problem:<br /><br />Engine has allways been very reliable and now we cannot start it.<br /><br />I have taken it to a local repair company they serviced it but tell me<br />problem is low compression (Getting only 2 Baar when cylinder pressure<br />should be<br />6 Bar).<br /><br />As the engine is located in Greece the local repair companies are not very<br />reliable.<br /><br />I would like to repair the engine myself, but what I would need is:<br /><br />1. Your advice.<br />2. Idiots guide to overhauling this engine.<br />3. Full set of spares and recommended tools to do this.<br />4. Neccessary manuals.<br /><br />I would greatly appreciate your assistance.<br /><br />Bob Hockham.<br />Southampton, England.

 

[lonewolf5347]

Re: LOST COMPRESSION - HELP !

WHAT YOU CAN TRY IS TO DECARB. THE ENGINE MAY GET LUCKY .

 

[slow_boat]

Re: LOST COMPRESSION - HELP !

Hi,<br /><br />I would check the compression myself if you feel the local repair shops are unqualified. A decent tester should be available at an auto parts store. It is not hard to do...first buy a manual for your engine...well worth the price.

 

[aeronutt29]

Re: LOST COMPRESSION - HELP !

Since you are a new member here I'd like to suggest that you spend some time using the search feature of this board. You will find a LOT of information on how to decarbon the engine, test compression, clean the carbs, rebuild the fuel pump, troubleshoot electrical problems, and just about everything else that can possibly cause a motor to run poorly. <br /><br />I strongly suggest getting that motor home so you can work on it yourself. The first thing you should do is repeat the compression test. If the compression is really as bad as you said then it's likely that the motor is badly carboned up and has stuck rings. Perform a thourough decarboning and try the compression test again. <br /><br />If it still has bad compression then the news isn't good. You will be tearing the motor apart to replace internal parts. Don't buy any new parts until the motor is in 100 pieces because you might find that the damage caused by a few broken rings rattling around on top of the piston is bad enough to warrant buying a whole new motor. That would obviously be the worst possible scenario and I sincerely hope that it doesn't come to that.