Mercury 150 HP Rebuild Dilemna

yeesh

Cadet
Joined
Jul 20, 2012
Messages
19
My 1999 Mercury 150 HP outboard threw a connecting rod last week. Motor always ran great, had only about 550 hours on it. No oil alarm (alarm in working order); not overheated at time of seizure. Running about 4000 rpm. Toying with the idea of purchasing a rebuilt powerhead from one of the larger well-known outfits on the internet and carefully transferring old parts to new. The problem is : not knowing what caused the event in the first place, I don't want it to happen to new motor. Besides oil injection (which I will eliminate by manual mixing), and leaned-out carbs (which I will get rebuilt), are there any other causes other than "bad luck" that I need to worry about ?
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Timing, cooling and a lean fuel mixture are usually the culprits, provided your oil injection and bearings are working properly. So, after installing the new block, replace the thermostats, clean the carbs, rebuild the waterpump and poppit valve, and do a link and synch.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
If it was 1,3,or 5 cylinder the advance/stabilizer is bad. Set the timing at 22 degrees cranking..
 

yeesh

Cadet
Joined
Jul 20, 2012
Messages
19
All good info. That's what's great about this site - the expertise ! Thanks for the advise.
 
Top