merc 470, 170hp starting problems

[sputnam]

the engine will start, but then after it heats up while underway I noticed the engine temp gets to about 160 so I pull off and head to the shore to let it cool off and then it wont start. The voltage just drops straight down and nothing. I still would show about 15 volts on my gauge, until I try and start it and then it just drops. A few hours later or the next day it will start up again. I just took it to the shop and basically they thought they "fixed" the problem because started right up. I took it out the next day and everything seemed fine until I got about 1-2 miles from shore and the same thing.The only thing that I did this year, since it ran fine last was put new wires on. I'm thinking the thermostat but I'm unsure because i'm am not that familiar with merc engines, but that would be on of my first guesses on a car.... Please help.

 

[tommays]

Re: merc 470, 170hp starting problems

i am not a 470 expert but 160 is not over heating<br /><br /><br />so no clicking or anything ? a service manual with a wireing diagram will show you were to check for 12 volts till you find were its stoping <br /><br />the starting could be anything i would have the battery load tested a cell on the way out or just and old battery can not put out enough amps to crank the motor more so when its hot<br /><br />after that you have to start looking at bad connections or bad cables <br /><br />tommays

 

[Don S]

Re: merc 470, 170hp starting problems

The 470's usually ran right around 180° so it didn't even get warmed up good. Unless you meant 260° instead of 160° then you have a problem. The first place to look would be the raw water pump impeller in the outdrive. They are only good for 2 maybe 3 years.<br />Regarding your electrical issue, you say your gauge showed 15 volts with the engine off. My guess is you have fried your battery. The 470's have a charging system simalar to an outboard and the regulators will go bad and cause high voltage (Over 16 volts) while running that just boils the batteries to death. Check the voltage with a VOM or DVM at the battery to see if your gauge is reading correctly also.<br />Loose, corroded connections will also cause your no crank problem.

 

[sputnam]

Re: merc 470, 170hp starting problems

Thank You for your replies, The temp was about 160. The battery is about two years old and I forgot and left connected all winter long?! Could this be the problem? I did charge it and it took a charge. And I replaced the voltage regulator at the begging of last season.