Ignition wiring on Merc 898

[meat76head]

Okay, so I overheated my 1978 Merc 898 (Chevy 305) a couple weeks ago and now whenever I turn the battery switch to the "On" position the engine tries to start itself.<br /><br />I'm guessing this means I may have melted some wiring causing a short somewhere.<br /><br />Where should I start my search and what should I be checking?<br /><br />I also plan on changing the oil since it's really burnt and addressing the overheat problem (install new thermostat, impeller is fine... exhaust risers were cleaned out prior to overheat).<br /><br />I'm a newbie to working on engines and just am not sure which wiring I should be checking to find the fault and how.<br /><br />Thanks!

 

[rbezdon]

Re: Ignition wiring on Merc 898

If you heated that much you are likely to have more issues than just wiring once you get it started again. Not to sound like a smart a$$ but check and replace all the melted wires!! If you melted the harnesses that control the starter, that engine was REALLY hot. Anything rubber, plastic, etc touching or nearly touching the engine should be repaired. You are lucky the wires didnt melt through to ground and short out and start a fire. By the way, rubber parts include ex bellows, flappers, rubber tubes from risers to y pipes, hoses, etc

 

[Haut Medoc]

Re: Ignition wiring on Merc 898

Try looking at the yellow/red wire. It is probably fried to the red/purple wire. Yellow /red wire should only have voltage with the key in 'start' position. Red/purple will have voltage in 'run' position. Don S. made a really good link on starter wiring, but I don't know where it is. It really should be in the FAQ's. Maybe someone else knows where to find it.....JK

 

[ron7000]

Re: Ignition wiring on Merc 898

find the starter solenoid, odds are that is stuck rather than a melted wire. Could be from the overheat or just coincidence. <br />The solenoid can be on the starter itself or remote mounted, not familiar with that year/model.<br />hammer the solenoid and should unstick it at least for time being.<br /><br />what's your definition of overheat? what did the gauge go to, and for how long?