Starting concerns

[brimel1]

Hello everyone,

My name is Brian and I'm new to this forum and boat ownership. I'm a master ASE certified mechanic and work for Ford Motor Companies engineering division helping ford dealerships across the US and canada fixing difficult vehicles. I have a vast knowlage of vehicles and electrical systems. However, my boat knowlage is at a novice to average level.

I recently purchased a 1989 stingray svc210 cuddy with a merc 488 3.7L, alpha 1 gen 1 outdrive. Among several issues with the boat I've already corrected, i feel that I'm still having some electrical concerns.

Intermittently, when starting the engine, the starter will not disengage. It continues to spin with the engine flywheel until shutting off the key. Originally, the engine would only crank when i bought the boat, after performing an inspection of the ignition system, i ran a jumper from coil positive to battery positive and the engine started. I can only gather that a faulted circuit from the ignition switch to coil is present? Anyways, this boat was converted to a conventional 1 wire marine generator. I noticed with the engine idling, no voltage was present from the generator B+ post, at 3k rpm, it charged .6 volts. I installed a new generator which charged approximately .6v at idle and 20v at 3k-3500 rpm. With the engine running i took this measurement with the B+ cable removed from the generator. The engine started normally, when i touched the generator cable to the B+ post, the starter immediately engaged and disengaged when i removed the cable.

Before replacing the generator, i noticed that when starting the engine with a battery charger connected, this concern would never happen, coincidence? Is this voltage related? I know that 20v charging at 3k rpm and above is not characteristic of a charging system.

I removed the starter and checked the return spring strength of the bendix, all normal.

Please guys, if you have any suggestions I'm all ears? Additionally, does anyone have a good source for a wiring cell on these engines/boats?

Thank you in advance, i look forward to discussing this.

Brian.

 

[Bondo]

However, my boat knowlage is at a novice to average level.

Ayuh,....... Welcome Aboard,..... Novice for sure,..... The 470 is the least desirable Merc power unit ever devised,....

Click the link in my signature titled Don'S Adults Only Section,.....
In there find the Merc service manuals,......
You'll find yer motor,......

You've got some serious wirin' issues goin' on

Anyways, this boat was converted to a conventional 1 wire marine generator.

That's a common conversion, as it originally had a stator, 'n water cooled voltage regulator, much like an outboard motor,....

 

[brimel1]

Well.i suppose if you must point out I'm a novice because i bought a 488, that's your prerogative. As i stated, I'm in the know as far as having an electrical issue, I'll reference your "adults only" section again and figure it out. Thank you.

 

[Scott06]

What he’s pointing out is that the engine you have is known for issues mostly very sensitive to over heating and blowing head gaskets and cam seal/ cam wear that causes antifreeze to get into the oil, plus the original charging system that was upgraded on yours.

If you don’t know when the impeller in the out drive was changed I’d change it now using oem parts. Additionally check that you have a clean 4” heat exchanger that should keep it cool and not blow head gaskets. There are guys on here with more knowledge on this engine that keep theirs going on here to help you, but as bondo started most steer clear of this engine.

Given the expertise you state, you should be able to trace out the electrical and handle the issues common on this engine

 

[brimel1]

Thank you Scott. I can handle the electrical issues, I found a wiring diagram for the charging system conversion on this boat. I ordered a 1 wire alternator, however it appears I should wire in a 3 wire alternator. Also, I did pull the caps off of the heat exchanger, all is well and clean. The cooling system holds pressure when tested and while running the boat, the temperature gauge remains cool, no overheating issues as of yet. Engine runs strong thankfully, I hope I don't get any issues with the engine like you guys and several other forums I read have suggested. The oil is clean and free of coolant/water. I've already replaced the impeller in the lower drive. Again, thank you for your time and knowledge.