1971 Mercury 650 Thunderbolt Alternator problem?

[GENINC]

Hello, new member here....

As the title says, I have a 1971 Mercury 650 Thunderbolt Engine Serial # starting 307....

The problem I have is the following:
The engine starts absolutely perfect, but only if the battery is connected. When the engine runs, and I remove the battery, it dies immediately, which leads me to believe that the alternator may be faulty. Is there any way to check for that? Also, is the alternator and the starter one unit in this engine? Any tips for repair or diagnostics would be greatly appreciated.

Edit: I just realized that this engine probably doesn't even have an alternator... So the problem now is, why it doesn't start without the battery when you use the manual pull thingy (sorry don't know the terminology here).

Regards,

Alex

 

[Laddies]

Re: 1971 Mercury 650 Thunderbolt Alternator problem?

Your engine is battery CD and won't run with out a battery, it has a alternator winding under the flywheel and a rectifier remove the 2 yellow wires from the rectifier and bridge them with a OHM meter if there is continuity the winding is good here's a test for rectifiers.

 

[GENINC]

Re: 1971 Mercury 650 Thunderbolt Alternator problem?

Hello Laddies,

Thank you for the quick reply.

I am really not a mechanic, so forgive me for the possibly stupid question, but what is a alternator winding and rectifier and what purpose do they serve?

Edit: I am not sure if you understood me correctly, will/should the engine start WITHOUT the battery when you start it manually (pulley)? If it only works with the battery, then I don't have a problem, because it does start, both manually and with the key when battery is connected

Thanks
Regards,

Alex

 

[Laddies]

Re: 1971 Mercury 650 Thunderbolt Alternator problem?

The winding under the flywheel produces AC voltage and the rectifier converts the AC voltage to DC to charge the battery to supply the starter and ign. 12 volts to operate with.

 

[Gomer50]

Re: 1971 Mercury 650 Thunderbolt Alternator problem?

May I also suggest not to disconnect the battery when the Motor is running. It can cause major damage to your switchbox,recitifier and stator.

 

[GENINC]

Re: 1971 Mercury 650 Thunderbolt Alternator problem?

Thank you Laddies, I will check the rectifier just to make sure it is charging the battery properly, nothing worse than being stuck in the middle of a lake with a dead battery

Thanks for the advice Gomer50, I will keep that in mind...

 

[hotrod53]

Re: 1971 Mercury 650 Thunderbolt Alternator problem?

I am so glad to see this thread! I recently hooked up my battery backwards, only for a second, and I'm not sure if my battery is charging. I know that a rectifier burn out can be caused by doing what I did. I noticed that mine has a little split in the rubbery potting on the rectifier. I wanted to check it to see if it blew before I ended up on the water with a dead battery. The rectifier is 34 years old, it could be dried up, it could have split to let out the smoke. Thanks for the posting!