1977 850 thunderbolt starter wont engage

[ccarpen4753]

I have a 1977 mercury 850 thunderbolt (85hp). I cant get it to start. I replaced all the wiring. I removed the old wiring harness and built a new one. The neutral safety switch and the mercury switch have been removed. It has a rebuilt starter and new solenoid. Has new battery cables. I got it to start and run on starting fluid, but after about 15 min of repeatedly starting it then the starter quit engaging. It wasnt hot to the touch. The solenoid will just click now. I changed the solenoid out with another one and had the same result. Checked my voltages and am getting 11.5-12v across both solenoids that I used. I can sometimes get the starter to kick when I put both battery cables on the starter, but not every time. Checked my ground connections and all seem good. I had muffs on it with water running every time I tried to start it. Also had my truck with jumper cables hooked up to it to make sure I had enough power. Im stumped bc it was engaging the starter fine then just stopped. Any help would be appreciated.

 

[ccarpen4753]

pics

 

[Chris1956]

Time to inspect the brushes in the starter.

 

[ccarpen4753]

It is a rebuilt starter that I just put on. Only used it like 30min. Could it have went bad already?

 

[Chris1956]

One would not think a rebuilt starter would break so quickly. Was it rebuilt at a shop, or was it bought used?

When you buy a used starter at the local salvage yard, they test it by connecting to a battery for 2 sec. If it spins they consider it good. If it breaks for you when you get it home, they will give you another and trash the first one.

 

[racerone]

It is simple to inspect that starter yourself.----That is the next step to take.---Yes they are easy to work on.---Ask questions once you have it apart !

 

[ccarpen4753]

It is a new starter that I purchased off ebay. I pulled it off today and hooked to my battery charger and it wouldnt engage @ 50amp.

 

[Chris1956]

Well, time to take it apart and see what is wrong, or better yet, see if the seller will exchange it.

 

[racerone]

Some new starters marketed on FLEABAY are from a far away place.---Name starts with a C as well.----You get what you pay for I think.

 

[ccarpen4753]

ya i know. ive bought starters from this place before and had good luck. Guess I got a bad one this time. Too bad I bought it like 2yrs ago and just now got around to workin on the boat

 

[ccarpen4753]

ill tear into it tomorrow and post pics to see if you guys can help me fix it. Thanks for the responses.

 

[ccarpen4753]

Tore it apart and didnt see anything damaged.

 

[ccarpen4753]

Ill try to upload pics later today. Everything looked brand new.

 

[Chris1956]

Chect the commutator with an ohmmeter, to see if the windings are open. The field is permanent magnet, if it is like OEM. Should be 4 brushes, if like OEM. See that they are clean, the springs are good and they are connected. I don't remember if there is a bi-metal circuit breaker, but look around for it and clean it, if it exists.

 

[racerone]

No ---no fancy bimetallic circuit breaker on starters !--------Digital ohmeter and take a reading from shaft to commutator.

 

[DavidMoore]

No Title

Could be way off here but it looks like there is a wire missing. My starter has a wire running from that unused contact at the top of the starter to the engine ground. see sketch attached

Maybe someone with knowledge of this specific engine could confirm / correct.

 

[Chris1956]

David, you may be on to something. That starter should have a ground wire bolted to the case of the starter. I cannot see the connection n the pictures, but the ground wire is under the bolt on the starter top mount. She no workee without it.

 

[DavidMoore]

That's what I was thinking, the starter needs to be grounded and I can't see from the picture that it is. Normally it would be isolated from the top mount via the rubber sleeves so ground cable is needed.
It might have been be grounding out via the contact of the top flange and engine block but no way would this be reliable and could cause the exact symptoms described.

 

[NicoPags]

good ground is needed. However, in your case didn't you say you tested starter directly to battery cables and still no engagement?

 

[ccarpen4753]

No Title

David, you are right I am missing that wire to ground the starter out. I havent had this motor running since I have had the boat and wired it up like it was previously so that may have been the problem all along.

On testing the starter, what is the commutater?

FYI I dont think my battery charger is working at the higher voltages, I have been having issues using it lately.