Altenator on 3870-gctid356149

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I have the Chrysler/Mitts and need a new Alternator. Last summer I went to the Island and moored up. later that evening once the engines were cooled I did a normal check of the engine room paying attention to the starboard alternator that has been slipping (the bolt connected to slide bar has come loose a couple of times, once shredding the fan belt causing me to lose the engine at night). I noticed the casing on the alternator the triangle shaped piece, that is actually part of the alternator, that the screw goes into was cracked. I gave it a nudge and it broke... With limited on options, I remembered a post a few years ago that i started about a water tank link. Doug explained the many uses of JB Weld and the importance to carry some in the tool box. (thanks Doug) I got out the JB Weld and welded the casing with the screw back into the arm slide bracket. I only had a 23 mile ride back to port so I decided to risk it. A couple of days later we powered home and it held beautifully.

Now I need to replace the alternator. The alternator is a Motorola 8R620098V12 and I can find nothing about it on the Internet. The wiring is kind of out dated as well. Does anyone know of a suitable replacement alternator?

Also, I believe I will need to heat up the JB weld to remove the screw and alternator. Does anyone know what type of torch will do the trick? will the less expensive propane torch get hot enough to soften the JB Weld?

Thanks in advance!

[boatworkfl Supporting Member Find all posts View Profile Close boatworkfl]

Go online to DB Electrical, also found on ebay, they have great prices and may be able to match you up with one.

http://www.google.com/url?sa=t&rct=j...CEYFSJH2B2K0kg

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I had a similar problem last fall & had to replace both alternators, as well as fix the wiring that the PO had completely screwed up. I went to an outfit here called Harbor Marine with one of the old alternators (same as yours, Motorola), and they were able to cross reference it to a Sierra alternator. I will get the Sierra part # for you if you are interested. Sorry, but the paperwork is down on the boat. The units fit right on the engine, no changes needed, & same wiring. I believe they were 50A alternators.

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Scott,

I am very interested in the information.. Please let me know when you get down to the boat and thank you!

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Bryan: Just got back from the boat. The alternator replacement I used was Sierra 18-6263. Bolted right on with no problem, and the electrical connections were a perfect match. As I said, I had to do some re-wiring due to the PO messing it up. He had both engines tied together charging the start battery, nothing charging the house battery. What a mess. I got it all redone so that the Starboard engine now charges the house like it's supposed to, the port charges the start battery, and just to make it better they are tied together through an isolator so that once the start battery is charged both outputs will go to the house. Works well, no more problems. Let me know if this helps.

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This is a very typical alternator used in marine applications. It was on my old GM 350 and on my Perkins 4.108 Diesel I'm repowering my boat with.

This is the alternator I'm referring to:

http://www.ebay.com/itm/NEW-Delco-Ma...item1e684910b7

Check the specs, but you can get a 110 amp unit for much less than the Sierra unit.

[boatworkfl Supporting Member Find all posts View Profile Close boatworkfl]

Astral Blue wrote:
This is a very typical alternator used in marine applications. It was on my old GM 350 and on my Perkins 4.108 Diesel I'm repowering my boat with.

This is the alternator I'm referring to:

http://www.ebay.com/itm/NEW-Delco-Ma...item1e684910b7

Check the specs, but you can get a 110 amp unit for much less than the Sierra unit.

I will be ordering this as a spare on my 3870, Pat S. They can also install a duel belt pulley if you need it for $10 they quoted me.

You can get this as a 1 wire or 3 wire version, rebuilding is about $22.00 for the kit on ebay.

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Scott I really appreciate it.. i will let you know how it goes after I install them..

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Ed thank you as well.. That looks like it might work as well.

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Ed: Absolutely correct. I lost that information or would have passed it on. In my case, I started on a trip with the Admiral & 3 grandkids on board, discovered I had 2 alternators that had decided to try an "alternate" lifestyle, had to turn around back to our slip with 4 unhappy people. Long story short, I needed to replace those alternators "immediately"! Which I of course did. I later found online the higher amperage, lower cost alternatives, but when you gotta, you gotta! Certainly if you are not in a big hurry, do some shopping around. I have to agree that I paid a premium for those two alternators!

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I just purchased two of the 1 wire's for $66 each and free shipping. they have a 1 year warranty and the seller has a high rating with e-bay so i think it is worth a try. The 1 wire seems pretty simple to install so I will give it a go. I will update this after install and let everyone know how they work. Thanks for all the advice, this literally saved me at least $400..

http://www.ebay.com/itm/140661477619

PS, Does anybody have any ideas on how to break through the JB weld? should I just crank with a socket or will I need to heat it up?

[boatworkfl Supporting Member Find all posts View Profile Close boatworkfl]

FishingFool wrote:
I just purchased two of the 1 wire's for $66 each and free shipping. they have a 1 year warranty and the seller has a high rating with e-bay so i think it is worth a try. The 1 wire seems pretty simple to install so I will give it a go. I will update this after install and let everyone know how they work. Thanks for all the advice, this literally saved me at least $400..

http://www.ebay.com/itm/140661477619

PS, Does anybody have any ideas on how to break through the JB weld? should I just crank with a socket or will I need to heat it up?

Remember, with a 1 wire alt, when you first start the engine, you need to goose the rpm's up to get the alt to start charging, you will see the voltage on the volt meter increase, then you can idle and charge.

[Chief_Alen Guru Find all posts View Profile Close Chief_Alen]

I have lost count how many items i bought from dbelectrical. I have bought items for automotive use also.

I cannot recommended them enough, price ,shipping they cannot be beat anywhere.

[BLCarl Frequent Contributor Find all posts View Profile Close BLCarl]

Be aware the one wire unit might cut out at idle and you will have to bump the throttle to re engage it. A real anoyance for me while troling or running in long no wake zones. Two extra wires are not that hard to figure out.

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BLCarl wrote:
Be aware the one wire unit might cut out at idle and you will have to bump the throttle to re engage it. A real anoyance for me while troling or running in long no wake zones. Two extra wires are not that hard to figure out.

I am running a pair of the single wire 10si's.

I've not seen one cut out, but would not be surprised if trolling at low rpm for a long duration.

BTW; The jumper can be added or changed on the 1 wire 10si alternators.

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