Motorola Alternator Dying?

[theMonch]

Having what looks to be an intermittant charging problem. Battery age approximately 6 months, don't know how it was treated by PO in this time as I just bought the car.

I encountered a problem where the battery light came on while I was local driving last sunday, so I brought the car home. I hooked my multi-meter up to the back of the alternator, positive to the stud with the wire bunch and negative to the braket mounting bolt. It looked to be not charging at all. Tryed testing from the battery as well and same results. below 12v and dropping while engine running.

Funny thing now was that I charged the battery back up and tested it again, and now it seems to be working again. It gets just over 13v at idle and 14.21 consistently at off idle all the way to 4k rpm. Its a Motorola and looks to be pretty old. I am thinking that it is dying and maybe on its last leg. I'll have to monitor it to see where it goes.

What do you think? Is there a more definitive test? Could a weak battery cause the alternator not to charge?

There is also what looks to be like a thick black epoxy of some sort that was leaking out of it at some time, but it is dry and hard now. I have attached a picture.

[DMCMW Dave]

positive to the stud with the wire bunch and negative to the braket mounting bolt. It looked to be not charging at all. Tryed testing from the battery as well and same results. below 12v and dropping while engine running.

---
What do you think? Is there a more definitive test? Could a weak battery cause the alternator not to charge?

There is also what looks to be like a thick black epoxy of some sort that was leaking out of it at some time, but it is dry and hard now. I have attached a picture.

The "goo" you see is the potting compound from the regulator. Means it was running hot and is probably at least part of the problem. Sometimes you can replace the regulator and fix it, but you are dealing with a 30-year old alternator and you will often find that taking it apart just breaks thing (screws and connectors).

This is not unusual, i.e. it works cold but not hot, works for a while a quits etc.

Replacing the whole alternator is the expedient route at this point.

[theMonch]

Yeah thats what I was kinda feeling, that it probably is a good idea to go ahead and replace it.

Any recommendations? I was looking at this..
http://store.delorean.com/p-6804-alternator-140-amp.aspx

since I have to order up a few other odds and ends as well.

I dont really plan on running a whole lot of aftermarket electronics (no big stereo,etc) but i do plan on performance upgrades as the needs arise to replace components with ignition, etc.

[DMCMW Dave]

Any recommendations? I was looking at this..
http://store.delorean.com/p-6804-alternator-140-amp.aspx

.

That's the one I like (disclaimer - also the one I sell :thankyou:). There are more generic alternatives but most require a bit of minor fabrication to fit.

If you can, avoid the ones where you hack up the mount on the engine, we've had a few in here like that. It's annoying when you try to go back to something that really fits, and the guy who made the conversion is long gone and didn't bother to document what the cross-over was.

Something to try first if you have the time - and this is important when installing a new one anyway - be sure to sand the rust off the sides of the mount where the long bolt goes, AND take the mount off the engine and clean it up too. The mount is cast iron and corrosion can be an issue.

Also clean (and/or add a second ground path) the braided wire that jumps around the right engine mount. That's the ground path from the alternator and starter to the to the battery and can cause issues as well.

[David T]

The alternator is definitely the problem. The black goo melts out of the regulator and makes the brushes stick. Once that happens they no longer make good contact with the slip rings and the alternator fails to produce electric. If it gets hot enough the goo softens and the brushes make contact. The alternator is rebuildable if you want to go that route. Takes longer than replacing it but costs less. Another possible course would be to replace it and have the old one rebuilt for a spare (or not). To rebuild all you need are bearings, brusholder and regulator. Parts cost about $50. The old alternator may even have some resale value as a core so don't throw it away.
David Teitelbaum

[theMonch]

The alternator is definitely the problem. The black goo melts out of the regulator and makes the brushes stick. Once that happens they no longer make good contact with the slip rings and the alternator fails to produce electric. If it gets hot enough the goo softens and the brushes make contact. The alternator is rebuildable if you want to go that route. Takes longer than replacing it but costs less. Another possible course would be to replace it and have the old one rebuilt for a spare (or not). To rebuild all you need are bearings, brusholder and regulator. Parts cost about $50. The old alternator may even have some resale value as a core so don't throw it away.
David Teitelbaum

Thanks good to know. I think I am going to order up the whole new alternator, but just in case, where can the "rebuild kit" be found? Do you have any part numbers, etc.? I think I will pick up one of those as well and rebuild the stocker to have as a spare.

[stevedmc]

Thanks good to know. I think I am going to order up the whole new alternator, but just in case, where can the "rebuild kit" be found?

If you order the stuff from a vendor call Dave at DMCMW. He is the best in the business and you won't have to explain everything to him again over the phone since he is already reading this thread and knows what you need.

I do business with Dave and Julie (DMCMW) whenever I need DMCH parts and I consider them more of friends than an actual vendor.

Also, DMCMW ships stuff very fast. I am about 4 hours from Houston and about 18 hours from Chicago. DMCMW still gets my business even though Houston is closer.

[David T]

I don't know if the Delorean vendors have or sell the parts to rebuild the alternator. If there is a large rebuilder local to you they should instantly recognize it as a piece from a VW. They will have the parts in stock and probably won't charge much to rebuild it and bench-test it. Don't even mention Delorean. Of course if Dave S can help you, you should always patronize the Delorean venders. When replacing the alternator you might want to replace the belt too.
David Teitelbaum

[theMonch]

If you order the stuff from a vendor call Dave at DMCMW. He is the best in the business and you won't have to explain everything to him again over the phone since he is already reading this thread and knows what you need.

I do business with Dave and Julie (DMCMW) whenever I need DMCH parts and I consider them more of friends than an actual vendor.

Also, DMCMW ships stuff very fast. I am about 4 hours from Houston and about 18 hours from Chicago. DMCMW still gets my business even though Houston is closer.

It's actually funny that you mention this because I was wondering what was the etiquite for ordering from the different DMC dealers. Correct me if I'm wrong, but they are all associated with one another and all source from the same warehouse of parts?

Can anything that can be ordered from store.delorean.com be also ordered from DMC midwest directly as well?

I definetly would want to order from the guys (dave for instance here) that provide tech assistance. I just dont understand the associations and affiliation between them.

[stevedmc]

Can anything that can be ordered from store.delorean.com be also ordered from DMC midwest directly as well?

Yep. The prices are the same as well.


Correct me if I'm wrong, but they are all associated with one another and all source from the same warehouse of parts?

All of the Delorean franchises listed on Delorean.com are associated with each other. There are also a few independent guys that have various opinions of DMCH, but all of that stuff is for a whole other thread.

Just buy your DMCH stuff from Dave and you'll be fine.