Motorola Alternator

[David T]

I just had to fix my alternator. The battery light came on, the voltmeter went low and the lights got dim. The alternator had black goo dripping out of it. Upon removing it and removing the regulator (it is attached to the outside so you don't have to disassemble the alternator to remove it) I figured out what happened. The potting materiel melted and dripped into the brushholder. It glued the brushes so they didn't make contact with the slip rings on the rotor causing the alternator to not work. The fix was to replace the regulator and clean the brushholder and slip rings. I got an NOS regulator at a local shop. They use them to fix VW's. Lacquer thinner cleaned up everything and now it works. The voltage regulator can be replaced without removing the alternator but you can't get the brusholder out easily. R & R ing the alternator is not a big job though. This is just an indicator that the alternator runs VERY hot because it doesn't get a lot of air. A long term fix would be to make a small duct that blows a blast of air over the alternator. Just have to engineer it so it doesn't blow any water into it. BTW the alternator should be derated because of the heat. A 100 amp alternator can't make 100 amps if it gets hotter than it's rated operating temperature. This derating applies to wiring also. Now on my checklist when I look at cars underneath is to see if there is any sticky black goo dripping out of the alternator.
David Teitelbaum

[WelmoedJ]

David,

You once mentioned the fact of heting up due to the way the alternator is situated, reversed as the engine is reversed built into the car.

Did you ever consider using watercooled alternator as Mercedes had/has on some models?
Of course that makes need of re-engineering the cooling system, but it might be do-able.

Creating a duct and pulling air over the altenator would not be as effectively as the air either has to blow against the airstream through the engine bay or to the closed end of the alternator.

Your thoughts on this subject, please.

[Bitsyncmaster]

Think you need to do some testing. Put a thermocouple on it and see if it runs warmer at highway speeds or idle. Is there any data on the air flow in the engine compartment?

[David T]

I don't like the idea of mixing electric and water. The cooing system has enough connections already. Air is the easiest way. I agree at idle it won't work but typically when you are driving, the car it is moving most of the time. Maybe there is a way to modify the fan that's already on the alternator so it is more efficient. Using the cooling system in the car means you will never have the alternator below 180 F once the motor is warmed up. Should be able to do a lot better than that with air.
David Teitelbaum

[DMCMW Dave]

As ("on hiatus") Bill pointed out the fan on the alternator is attempting to blow air into the alternator from the belt end. Of course going down the road the air is going the other way, so the net is not much airflow when the car is moving. Anyone want to develop a reverse-flow fan blade?

[Bitsyncmaster]

As ("on hiatus") Bill pointed out the fan on the alternator is attempting to blow air into the alternator from the belt end. Of course going down the road the air is going the other way, so the net is not much airflow when the car is moving. Anyone want to develop a reverse-flow fan blade?

But is the air flowing from front to back in that location? It's not a laminar air flow in there.

[David T]

All it might take is just carefully and accurately bending the fan blades. As they are now they are basically flat. Or maybe just removing the fan? This is a good place for anyone who wants to experiment and come up with a good mod. If you can get the alternator to run cooler it is better than trying to put a larger one in. BTW the airflow in the engine compartment is horrible from an aerodynamic point of view in general. On Lotus's they were able to improve it with a diffuser under the rear facia. Also added some downforce for better handling.
David Teitelbaum

[Bitsyncmaster]

Boy this could get complicated. How could we measure the air flow through the generator?

[dmc]

I remember browsing on aftermarket performance alternator web site (maybe mad electric or power master) and they showed that the fan blade on a oem alternator sucked air through from back to front. In a normal car this would be against the tide so to speak. Nowadays most oem's don't even have a fan.

[TTait]

It might be worth trying something similar to Grady's approach to the AT cooler, and look at heat sinks that can be effectively applied to the casing of the alternator... It would look dumb but I'll bet it would be effective.

[AdmiralSenn]

Or switch to a more modern alternator design with an internal fan that isn't direction-sensitive?

Not that I've done this, but I've seen a few success stories on the old forum from people who have.

[Bitsyncmaster]

Here is a test that would be interesting for people with an infrared temp reader.

Check your new car daily driver's alternator temp after a drive. Then check the D's temp after a similar drive and post your results.

Maybe the idea that high temps killing ours are are dumbfounded.

[Grover]

It might be worth trying something similar to Grady's approach to the AT cooler, and look at heat sinks that can be effectively applied to the casing of the alternator... It would look dumb but I'll bet it would be effective.

You mean like this?: http://store.alternatorparts.com/7130-cs130-series-iceberg-finned-alternator-upgrade-kit.aspx

I have been posting about this to the forum for a long time. This is what I had done to my Alternator. It contains a more robust regulator, better bearings, and a heat sink finned housing.

This link shows the heat of the regular case vs. the iceberg, showing the heat dispersed more evenly. http://www.nationsautoelectric.com/Iceberg.html

[jmpdmc]

I have some info to share based on Bitsync's request. I have measured some engine compartment temperatures over the past year in my DeLorean at various locations using a Kintrex IRT0421 (a basic $50. infrared thermometer). One place I tested was the alternator case. I just measured my 2 daily drivers based on the request. All temperatures in Fahrenheit and all cars driven till fans cycled or 24 miles (distance from work).

Date Car Ambient Temp. Alternator Case Temp

11/7/10 1981 DMC with stock 43 degrees 122 degrees
exhaust and D110
alternator

04/23/11 Same 63 145


05/26/11 DMC at DPI with upgraded 78 170-180
cams and non-ceramic
coated DPI Spec 1 exhaust
unknown alternator

06/26/11 Same as 1st car 65 140-146


10/6/11 2004 Toyota Solara 70 153-170
stock alternator

10/7/11 2008 Toyota Rav4 58 142-166
stock alternator


In this brief sampling, the DeLorean alternator (a D110 in my case) does not seem to be out of line temperature wise with 2 modern day Toyotas. The ranges are there since I measured several different spots and put the lowest to highest on the chart. Maybe someone has some additional info they can add to this but here are my findings.


Jeff

PS Sorry the post looks weird but it looks fine in the reply box. I can't see how to make it look easier to read but everyone should get the picture.

[Bitsyncmaster]

PS Sorry the post looks weird but it looks fine in the reply box. I can't see how to make it look easier to read but everyone should get the picture.

Thanks for that info. You can see your post with the proper "tabs" by opening the post in a reply. I've had that problem trying to make tables in my posts also.

[Dangermouse]

Try this

[jmpdmc]

Much better Dermot, thanks.



Jeff

[Bitsyncmaster]

So far with that first set of data, our alternators are not dyeing because they are overheating. Not saying it would not work better if you could cool it but would it be worth it?

[Grover]

I will have to take some temp readings with the Iceberg Kit installed on mine...

[Ron]

Anyone have the OEM voltage regulator and/or alternator number? I have a Delco on mine and want to see if the are in my rebuild spec sheets.