Volt Gauge, and Motorola 90 Alt. VS. 140Alt.

[refugeefromcalif]

Hey all.
I did a little searching here and couldn't find answers to my few questions. (Hence this thread).
Also, Because I sometimes feel that Bigger is Better, (No Jokes please ), I've ordered the Motorola 140 amp alternator to replace my 31 yo. 90. (Which still works).

Since I got my car back from DMC Florida, I've noticed that the Volt gauge seems to register a bit lower, (than it used too), with different loads on the system.
The only additions to the electrical system was a Wing-A-Loft.
(Granted, I Do need to re-check all the grounds and see how they are).

As kind of a Baseline, I was wondering if the following pics, (All sitting at Idle in my yard), are about Normal in a 90 amp. Alternator situation, with the described loads for each.
(Excuse the dust, 6599 needs a Major cleaning)...


Sitting at Idle with nothing on.


In Vent mode, fan turned to 4, (High).


Adding headlights,


Now turning A/C on to Max. (Fans still on 4).


My other question is, does my temp gauge reading look Normal? As these pics were taken, the air temp is about 75. Even at the 95+ temps we had a few weeks ago, (A/C on), the needle stays at this level.
When A/C isn't on, I've never seen the gauge get more than a needles width beyond the pictured line before the fans kick on.

If I need to clarify something, let me know.

Oh, Is the Motorola 140 alternator worth the upgrade?

Thanks in advance.

George

[Chris Burns]

Going to a Delco CS-130 is my recommendation. They are slightly cheaper.

[refugeefromcalif]

Going to a Delco CS-130 is my recommendation. They are slightly cheaper.

Is the Delco Better? Or, just cheaper? Is it a Direct bolt on replacement?

Well it's moot point now. I've already ordered the Motorola 140 from DMCH.
I was looking for a Bolt on replacement and figured I'd support a DMC vendor.

George

[Chris Burns]

Is the Delco Better? Or, just cheaper? Is it a Direct bolt on replacement?

Well it's moot point now. I've already ordered the Motorola 140 from DMCH.
I was looking for a Bolt on replacement and figured I'd support a DMC vendor.

George

I will tell you this. The Delco CS-130 works very well. My friend Oliver has it on his BTTF Delorean and is able to handle everything

Some mods do have to be made in order to make it work, but it is well worth the effort. Pulley has to be swapped, holes have to be made slightly bigger, and different type of belts have to be used.

[Kenny_Z]

Those levels look exactly like my old 90 alternator would output. The temp gauge looks normal to me as well but I'll let guys with more DeLorean experience chime in on that. I think the 140 would be worth the upgrade. I didn't use it though, I installed a Caddy alternator that I think is 110. I can't remember.

[kings1527]

Hi George,

I was in a similar situation last year but my volt meter never worked right until I added Hervey's double ground cable. Once I did that, my voltage reading at idle is extremely accurate yet a little higher than yours. When I bought my car, I had the Motorola still in it but like yours, mine was working just fine. I decided to go with the DMCH 140A so I'd never have to worry about it and I've been very happy with it. The DMCH unit is drop in place although you'll have to change the electrical connection on the small wire (takes 2 minutes, if that).

At idle, I read about 14.25V via a multimeter. It puts out great power, even at idle. Your other readings seem low to me, too. Like you said, double check your grounds and check the voltage with a multimeter.

There's a chance that your Motorola is finally giving up the ghost but you'd have to measure it first. IMO, you can't go wrong getting the 32 year old alternator out and putting in a new one. The Motorolas were historically VERY stout but I want to be able to drive my car wherever whenever and psychologically, a 32 year old alternator wasn't affording that. Now, I wouldn't hesitate one second taking my car cross country if I wanted to.

As far as your temp gauge goes, that looks low too (depending how long you had the car idling for). Do your fans kick on/off where they should in relation to the temp gauge? Maybe you really are looking at a bad ground causing things to read low.

From your Dunmurry brother, 6575.

Edit: one thing to note too is that I never had a properly working volt meter prior to Hervey's cable. I'm not sure where my meter would've been with Hervey's cable and the 90 amp Motorola.

[dmc6960]

These voltage readings are typical of a bad bulkead/frame ground. Try cleaning both sides of the ground bolts on the bulkhead connectors. You'll need to remove the rear wall to get to the inside side. Then you'll also want to clean the ground source on that, which is a frame ground to the right of the engine. It could also be a bad battery ground but the bulkhead ground is much easier to get to.

As for the temp gauge, this is perfectly normal as that's where your thermostat is set at. With the AC running and the cooling fans running, it should rarely go over that. With the AC off and the engine idling for a long while, it should go about halfway from where it is now to the 220 mark where the cooling fans will naturally kick in.

[Ron]

$.02

Confirm your readings with a volt meter connected directly to the battery. If you get similar readings try this:
Ensure the belt is tight.
Take a set of good jumper cables and connect one cable between the battery (-) and the alternator case/bracket.
Connect the other cable between the battery (+) and the main (+) terminal on the alternator. This will eliminate all ground and other wiring except the field circuit feed, which is OK if the alternator puts out at all. If readings are still abnormal, you need an alternator.

[kings1527]

Take a set of good jumper cables and connect one cable between the battery (-) and the alternator case/bracket.
Connect the other cable between the battery (+) and the main (+) terminal on the alternator. This will eliminate all ground and other wiring except the field circuit feed, which is OK if the alternator puts out at all. If readings are still abnormal, you need an alternator.

Never knew that....thanks Ron!

[kings1527]

I was just doing a little research on the cable test that Ron referred to and came across another test on another website. They say to start the car, take off the negative terminal from the battery (some are saying positive terminal), and if the car dies then you know the alternator is bad. You might have to place it under more of a load with lights on, AC on, etc.

Some were saying that on an OBDII car it's not good to do that but pre-OBDII is OK. Can anyone confirm that that test is worthwhile or even OK to do on our cars?