New Alternator!

theartur2000

theartur2000

Daily Driver
Well I got the car into the shop after struggling with this charging issue for several months. They checked all the wires and the alternator and the voltage regulator and they said the wires are all good but I need a new regulator and alternator. I have already replaced the regulator so all that's left is the alternator.

The only one I found that seemed decent was an ultima 45a alternator.

I should mention I have a 1975 x1/9 non-ac with a marelli stock unit.

Should I just go with the cheaper ultima alternator or shell out the cash for a NOS alternator? Is it advisable to go for a bosch unit with an internal regulator? What kind of options do I have?

Thanks!
 
Have you checked to see if just replacing the regulator solved the charging issues? Often that is the problem and the alternator itself does not need to be replaced. Many shops will say you need both but that is not always true.

If you need the replace the alt. I'm not sure what options are available for a '75 X. But if possible I'd recommend a greater output than 45 amps. There is more load now than when the car was new; partly due to options that may have been added, upgraded accessories, and/or old wire harnesses/connectors/components/etc. And 45 amps was barely enough then.

Have you looked into the possibility of having your old unit rebuilt by a local speciality shop? They can even increase its capacity (output) in the process.
 
I got the charging system checked out at a parts store and they said it was a bad voltage regulator so I replaced it with a new one. I got it tested again and they said the same thing even though it was a new regulator.

I'll see if I can get the alternator off and try to take it to a shop for a rebuild.

This might not help but another thing is the alternator light glows dimly when running, then gets dimmer when you raise the RPM. The voltage at the battery stays below charging voltage.

OCCASIONALLY and very rarely the light does go away and the alternator starts to charge again. Maybe I caught it on the way out?
 
theartur2000 said:
I got the charging system checked out at a parts store and they said it was a bad voltage regulator so I replaced it with a new one. I got it tested again and they said the same thing even though it was a new regulator.
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I've had similar experiences. After the third store told me a different story I decided to stand over the guy and watch him test it. Clearly he did not understand what he was doing nor how to use the testing machine. Turns out they were all wrong. Took the unit to a real alternator/starter rebuilder. He tested it (for free) and said the regulator was going out. I replaced the regulator (purchased online very affordably) and asked if he would recheck it. It was perfect. That was with a Bosch unit that uses a "internal" regulator on the alt. The diodes are part of the regulator so replacing it corrected the problem (if one diode is not working you only get a partial charge). I'm not certain what arrangement your Marelli alt has, but I'd not trust the parts store guys either way. See if there is a real rebuild/repair shop in your area.
 
I was contemplating replacing my 32 amp Marelli unit with external regulator with a later Bosch unit with more capacity. I investigated the GM alternator conversion path but quite frankly I did not see any professional looking solution to the mounting issues, and it really did not appear to be a whole lot cheaper. From what I understand, the Bosch units are pretty much drop in replacements, and the existing external regulator is not used.
 
I'm not certain but I think there are a few different mounting arrangements on various years of X, and with differing options (eg. with AC or SMOG pump). And they have different alternators to match the mounts. So look carefully to see if all of the tabs are in the right place, the gaps are the same width, the adjustment and bolt tabs are the same, etc. I'm sure others here will know exactly what fits what.

I considered the GM conversion when I thought my alt was bad. Mostly because I already have a new GM unit sitting in my storage. However my AC-equipped X has a very different mount and the GM unit was not a good match. But then I discovered I only needed to replace the regulator pack (about $10), so I just did that and everything is good.
 
I would imagine the AC could complicate things. On my 74, the air pump was run by a toothed belt connected to the cam pulley which had a separate narrow track for the air pump belt. Looking at my setup, I think a 79 non AC alternator would likely work.
 
Ya, I know from experience the AC alternator has a very different mount. Even the water pump housing is different where the alt attaches. The tabs and bosses are reversed; outside vs inside of one another compared to a non-AC mount.
 
The remanufactured units at the auto parts stores seem to get bad reviews of people saying they last 2 weeks or had to get 4 of them replaced within a month. Midwest Bayless has the exact replacement alternator I need but for a much higher price than a remanufactured unit. My local rebuild shop charges almost twice the price of the direct replacement alternator to rebuild it.

Looks like my choice is to get the MW replacement. My only concern would be the low amps but I'm not running any extra things anyway, my audio system is my exhaust ;)
 
Not sure if this will help but on my 78 X I was showing charging issues. Some times it would share well and other times not.I changed the external regulator, I had the alternator overhauled and eventually bought a new alternator. Still nothing. I appear to have resolved this by replacing the cable from the alternator back to the starter with a much larger cable. Fixed immediately. Good luck.
 
Peter Cecil said:
Not sure if this will help but on my 78 X I was showing charging issues. Some times it would share well and other times not.I changed the external regulator, I had the alternator overhauled and eventually bought a new alternator. Still nothing. I appear to have resolved this by replacing the cable from the alternator back to the starter with a much larger cable. Fixed immediately. Good luck.
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Yes, that cable is very critical as it essentially connects the alternator output to the rest of the car. It is a good idea to make sure the terminals are cleaned of dirt and oxidation on each end.

An easy check for theartur2000 might be the following:

1. Check voltage from alternator output terminal to ground with engine running. If out of spec, probably the alternator or regulator or a really loose belt.
2. Check voltage drop from alternator output to starter connection with engine running. Don't know exactly what gauge the wire is, but probably at least #10. That stuff is about .001 ohms/ft. I would guess that wire is under 10 ft, so let's say .01 ohms. If the alternator is at full output (probably is not), you would get V = .01 * 45 = .45V. If you are seeing more than that, there is likely a problem. A #8 wire would result in about .3 volts.
3. You should probably do a similar exercise for the wire between the starter and the battery.
 
Might have some news! I'm in my garage right now trying to pull off the alternator and noticed something. You can spin the alternator with just your hands with the belt still hooked up. I don't think that's supposed to happen.
 
theartur2000 said:
Might have some news! I'm in my garage right now trying to pull off the alternator and noticed something. You can spin the alternator with just your hands with the belt still hooked up. I don't think that's supposed to happen.
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That is not supposed to happen unless you are strong enough to also spin the water pump, and crankshaft. Try tightening the belt and check the output.
 
I'll echo some earlier comments:

Although the parts store diagnosis said your cables are good, it is a well known fact the standard cable (Fiat factory size) from the alt to the starter is not sufficient. A heavier gauge cable is necessary for proper function. That is an excellent upgrade regardless of all other issues - and it might solve your problem. To almost the same extent is the cable from the battery to the starter. That connects the other half of the charging system together. So upgrading it is also a great idea (although it is a long one and a bit more difficult to do).

Proper tension on the belt is necessary. The fact it was loose suggests there may be other minor maintenance issues??? Not suggesting anything on your part. But things like all of the connections do become contaminated and highly affect the charging system's function. Remove, thoroughly clean with a wire brush and solvant, then tighten all cable ends, all starter wires, all alternator wires, all of the ground connections, etc.

The indicator light and charge gauge on the dash are not reliable sources of the system's health. Unfortunately this is another of the many weak areas on Fiats. Do not go by what they say. Check all of the charge levels with a decent multimeter at the various locations as suggested already.

IF (I'll repeat) if all of this is done properly and the tests with a multimeter still indicate you have insufficient charging, then - and only then - consider replacing the alternator. At that point you can weigh the cost options. I know what you mean about poor reviews for chain store rebuilt units. But if your budget is limited it may be a decent option. Worst case scenario you get your money back and do something else. Personally I've used a couple of them in the past with excellent results. But I can't assure you if that will happen again or not. Also look for another rebuilder to see what price they offer. Even if it is the same as other options, in my opinion it is a better choice. But all of this should only be after you have thoroughly exhausted all other possibilities. Again, no offense intended, but if you just now discovered the fan belt wasn't working then I don't think you have properly diagnosed the problem and could be throwing away your money by buying replacement parts. I mean all of this with good intentions to help you.
 
theartur2000 said:
12.3 volts
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That's a couple of volts low unless there is a heavy load on the system like trying to charge a dead battery. I'm guessing that is not the case since you got the car started. I would be suspicious of the regulator or the wiring and connectors between it and the alternator. While it could be a bad alternator, the fact that the output is at 12.3 may indicate the regulator is bad or set to too low a voltage. The old mechanical regulators had a little adjustment screw you could use to set the voltage but I doubt the electronic ones are adjustable. If that regulator was not specifically designed for that alternator, it could also cause a problem.

A couple more measurements could also tell you a few things:

Check the battery voltage with the motor running and all accessories off:
1. If it is less than the 12.3 volts at the alternator output, it tells you that the alternator is supplying current so it could be just the regulator.
2. If it is equal to 12.3 volts, it indicates the alternator isn't supplying current so it could be a bad alternator and/or regulator.
3. If it is more than 12.3 volts, it indicates the battery and not the alternator may be providing the current to run the car so it could be a bad alternator and/or regulator.
 
The voltage regulator that came with the car that when I bought it was an Elecman FIA12-1, and I got a new one after being told that it was bad. The problem is the same whether I'm using the brand new regulator or the old one.

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I also feel like it is a wiring problem but the auto electric workshop I was at said that "all wiring to alternator and regulator looks good" he also said "verified correct key power, ground signal, and battery power to both alternator and regulator."

I should also clarify that I went to both an auto parts store and an auto electric workshop, with the parts store saying it was the regulator, and the workshop saying it was both.

The volts are the same both at the battery and at the alternator.

This is just a guess but could it be that the alternator is not getting excited? How would I test for that?
 
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