Battery or Alternator?

[70spider]

I have this intermittent issue with the car not wanting to start every now and then. I jump it and it runs fine for a day or two then it won’t start so I jump it and it runs fine. I finally broke down and purchased a digital multimeter, I couldn't figure out the analog one, so here is what happened:
Battery pre start (not running) = 12.4V
Initial reading @ idle = 14.2V
After I put a load on the system (lights) @ idle = 12.4V
I then turned the lights off and took another reading @ idle = 12.4V
Then while doing the readings the cooling fan came on and the reading was 12.4V
So is it safe to assume it is the alternator?

[81SPIDERMATT]

took my car to autozone (I think) they hooked up a gizmo that will isolate problem between battery alternator or regulator ..... turned out to be the regulator ..... same symptoms as yours .... the regulator was an easy and cheaper fix than the alternator .... my limited abilities and use of the multimeter pointed to the alternator ..... glad I went and did the free diagnostic .... Matt

[70spider]

Well I redid the procedure but increased the rpms from idle to 2k.
Battery pre start (not running) = 12.7V
Initial reading @ idle = 13.4V
After I put a load on the system (lights) @ idle = 13.4V
Turned off lights @idle =13.4V
@~2000rpms = 14.3V
Lights on @ ~2000rpms = 14.2V
Then again @ idle no load = 13.4V
According to these results evrything is "A-OK" ,I am going to rip my hair out .
Any suggestions?
I think I'll appraoch this like I did the cooling system, everything new .

I was looking at this as a replacement alternator, http://www.vickauto.com/newstore/index. ... ts_id=4261 . With all the horror stories of poor quality remanufactures units I thouhgt this would be a good alternative. Plus if I get a reman. unit and new voltage regulator I am looking $150+ and the 95amp unit is $190 + $50 (mounting bracket) so this is my least expensive option.

[baltobernie]

Yes, according to those results, everything is OK. Might be an intermittent ignition switch; a little corrosion on the contacts after sitting for a few days? If you can bypass the switch at the next occurrence, that would be a diagnosis. Of course you've checked the battery connections and gave all the fuses a spin, but you might also try removing the positive battery cable, and placing your multimeter in series with the battery, and observe the current draw (if any), with the key Off. Your multimeter has the ability perhaps to only measure up to half an ampere, but there should be only a few mA showing for the clock. Otherwise, there is a drain somewhere.

If you are intent on pulling your hair out, send me some ... I could use it

[azruss]

I'm with Bernie on this. alternator and battery are ok. I suspect the culprit is weak electrical connections. battery to starter, battery to ground, alt. connections, ignition key connections. clean fuse contacts. could be your starter solenoid as well.

[70spider]

I'm with Bernie on this. alternator and battery are ok. I suspect the culprit is weak electrical connections. battery to starter, battery to ground, alt. connections, ignition key connections.

When it doesn't start a simple boost to the battery starts it everytime,this is why I am perplexed. If it was a lose or corroded connections would it still start with the battery boost?
When it does occur I do occasionally here a sound reminiscent of a short from the starter. I'll check there, even though I recently replaced the old starter with the new gear reduction one from AR.

[spider2081]

If you are connecting the jumper cables to the cars battery cables at the battery terminals your problem could be corrosion on the battery posts of the inner surface of the battery cable that mates with the battery post. Putting the jumpers on the cars cables bypasses the cars battery and battery connections. A simple test when the car does not start. Hold the key in the start position for 15-30 seconds then quickly feel the cable terminals on the battery if either of them is warm to the touch it needs to be disassembled and cleaned.

[azruss]

I have seen this issue with fiats over the several decades i have owned one. You have a condition that pops is ugly head up in the low volt situation. This doesn't mean low volts everywhere, just at the starter or ignition switch. Not saying this is the issue, but a plausible explanation. The starter solenoid does a couple of things. It kicks the bendix drive into place and pushes a plate against the top and bottom lugs on the solenoid. On most of our cars, this plate has never been serviced so has dirt, oil and corrosion on it enough so that if a good strong contact isn't made, it won't let enough current pass to turn the starter. Your starter requires more amps than the rest of the car combined. Before i rebuilt my starter, it would start in the morning when it was cool and perhaps a little humidity on this plate. as the car ran and warmed up, all the moisture went away and no starty, starty. This resistance and low volts to the starter make the starter want to swallow more amp, thus demanding more of the battery and the connection points. When you jump the battery, you now have twice the power at your disposal. If the battery is in a running car, then you are hitting your battery with 14+ volts giving it enough juice to override your weak spot. This is why i recommend cleaning up contact points, specifically in the power circuit. The jumping of the battery will stop being effective as what ever is your weak spot gets weaker.

[70spider]

Thanks for the trouble shooting ideas. I checked the connection to the starter it looked clean and was snug, the battery connections are clean. As I mentioned prior the starter is new, less than 3k on it. Your thoughts on corrosion do not fall on deaf ears, I have a suspession the issue may be in the wire from the battery to the starter. When I put new terminals on it it had black brittle sections, so I fear it may run through the whole wire.
Another interesting occurance was when I was checking the voltage @ idle agian the fan came on and the voltage went from 13.5V to 12.5V and stayed there while the fan was on. After the fan cylcle was done the voltage stayed around 12.5V until I increased the rpms then after a few seconds returned to 14.2V. I let the fan cycle back on to see what the voltage was when I increased the rpms to 2k the volts were only 13.4V. The fan takes a lot of juice to run.
On the lighter side, my clock (which was intermittent at best) is now working flawlessly. My wife noted that it must be due to the he fact I completely rebuilt the suspension, I remarked "that's Italian for you".

[81SPIDERMATT]

does a 70 have that pesky pink wire that gets loose and causes same symptoms

[baltobernie]

I have a suspicion the issue may be in the wire from the battery to the starter. When I put new terminals on it it had black brittle sections, so I fear it may run through the whole wire.

I think you're on to something here. That occasional sound you're hearing is probably the result of insufficient current reaching the starter. Some describe the sound as "crying". As I'm sure you know, that cable travels rearward a long way thru a trough along the firewall. Also of course it takes two leads to form a circuit, so a fault in the big ground strap/wire must be ruled out.

Matt, are you talking about the pink wire from the ignition switch; the one for the key buzzer?

[81SPIDERMATT]

no ...it goes to the starter .... hooks to a spade terminal .... cleaned mine and it was like a different starting car .... have no idea where it originates from but remember reading about it and it causing problems .... so when I was having problems exactly like yours broke down in a parking garage in the middle of the night with no hopes of a jump I pulled that wire .... cleaned it and the terminal it went on with my pocket knife and never had the problem since

[azruss]

the spade terminal on the starter solenoid is activated from the ignition switch. This provides power to the solenoid coil. If this is weak, the solenoid will not kick the contact plate hard enough. I'm not convinced that a rebuilt starter means they also rebuilt the solenoid.

[baltobernie]

Wouldn't his new gear-reduction starter have its own (new) solenoid?

[70spider]

Wouldn't his new gear-reduction starter have its own (new) solenoid?

Yes it does, that is why I feel my issue may be the corroded battery to starter cable. I am going to order the new cable Monday. What size should I get, 2 gauge?