Pesto's first drive = electric mystry

[70spider]

Well it has been awhile since I last posted. A quick update: after rebuilding the engine, brakes, and drive line I finally got to go for the first ride to break in the motor. At first everything was fine, I was just driving in our small town for about 10 minutes when all of a sudden I lost all my gauges (Tach., Water Temp., Oil Pressure, Fuel, break lights and turn signals) the car continued to run well, but I cut short the break in. I was wondering if anyone may have any suggestions. Thanks.
Update: I have been reading through some older posts and another member had a similar issue and it turned out to be his new 95 amp alternator. I also just replaced my alternator with a 95 amp one, I will put the old one back on and see what happens.

[spider2081]

A 1970 Spiders ignition switch would have the connections right at the back of the ignition switch and they should be push on "spade" type connectors. Its common for this type of connector to loose its tension and become intermittent over time. Checking there for a loose connection might be a place to start. Does your car have an original Sipea ignition switch??
Have you cleaned and retentioned the fuse panel contacts. Also I like to replace the original lead fuses with the newer brass ones. They are stronger and are made of a material more similar to the fuse box contacts.

[TX82FIAT]

Was it just the gauges? Did you test other systems like the headlights. I would do some testing, cleaning, connections review and fuse review before pulling the new alternator out. What are volts at the battery when engine off and then when car is running. It may be as simple as a blown fuse because the new alternator is putting more amps thought an older circuit. I don't think putting the old alternator in will solve the issue. Also, if it is related to higher amps in the circuit you will need to fix the circuit either way with a new or old alternator.

[70spider]

The other systems seem to be fine, headlights and the blower fan work. I will go through the fuses next and I will check the grounds. The ignition switch is the original and when I purchased the car I went through it replacing the lose connections. I'll have more time tomorrow to do a better job of going through the usual suspects. By the way the new alternator is putting out 14.5 volts @ 1500 rpms. Thanks for the input.

[TheBender]

Start simple and work towards the tough stuff. I had the same problem on my 78. Loose/bad connection on a fuse. Pulled over and put new fuse in and it worked. Ended up replacing the fuse box instead of cleaning up that one.

[TX82FIAT]

Methodical process will solve the problem. 14.5 at 1500 RMP sounds about right. My 95 amp alternator is almost always self regulated in the 14.1 area going up or down .2 based on RPM's. Almost all modern cars put up to 14+ volts. I suspect you have a resistance issue creating lower amps than required to operate the circuit. A few Ohms of added resistance can significantly decrease amps below instrument required operating levels. These factory wiring looms have been known to have wire casing wear out, hell we even have metal holding them to the frame that can create a hot to ground blowing fuses over time. A few years back I had to take the dash out and trace wires. I do not know if it was done at the factory or by a prior owner but there was a metal wire punched through the factory wiring loom holding it to the support under the dash. Operated for years that way until it did not. All of a sudden blown fuses until wire clean up and insulate.

[70spider]

Update, with history being the bases of my approach, the first thing I thought was catastrophic. But, with a red face it turned out I just blew a fuse. But my question is what was the reason for the fuse to blow? I took my gauge cluster out and looked everything over, as much of it I could see, and it all seems fine. I was wondering if my old car can not handle the higher amps the new alternator puts out? If so, would it be best to go to a 65 amp alternator? The only reason why I upgraded to the higher output alternator was so the wipers would work a bit better and the lights brighter. I do not have a stereo or fog lights, nor do I plan to get them. Well thanks for the help, It is raining now so the next drive will have to wait. Have a great day.

[redcars]

It doesn't matter what amps the altinator puts out as long as it is enough. The car only uses what it needs. The reason for the new altinator is higher volts. The higher volts is what makes everything work better. The altinator is not your problem and old fuses some times just blow.

[spider2081]

The reason for the new altinator is higher volts.

The new alternators are often regulated at a slightly higher voltage than the stock alternators. Yes it makes the wipers work faster and lights burn brighter. That being said it also causes most all the loads it operates to draw a higher current. Ohms law I=E/R. A brake light bulb that draws 2 amps at 13.2 volts will draw about 2.2 amps at 14.5 volts. Doesn't seem like much change but there are probably a number of circuits being protected by the fuse that blew. The total increase in current contributed to the failure. Also the increased operating Volts/current can shorten the life of bulbs and other electric devices. They are simply working harder.
Fuses, like incandescent light bulbs filaments flex each time the circuit is activated and de activated. In time they can fail from use.
I like to replace all the fuses with new, choosing a brand that uses brass instead of lead. They are otherwise the same value and type. This reduces age failures and dissimilar metal corrosion.
Not knowing which fuse blew a suspect could be the power wire to the back-up light switch. The are prone to breaking and shorting out intermittently.

[TX82FIAT]

Great point about the slightly increased amps from the higher volts. An older fuse might just give way under the slightly increased current. For the wiper motor, pulling the cowl and cleaning/lubing the mechanism really well will help the speed of the wipers more than the alternator. For the headlights there is a relay that will brighten the lights even more and prolong the life of you ignition switch.

[70spider]

In response to the fuses, after purchase of the car I changed all the fuses with Flosser brass fuses which was in March 2014, so they are a little over 4 years old, only 2 of which he has been running , and this was the first one to blow. When the weather gets a bit better here and I do a better job at bleeding the brakes I'll go for another drive and see what happens to the fuse.
Ok, about the wiper motor, dumb question; how do you remove the cowl to get to the motor? Plus I did install the headlight relay kit, It does do a great job along with new headlights.
So with what you have been telling me is that my expectations on this 95amp alternator were a bit unwise and that perhaps the old alternator is best.

[JohnMc]

Just remove the six Phillips screws around the edge of the cowling and the windshield wiper motor etc will come right out. There will be the electrical connection that you can disconnect along with the windshield washer squirters tubing that needs to be removed before actually removing cowling.

[JohnMc]

I had a 95 then went with a 65 amp just because it "fit" better. The 95 came with a ton of washers and i could not get everything lined up right - and also had issues with the studs or bolts (cannot remember which). It should have had lockwashers, IMHO, and had some locktight - and came loose. I would presume in the 3 or so years since I had bought it they got it right.

[JohnMc]

I had a 95 then went with a 65 amp just because it "fit" better. The 95 came with a ton of washers and i could not get everything lined up right - and also had issues with the studs or bolts (cannot remember which). It should have had lockwashers, IMHO, and had some locktight - and came loose. I would presume in the 3 or so years since I had bought it they got it right.

[DieselSpider]

A device that draws 2 Amps at 13.2 Volts is a 26.4 Watt device. Watts divided by Volts = Amps so the higher the Voltage the lower the Amperage drawn. A 26.4 Watt device at 14.5 Volts is going to draw 1.82069 Amps.

An intermittent dead short on the other hand is going to draw to the max capacity of the Battery/Alternator or Wiring. Wiper linkage that is binding could also be part of the problem. Best course before upgrading alternators is the fix the root cause of the slow wipers and dim lights which will be wiper linkage that needs lubricating, commutators loaded up with carbon from the brushes, corroded or failing wiring/connections or switch gear. These problems will still be there after upgrading the alternator and will continue to degrade to the point of total failure if you do not fix them. In the case of an intermittent short the event will be much more dramatic with the more fully charged battery and higher voltage/amperage available.