I agree with that mickmate. I learned that lesson with my Kirkham - the
fans nearly killed the battery one of the first times I drove it. Now I just
hit the battery kill switch after I shut it off - no more problems. Nothing
else I ever drove in the past had that feature and I usually got close to
200k miles and they were still running fine when I sold them. Never got
too hot anyway.

Msd
 

Digital Fluke shows about 350 ma from battery to MSD with switched lead off.
Maybe I have a bad 6AL but this is the second box and it still does it.

In regards to the eletric cooling fan....don't most new production cars have electric fans that can run at any time?

I have a thermostat probe in the radiator that comes on at about 190F + or -

I have cast iron heads that I understand continue to transfer heat once the engine is shut off....my water temp guage goes up when the engine is off for a few minutes and fan is not running

looking forward to hearing your thoughts

John

I disagree with the MSD theory. The small "Switched" 12 volt wire is what initiates current draw within the unit. I would look at the voltage regulator or a tired battery with bad cell(s).

I am running a 1 wire GM alternator and at first I had the "excite" wire hooked to a constant power source and sure enough my battery was dead every 4th or 5th day. Finaly hooked it to a switched source and problem solved.

Hi John,

All good suggestions here, we have all had our share of electrical gremlins.

What kind of Cobra do you have.....I had a problem with my Shelby and it was really tough to find. Ended up being the red light on the dash board above the ignition switch which ends up being a resistor in the charging circuit for the alternator, when the red light comes on before you hit the starter that current flows to the alternator and provides the exciter circuit.

The light is spring loaded and there was a washer around the mounting that gave it an intermitant open, the car would start and run on the battery until it was dead sometimes. If you put a jumper on it it would start and the battery would charge ---- Sometimes. As I said it was a devil to find, removed the washer and all was well.

Tony R.

The cars that come equipped with electric fans are run by thermostat/computer. Most cars have 2 electric fans for a reason. One is run strictly by the engine temperature and the other is also run by engine temp, but also has an override that switches it on and keeps it on as long as you have the A/C on....With the A/C on, you always have one fan running and the other will cycle on/off according to the water temp........they both will shut off when you turn the ignition switch off.

Regardless of the heads,be they aluminum or iron, once you shut off a fully warmed up engine, your water temp gauge will show some increase in temp, mine usually about 5 to 8 degrees over the running engine temp, that's normal, running you fan with the engine off does nothing but cool the water in the radiator, does nothing for the water in the engine itself and will not cool the engine, to do that, you would have to be circulating the water thru the engine via. electric water pump......

David

Yeah, I had the same issue. I wired the Alternator wrong. Turns out the one-wire alternator needed like 3 wires (can't remember) and I ran a seperate ground wire just to make me feel better. One of my employees fixed it under 30 minutes.

Live and learn.

The ERA is designed for the fan to run regardless of whether the ignition switch is on and the temperature in the bottom hose (where the thermo-switch is located) is above 175F. The fan will typically shut off after a couple of minutes if it is running when the car is shut off, which indicates that when the thermostat is open, there is some thermo-siphon action going on. That small flow (encouraged by the fan-cooled air in the radiator) keeps hot spots from forming in the block and heads. Therefore, post-shutdown boil-over is less likely.

Running the fan is also a small attempt to cool the engine compartment a bit after shutdown, which might help prevent fuel percolation during heat soak. Imperfect, but it might help a little. Running the fan for a couple of minutes is not a significant draw on the battery unless something else is wrong.

A simple test is to dissconnect the battery after charging and let it sit overnight and then reconnect to see if the battery held that charge, or has an internal short.
When I bought my car in Remo (August) It had a master switch mounted on the firewall accessoable from under the dash. It was a little awkward (impossible) to get to after belting in. I often negelected to turn off that master switch when running errands, either from forgetting or, expecting to be only a minute. After leaving the car the hot water would collect at the top of the engine and radiator (where the thermo sensors for the electric fans are) and turn on the fans (4). The fans didn't make so much noise that you could hear them from any distance. I'd return to the car after more time than I"d planned on and find the battery drained. If Iwas lucky enough to have enough battery to get the electric fuel pump to click a few times and any incline, I could get the car to roll and dump the clutch and start. Some times It didn't work. I tried a Battery Brain, a automatic battery disconnect switch that mounted to the battery and was supposed to dissconnect the battery automatically. I'd have it turned on to the manuall position or something and it didn't work. Then finally it quit working completely( I was actually sitting in the car in the street, engine turned off, talking to a COP and didn't notice the fans running. My fix was I mounted another master switch from Flaming River on the dash in series with that original master switch and within reach while belted in. Twist the red knob on and just bump it and it turns off.
I do not have MSD I have Mallory. There are two power wires one(switched) and another power on allways on (not switched) for the MEMORY. Different power draws. If your system is similar, make sure that the electrician didn't put them together to make it easy for himself.

An MSD box has a capacitor in it. Once that capacitor is charged, the box draws about the same amount of power as a radio does for the memory station presets....

Hello All

It appears from all of the posts that this is a common situation that might involve the MSD

I do understand that the fan running after shutdown is mostly to cool off the engine bay and possibly prevent vapor lock etc. I some how feel better getting the heat out of the engine bay

My car is an Antique and Collectable brand. I want to look at the alternator again and its associated wiring.

Does anyone have the a wiring design for the alternator that can be e-mailed showing both the Ford wiring schematic and the GM "1 wire" style?

thanks

John

There's a section on the Ford alternator here.