Posted by Steve on Tuesday, November 20, 2007 at 16:58:36 :
In Reply to: Re: OT electrical question(positive ground) posted by Kevin in Ohio on Monday, November 19, 2007 at 23:37:28 :
Hey Kevin,
Wasn't meant as a slam, just don't think it's possible as described.
The starter is a dc motor and as such will rotate backwards if the cable are reversed. Not sometimes, but all of the time. Since the bendix is designed to only engage in one direction, how was it spinning the engine?
The engine's moving parts can be run either way by reversing the connecting rods and installing a reverse ground camshaft. Chrysler used to do this in their marine engines to achieve counter rotation when using twin screws in boats...
But, without the cam being reversed, you would have the exhaust valves opening first then followed by the fuel injection, followed by the intake valves opening.
The engine management electronics would absolutely not work with the polarity reversed. Very often the circuits actually have a safety diode that is designed to blow and create a direct short so it doesn't ruin the rest of the circuit.
Lastly, the fuel pump issue that I brought up before. The pump also contains a DC motor and running backwards would want to pump fuel from the engine to the tank not the other way around.
Again, didn't mean it as a slam, just can't see how it would work technically.
Pretty much everything else in the truck would just not work (radio and digital gauges) or run backwards (heater). Lights wouldn't be affected.
Just my $.02...
Best,
Steve
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