RV won't start, have replaced starter & battery....?

Question

My 1975 Dodge M-500 Chassis motorhome, powered by a 440, won't start.

I already put in a new battery, and a new starter, new starter relay, and still have the same problem:

When the ignition is turned, the starter engages, and you can hear a rapid, percussive clicking, like an impact wrench type of sound, but the engine doesn't actually crank...like the starter gears aren't quite meshing with the flywheel.

One piece of info: When I put the new battery, I accidently hooked it up backwards, and saw a puff of smoke around the area of the alternator. Strangely, with the battery hooked up backwards, the engine cranked, strong! Now that the battery is connected correctly, however, I'm back to square one...just the rapid-fire clicking, no engine crank. If I shorted out the alternator, would that account for the starter problem?
Is there a way to test this?
Are there other components that likely would have been shorted out by the battery being backwards?

Answer 1

The starter sounds like it needs shims to mess with the flywheel. the no start pull the distribetor cap see when you crank if the rotor turns, the puff of smoke you could have cooked the altenater and the distibetor. good luck your going to need it.

Answer 2

I know you PROBABLY did this already, but do it again. Any chance the battery cables from the relay to the starter are not secure? Is the cable from the battery to the relay tight? Are all the ground cables secure?
It sounds to me like the starter is getting voltage, but not enough current to crank.
I don't think that the reversing the polarity did anything to the starting system, but you very well MAY have cooked your alternator. Those diode bridges don't really like that high a current flow.
But you should be able to crank the engine even without an alternator .
If all the connections are tight, then the only other thing I could recommend you do is to go right to the starter and jump the large wire (battery cable) to the small terminal and see if it will turn over then. If it does, there is a problem in the control circuit.
If it still wont turn over, put a volt meter on the battery while you try to crank it.
It should not drop below 10 volts.
If you are using a digital volt meter, check the static battery voltage.
If you have a charge of 12.5 volts or better, battery is charged.
If the voltage is 12.25 volts, the battery is only 1/2 charged. If the voltage is less than 12.1, consider it dead and needs a recharge.
These numbers do not apply if you are using an analog meter. The meter won't be accurate enough to give you a clear indication of the battery's condition.

Good Luck

Answer 3

Check for bad ground connections. That may explain your "puff of smoke". As, the power would create a spark when jumping around the coroded or broken area in the connection.

As for the "impact wrench sound", get out your trusty Haynes or other manual and follow the wire paths for your starter and starter relay. You may have it wired incorrectly.

Answer 4

check the battery cables for corrosion and check the negative cable where it hooks up to the block or ground point on engine then maybe check the wire on the stater that should have 12 volts when in crank position