Originally Posted by ALLAN WARD
We are currently anchored in a remote
river in Brazil
with a strange problem.
We were having dinner this evening when all of a sudden our Perkins
Prima M50 starter motor started spinning without engaging the solenoid or that is what we presume is happening . I quickly cut the power supply by turning off off the master switch as there was a burning smell coming from the engine compartment at the same time . Everytime we switch on power the starter motor spins freely without engaging the solenoid .
Bear in mind that this takes place with the ignition switched off and no pressing of starter buttons .
Our problem obviously is that we cannot negoitiate the river entrance without an engine so we are pretty stranded right now until we are able to remedy this problem . Please help .
Power to the starter motor is supplied directly from the batteries and is only disconnected by the battery
switch. A power lead then comes off the positive terminal to the ignition (starter button) switch at the engine panel which when activated provides power to the solenoid on the starter. this is then supposed to engage the bendex and also close the contact internally to the starter motor itself.
the starter motor requires replacing or rebuilding but good luck finding anywhere to get it repaired where you are.
The only suggestion(s) that I can make are
1 - with the battery switch open or off remove the negative terminal from the starter (I can't remember if they are wired this way as some starters are grounded through the case) which will prevent the starter from turning. Close the battery switch (on) and the starter should not turn. Don't confuse this lead with the main negative lead from the battery which should be connected to the engine block. Depress the ignition switch on the engine control panel
and you should hear the bendex engage (you might have to listen closely near the starter to hear this. If the bendex engages have a second person then touch the negative cable from the starter to the engine block where it was connected before or anywhere else that provides a good contact on the block. Careful as the will be a large current
draw and sparks will fly.
2 - If I remember correctly the solenoid on these perkins starter is internal not external which is a problem in this situation as you cannot disconnect the positive lead from the starter separately from the solenoid itself. The only other thing that I can think of would be to have someone standing by at the main engine panel with the ignition switch on and holding the starter button and then turn the battery switch on. What should happen is that the solenoid engages at the same time the starter motor starts to turn which is what normally happens when you push the starter button. When the engine starts let go of the starter button and the bendex should disengage however the starter motor will likely keep on turning. You would then have to be able to remove the main power cable from the starter itself to stop the motor from turning. I am not sure at this point whether you could just shut off the battery switch as power would be being supplied from the alternator
as well. I do not believe that it would make any difference at this point whether the starter kept turning as long as the solenoid was no longer engaged. Might completely screw the starter but if there is no other way. You could also disconnect the field or exciter wire from the alternator
and that way turning off the battery switch would cut power to the starter motor for sure. Option 2 may be the better way as it would certainly be safer than laying alongside the engine while it was turning.
With the battery switch off and the alternator disconnected you would not have any gauges and you would have to shut the engine down manually at the stop solenoid (usually painted red on the injector pump). Marine
engines are designed to not require power to keep them running as opposed to most other land based diesels that require power to keep the fuel
can you post your wiring
You might also try tapping the starter with a hammer or other heavy metal object but I doubt that this will work with this starter.
I learned this lesson the hard way while in Thailand
and now always have a spare starter on board.
Good luck and keep us posted.