4.3L Merc Alpha LX - starter won't disenagage

[dmuenke]

I've replaced battery, ignition switch, starter & starter solenoid....engine starts, but won't when ignition key to off position...instead, starter shaft keeps turning with running engine...thought it might be slave solenoid, but followed Merc's manual by performing slave solenoid test using jump wires from battery to slave (which made engine crank - is that right???), and put continuity meter on posts....doing that gave me meter movement which Merc says indicates slave ok....I'm out of ideas now - should I just replace the slave anyway???

 

[Silvertip]

Re: 4.3L Merc Alpha LX - starter won't disenagage

You replaced the ignition switch because why????? You say the engine starts but won't when ignition key to OFF. (Won't what ??). Why are you jumping the starter if it continuously runs? Or are we dealing with more than one problem? I'm going to guess that you have some wires incorrectly connected at the ignition switch. If you are saying the engine won't shut off, that points to an ignition switch problem. If the starter stays running that can also be an ignition switch problem, especially since you replaced the starter and solenoid. Re-check the ignition switch wiring and make sure you have the correct switch for this application.

 

[Texasmark]

Re: 4.3L Merc Alpha LX - starter won't disenagage

Other problem could be mechanical binding of the starter shaft, gear, or bendix. I have had similar problems. Lube is visable, but has lost it's lubricity. A little cleanup and regreasing did the trick.<br /><br /> Might take a voltmeter and see if the starter is getting voltage when it's stuck to the running engine. That would clear up any electrical supply issues.<br /><br />You can also check power to the starting solenoid small terminals. Should only be 12v when you put key in START position.<br /><br />I have also had the high current contact of starter solenoids stick shut which would do as you mentioned. If you have voltage at the starter, but no voltage at the small "operate" terminal(s) on the solenoid (when it is hung up), the internal contact of the solenoid stuck....caused by welding when the high current goes thru it to start the engine.<br /><br />May get a little voltage from the starter acting like a generator with it's armature turning by the action of the motor.<br /><br />HTH<br /><br />Mark

 

[Texasmark]

Re: 4.3L Merc Alpha LX - starter won't disenagage

Missed something. Just noticed that you are dealing with an auto engine. In addition to what I said, you might loosen the mounting bolts and attempt to reposition the starter. I'd loosen it up so that the case can move and hit the starter a few times (do not start it, just a bump) and bolt her back down. Might do it.<br /><br />Good Luck,<br /><br />Mark

 

[dmuenke]

Re: 4.3L Merc Alpha LX - starter won't disenagage

Thanks TexasMark...just a rundown of the events as they occurred; while boating off & on all week I niticed one day the starter wouldn't disengage from engine while it was running - didn't get it off in time and starter burned up; I replaced the ignition switch and start & soleniod, along with 12V start battery; engine starts right up but starter still won't disengage; I found Mercruiser shop manual which suggested the "slave solenoid" might be stuck; I replaced tested it for continuity as per the manual, and the meter registered 000; I replaced the slave solenoid, which I also tested for continuity in the same way and the meter moved nicely (to about 7); figured I found my problem - BUT - same problem exists!....I'm out of ideas now...any thoughts?....boating can be real drag....is it time to spend the big bucks and take the boat in to e mechanic?

 

[Silvertip]

Re: 4.3L Merc Alpha LX - starter won't disenagage

The only things that can allow the starter to remain engaged are 1) incorrect ignition switch wiring, 2) defective ignition switch, 3) sticking starter solenoid due to incorrect installation (mechanical linkage binding), 4) slave remaining activated due to wiring problem or defective slave. If you are confident that the positive shifting linkage on the starter is working freely, then an electrical problem is allowing the starter solenoid to remain engaged. Rig up a test light to the output terminal on the starter solenoid (starter side). Start the engine. If the test light remains on after the key is released you have an electrical problem. If the light goes out but the starter remains engaged you have a mechanical problem. Did you not mention earlier that the engine wouldn't turn off after being started? That would imply you have a wiring problem at the ignition switch or there is a harness problem.

 

[Texasmark]

Re: 4.3L Merc Alpha LX - starter won't disenagage

Remove the starter from the flywheel. Best thing to do (best way to do that), if you have room, is to get longer mounting bolts (talking from process not actuality as I am not looking at your engine) and put 3 or 4 washers on the bolts between the starter and engine block. Just enough to keep the teeth of the starter gear from being able to engage the flywheel ring gear.<br /><br />Hit the switch like you were going to start the engine. The armature should spin the bendix up into the position where it would contact the flywheel very smartly. Then immediately release the start switch and the starter gear on the starter should return to it's rest position adjacent to the starter body. <br /><br />As we have mentioned, you either have mechanical binding or electrical power long after you want it. This test will tell you right quick. If you pass this test, try it several times and see if it functions properly.<br /><br />If so, your starting gear is jamming against the flywheel (causing it to hang) and a couple of shims between the starter and the engine block should fix you right up. Now, why did it just start doing this? Dunno.<br /><br />Post back on your progress.<br /><br />Mark