I think my starter died

I am pretty sure I know what the problem is but I didn't think it would hurt to post it on here just to run it buy a few other ppl and get some oppinions. I just went out to start my 87 XJ 4.0 (it has the Mitsubishi starter motor that came on the Renix 4.0s, mine was rebuilt with a few peices out of a starter from a 90, possibly the brushes but I can't remember). I went to start it today, it cranked over maybe 2 or 3 times (you all know how the Renix takes about 4-5 cranks before it starts, somthing to do with the smaller ground wire it has IIRC) on what should have been the 4th turn over it made a shuddering noise and then followed by a high pitched ZZZZZZZZZZZZZ. What I think is going on is that my solinoid on the starter motor just gave up the ghost and that ZZZZZZ sound is the pinion gear just spinning around inside the starter since the solinoid isn't there to push it into the flywheel. Now I tried it a few more times, got that shudder maybe twice more out of it. It hasn't made any kind of heavy duty grinding noises but I figured I would stop just incase because I don't want to damage my flywheel. I can remember a while back I got somthing like this where the starter wouldn't work but once we took it out, it bench tested fine and when reinstalled it worked. I was just wondering if anyone has any advice for what else could cause this (I was also thinking maybe the starter solinoid up top (the one by the battery) blew up but if I had to I would put my money on the one thats on the starter.

Start solenoid, most likely. The one by the battery is the "Start Relay," and it is what feeds the current to the solenoid. Then, the solenoid feeds the current to the starter - if your starter is cranking, the relay is most likely good. Generally, you don't get anything when that relay goes (I went through four of them one summer...)

I would probably save trouble and have a shop rebuild the starter - you may miss something that they wouldn't, and that will save you trouble. The starters were the same for a good long while (up until 1999 or so, I think,) so the later brushes and such in your early starter won't be presenting a problem.

By the by, the RENIX crank times are long because the ECU won't fire the ignition or fuel injection until it sees 300 rpm at the crankshaft position sensor, and it wants a valid SYNC pulse from the distributor. It can start without the SYNC pulse, but it will not start without the CPS signal! Upgrading your mains has been known to help with that, since they will allow more current to flow to the starter, and therefore the starter will "spin up" faster. It's not just the "ground wire being small" - that's a contributing factor, but the starter uses the mains ground from the engine to the battery. The problem from that arises when the firewall ground strap gets dirty, since that completes the ground loop for the sensors to the ECU. That little strap is known as the RENIX Killer - and can cause all sorts of trouble.

Reports from the field on upgrading mains have been consistently good - I've gotten plenty from people who have bought mine. However, I don't think that's the problem you're having right now...

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Ok so I have my starer motor on the bench now with the battery charger hooked up to it and from what I can see it looks like its working. The only thing is and this might just be my own ineptitude but, I can get the solinoid to engage the pinnion gear, and I can get the starter motor to spin over, but I can't get it to do both, I can't get the solinoid do engage and then spin the starter. I can remember it doing this before, wouldn't start and when I took it off, it tested fine, put it back in and it worked. Could this be caused by the starter relay? I was thinking that but if the relay was toast wouldn't it cause the starter not to work at all? The starter is turning, its just the solinoid is not engaging the Pinnion into the fly wheel.

well I just tried the starter again in the jeep, still no luck. I was reading in one of my books that the clutch in the starter motor could be shot, causing it not to work, but my only worry is that the solinoid does not engage at all. No click when I got to start just ZZZZZZZZZ.

The way it's supposed to work is that the start solenoid is a larger version of the start relay, using the plunger on the starter as a part of the relay.

There are contacts at the bottom of the "can" that are pressed together by the plunger being drawn into the barrel of the solenoid (usually - I'm talking generalities here. I've torn down more Delco starters than I care to think about...)

So, the plunger is first drawn into the solenoid barrel, then power is supplied to the starter armature and field windings. So, a failed start solenoid is usually indicated by the key going "click." Since the solenoid draws, typically, 10-15A, some sort of relay is used - which is why the thing still goes click - that's the relay.

Some designers spin the starter pinion gear, which (theoretically) makes it easier to mesh the pinion with the ring gear on the flywheel. This would be why a starter would spin without extending the pinion - which is what we seem to be running into. I haven't torn down a Mitsu solenoid yet to see how that works.

If you've replaced the solenoid, there may be some mechanical interference between the solenoid barrel and the start motor plunger - I've run into that before. Clean the start motor plunger with crocus or emery cloth and wipe clean with denatured alcohol (or similar - do not use water!) and check the solenoid barrel.

Also, bear in mind that most battery chargers just can't supply enough power to turn the start motor properly - better to use a battery and jumper cables. Even at "no-load," the start motor's current draw is rather high.

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