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another starting issue

XJin-AZ

NAXJA Forum User
Location
Cottonwood, AZ
89' XJ Larado 4.0 I6 AW4 np242 D30/D35< 225,000 on her


new parts; plugs, wires, rotor, cap, starter, die-electric in a lot of the connections, throttle body pulled and cleaned, and various vacuum lines replaced and ran normal after all of this.

Symptoms; starter will engage for a half second and then retract and continue to spin. I've always had hard starts, long crank, sounds of missing teeth on flexplate (none seen) but it is a little worn on the front edges, so tryed to manualy rotate the crank to a different position and the same happens, no wear what so ever on the starter(new and tested), battery is ok (took over 30 min of cranking and still no sign of goin low). delt with all that for over a year. pulled the cps to look at and the protective coating crumbled away so i have a new one to install. search didnt have any symptoms that i'm having so not sure what i should be checking. Missed 2 days of Rockfest because of this, feeling like i'm :banghead:
 
It sounds like the starter is not working right to me. It could be bad wiring as well. Jeeps are notorious for corroded primary wiring. Sometimes they look fine but are rotted inside. On my ex's TJ the wire from the battery to the starter went bad causing intermittent power lose.
 
Both hot leads (to the starter and to the starter relay) and the ground are 6 months old and upgraded size, the solenoid wire(green) shows continuity and like i said before the starter is new and tested twice now, i will be pulling the inspection cover at lunch today and post a pic of the flex plate
I've also installed new oem motor mounts about 3 weeks ago if that matters at all
 
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Sounds like the starter like the others said. Solenoid weak/Bendix sticking probably. When it was tested, did the Bendix stay out while it was spinning?
 
I had a starter relay that was a giant glob of rust and mud inside. Possible the contacts in the relay get hot and screw up. Try jumping the solenoid wire, dark green, directly to the large lug with the red wires on the starter relay and see what happens. Be a little careful with the bayonet connector it may melt a little.

I also had to replace the solenoid wire once in a later model XJ, it was seriously crispy and the wire under the insulation was breaking, the insulation was way hard. My guess was it partially shorted or drew to many amps at sometime and got hot enough to crisp the wire, but not hot enough to pop the fuse or fusible link.

There is a dark green wire with tracer (stripe) that runs with the dark green solenoid wire. I sure don't remember where it ties in, maybe at the same pole as the solenoid wire (the "S" pole on most starter relays), maybe a splice, maybe different by model year. The dark green wire with tracer, runs to the ECU and triggers the start mode for the computer.

Usually when the starter spins up it forces the starter gear into the flex plate. So my idea my be off base here, but heck it is quick to check.

Is it possible the flex plate is cracked or the bolts are backing out? I've removed the inspection plate on mine before, made me a little pointer out of a piece of coat hanger and bolted it to the bell housing, bent it until it was just making contact with the flex plate, then manually rotated the motor. It will tell you quick how much out of round or runout you have on the flex plate.

Just some ideas.

I've only had two starters that spun up without turning the flexplate on an XJ, one had a bad over running clutch. The over running clutch isn't something that screws up very often, but anything is possible. The other starter that spun but didn't engage was just loose mounting bolts.

I've also seen bent forks, broken forks or forks with a worn pin, though not that I can recall on a XJ starter.
 
Sounds like the starter like the others said. Solenoid weak/Bendix sticking probably. When it was tested, did the Bendix stay out while it was spinning?

yes the bendix did what it was supposed to when tested, i'll run a new solenoid wire this evening for sh!ts and giggles.
heres a pic of my flex-plate
IMG_0552.jpg
[/IMG]
bolts are all tight and no cracks to be seen,
this spot seems to be the worst wear spot on it,
would that cause the teeth of the starter to slip off?
if so,why then when i rotate it manually it still does the same on a spot that looks perfect.
i'll try the coat hanger trick, hope that tells me nothing lol, so do not want to pull that plate
 
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A little hard for me to make out in your picture, but I can see at least some of the flex plate teeth are pointed. The teeth on all I've looked at are kind of flat across the top.
If the starter is actually spinning up good, getting good RPM and the starter gear is actually going all the way to the end of the shaft, tight up against the end bushing/bearing and staying there, it should turn over IMO on the good section of the flex plate and maybe make some horrendous noise and skip on the bad section.

Just throwing some possibilities out there. If one brush is making bad contact, dirt, mud, worn, whatever the starter may turn over slow. Almost like with a weak battery. The spin of the starter helps hold the gear, far into the flex plate gear teeth, along with the forks hooked up to the solenoid that pushes the starter gear (and over running clutch) into the flex plate teeth, I've seen broken, bent and loose starter shift forks on various models of starter. The thread pitch on the starter shaft, spin, the solenoid and fork kind of work together to keep the starter gear in the flex plate teeth. If the rubber seal gets torn (I've seen one come torn from the factory) and water gets into the solenoid piston it can gum up the works with mud and rust.

Just a wild guess, but yours looks like *a* starter (sometime in the past) or *the* starter (the one you have now) may have had severely worn gear teeth. The bushing at the end of the starter can also wear, allowing some side play in the shaft. Or the/a starter was installed with loose bolts.

The most common reason for the pointy teeth and the starter gear missing the flex plate gear, may be, at some time or other, the starter bolts came loose allowing the starter gear to skip over some teeth, BTDT my son tightened (not) the last starter I put in, the bolts came loose and the starter eventually spun without turning over the motor and occasionally made some horrendous noise. Just for fun grab the back of the starter and try to move it sideways, push hard, is it possible you have too long of a mounting bolt in there someplace?

Chevy's are notorious for doing what you describe, haven't seen it so much in Jeeps. The Chevy solution is to shim the starter (it is in the book) until it makes good contact. An emergency fix might be to take some feeler gauges, put them under the side of the starter mounting base, then tighten the starter back down and kind of tilt the starter gear a bit towards the flex plate teeth and see what happens. Trial and error, until you get some results, if any. Unlikely to be any worse than you have now, unless you shim it way to much. If you find a thickness of shim it seems to like, make something the same thickness out of sheet metal or even plastic.

I remember somebody talking about making an oval of the bottom mounting bolt hole to get the starter gear closer. I might try it in a bind, I have a few extra starters.

I pull $15 dollars starters out of the junk yard, put new brushes in them $20-$30 and keep a couple of spares on the shelf in the garage. It only takes one moderate mud hole to screw up a starter, hard to push start an automatic. I've got 25 year old starters in the garage, they really don't screw up much, mostly the brushes wear our or get gummed up periodically.
 
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yes the bendix did what it was supposed to when tested, i'll run a new solenoid wire this evening for sh!ts and giggles.
heres a pic of my flex-plate
IMG_0552.jpg
[/IMG]
bolts are all tight and no cracks to be seen,
this spot seems to be the worst wear spot on it,
would that cause the teeth of the starter to slip off?
if so,why then when i rotate it manually it still does the same on a spot that looks perfect.
i'll try the coat hanger trick, hope that tells me nothing lol, so do not want to pull that plate

I wouldn't be concerned about those teeth. The ring gear in my wife's 88 is worse than that and it works fine.

Taking the starter apart on these Jeeps is cake. Might see what you find inside.
 
Check the battery voltage while cranking. If it drops below 10 Volts at the battery the ECU will not fire the engine.

Sounds like a bad starter. We are all seeing a high frequency of bad new parts. I don't think any starters for XJs are new, just rebuilt? So even a new Starter is Highly suspect. I have had brand new (fully 100% rebuilt, all new parts, starters fail). And it had your exact problems.
Is the starter always free wheeling now, or just sometimes, does it ever work properly, how frequent is each symptom? How repeatable is the problem?

I would also get a much closer look at the flex plate, but I would try an alternate starter supplier before I did anything new.
 
thx to all for the replies. Eco; half second of crank and then free spin, every time i turn the key and wont stop until i let off, did work proper until the next morning after a "smasher" of a run, unfortunately the only thing ive got done is put the new cps in and shake the hell out of the starter which is tight, (work, kids) tomorrow after work i have to help a friend replace a starter on his van, Thursday ill be able to put your suggestions to use, and ill post up when i loose light. Thx to everyone again
 
so i just tried jumping the solenoid, got he same results, talked to the boys at O'Reilly and they'll swap starters with me so at lunch tomorrow i'll do that and post up
 
when you pull it off, try turning the drive gear both directions by hand-- it should turn fairly easily in one direction and tough the other direction. It can snap out and spin on the bench, but if the over-run clutch has failed, it may not be able to turn the engine without slipping the gear drive.
 
when you pull it off, try turning the drive gear both directions by hand-- it should turn fairly easily in one direction and tough the other direction. It can snap out and spin on the bench, but if the over-run clutch has failed, it may not be able to turn the engine without slipping the gear drive.

Great explanation. That is what was wrong with my all new parts rebuilt starter, that gave me the same problem after about 3-4 good starts. I have seen it described as a bendix or one clutch IIRC, as well.
 
party1:SHE'S ALIVE!!!!!!!!!!!!!!!!!!!!
stupid starter. swapped it out and she fired right up, better now in fact. i'm thinking the new cps has something to do with that. so thank you very much everyone, learned quite a bit for such a stupid problem.:worship:
 
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