Timmmmmy Posted October 9, 2013 Share Posted October 9, 2013 Hey guys, for the last year my truck 4.L Renix 89 has randomly not started. At first it happend every few months, then in the last month it has happend about 5 times. Over the last year I have tried to figure this out. It has a new Optima Yellow top, distributer. I have had the aternator, fuel pump starter, and charging system checked numorous times buy a legit mechanic. All check out fine. Up until last month the truck wouldn't turn over at first. I would turn it over 2 or 3 times and then it would fire up. Then last week it wouldn't start at all. I had someone jump me and I got it to run. It ran fine for a week and then today after work it died completly. I had a co-worker jump it and had cables on it for ten minutes. No luck. My truck now sits on the street and I'm on the bus. I started watching the batery gauge in my cluster last week. Often at night when I'm driving I will turn the lights on and the gauge will drop almost into the red. I turn the lights off and the needle goes back up a fair bit. My mechanic checked this out and said he noticed it but that the gauge appears to be not that accurate. Has anyone come accross this before? Sounds like the alternator but my mechanic is telling me that it is working. Any input would be very appreciated. Thanks Link to comment Share on other sites More sharing options...
Eagle Posted October 9, 2013 Share Posted October 9, 2013 It almost certainly is the alternator. I went through this with my '88 Cherokee and again with my '88 Comanche. Remove the alternator and take it to Autozone or Advance Auto to have it bench tested. Link to comment Share on other sites More sharing options...
yxmj Posted October 9, 2013 Share Posted October 9, 2013 If you have access to a volt meter a quick test is: Start the truck.....turn on the park lights......measure the voltage across your battery terminals.....it should be between 12.7 to 14.8 volts any lower or higher and it is the alternator If that is the case i would look into just replacing the brushes first.......I just did a couple and it only cost $8 per and my time (about 1hr) :thumbsup: Link to comment Share on other sites More sharing options...
Comanchemodder Posted October 9, 2013 Share Posted October 9, 2013 A little clarification on using the voltmeter: 1) If the alternator is not working, the voltmeter will read12.5-13 volts (battery voltage) with the engine running or turned off (no major change). 2) If the alternator is working, with the engine running, you will expect to see 14+volts on the battery. Link to comment Share on other sites More sharing options...
yxmj Posted October 9, 2013 Share Posted October 9, 2013 A little clarification on using the voltmeter: 1) If the alternator is not working, the voltmeter will read12.5-13 volts (battery voltage) with the engine running or turned off (no major change). 2) If the alternator is working, with the engine running, you will expect to see 14+volts on the battery. Yes :thumbsup: Sorry I was Vague Another fast test is start the truck and pull the positive battery cable off.....if it keeps running ALT is good.....if it dies........Break out you $8 for brushes Link to comment Share on other sites More sharing options...
gogmorgo Posted October 9, 2013 Share Posted October 9, 2013 Another fast test is start the truck and pull the positive battery cable off.....if it keeps running ALT is good.....if it dies........Break out you $8 for brushes :doh: Yeah, don't do this... You might get away with it a few times, but the load dump will fry things. If the truck dies, it could be because you just hit the ECU with 100 plus volts. Much safer to have the alt bench tested. You'll need to pull it anyway to swap out the brushes... Link to comment Share on other sites More sharing options...
mvusse Posted October 10, 2013 Share Posted October 10, 2013 Every alternator I have had on my 4.0, the brushes are not meant to be replaced. To get to them means to dismantle the alternator about 90%. If the alternator is bad, buy a reman lifetime warranty 100 amp alternator for $65. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 10, 2013 Share Posted October 10, 2013 And when you get done with the alternator issue, do this: Renix Ground Refreshing The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily. The components grounding at the dipstick tube stud are: Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff. The factory was aware of the issues with this ground point and addressed it by suggesting the following: Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint. Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely. While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely. Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end. First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.Remove the other end of the cable from the rear of the head using a 3’4” socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely. A suggestion regarding the braided cable:I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18” long with a 3/8” lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116. A further improvement to the grounding system can be made using a #4 cable, about 10” long with 3/8” terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115. For those of us with Comanches, it’s very important to remove the driver’s side taillamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal. Reattach securely. If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price. Revised 03-04-2013 And this: I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals making sure they haven’t retracted into the plastic holder, and then plugging it back together. There’s a critical 10-pin connector for the front lighting system located in front of the air cleaner and behind the left headlight assembly. Don’t miss that one . Also be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight. ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then plug them back in. I do this on every Renix Jeep I purchase or work on for someone else. Revised 07/23/2012 Link to comment Share on other sites More sharing options...
Timmmmmy Posted October 23, 2013 Author Share Posted October 23, 2013 Hey guys, sorry I didn't you an update earlier. I went to work the next morning, truck fired right up, no hesitation. I then drove it back to my mechanic. They kept it for a week. Several times a day they fired it up, turned everything on, let it idle. They could not get it to not run. They did every test they could on it and no luck. So I took it home and it has been fine since, till tonight after work, rode the bus again. lucky the mechanic is a friend and i wasn't charged anything. He had a jeep with similar problems and it turned out to be a Crank shaft positioning sensor, not sure it that makes sense. I will get the truck back to him and tell him to check all of cruisers tips. I am tempted to do the alternator regardless. Again driving if I turn the lights on, the dash voltimeter lowers a few centimeters, if I turn on the heat it drops further, almost to red line. Ill update when I can. Link to comment Share on other sites More sharing options...
mvusse Posted October 23, 2013 Share Posted October 23, 2013 Sounds like your alternator is mostly fried. Link to comment Share on other sites More sharing options...
yxmj Posted October 23, 2013 Share Posted October 23, 2013 Another fast test is start the truck and pull the positive battery cable off.....if it keeps running ALT is good.....if it dies........Break out you $8 for brushes :doh: Yeah, don't do this... You might get away with it a few times, but the load dump will fry things. If the truck dies, it could be because you just hit the ECU with 100 plus volts. Much safer to have the alt bench tested. You'll need to pull it anyway to swap out the brushes... Just to be clear I did not tell him to do it multiple times.....once would give you the answer. :thumbsup: Link to comment Share on other sites More sharing options...
yxmj Posted October 23, 2013 Share Posted October 23, 2013 Every alternator I have had on my 4.0, the brushes are not meant to be replaced. To get to them means to dismantle the alternator about 90%. If the alternator is bad, buy a reman lifetime warranty 100 amp alternator for $65. Sorry you had a bad experience…..almost all alternators on all vehicles have replaceable brushes. Most jeeps are around the $8- $12 range http://www.autopartsnetwork.com/jeep-comanche-rx-103-alternator-brush-set/bvbF_WdgtFqlUp Here is a general guideline (this is a newer Cherokee but the basic steps are the same) This covers a complete rebuild but if you do not have bearing issues then just look at the parts related to brush removal and replacement. Once the alternator is out it is just 4 bolts to remove the back cover and 3 screw to remove the brush holder (YOU DO NOT HAVE TO DO ANY MORE BEYOND THAT IF YOU ARE JUST REPLACING THE BRUSHES) http://www.jeepforum.com/forum/f11/rebuilding-nippon-denso-alternator-00-01-56041822aa-835511/ . :MJ 1: . Link to comment Share on other sites More sharing options...
gogmorgo Posted October 23, 2013 Share Posted October 23, 2013 Just to be clear I did not tell him to do it multiple times.....once would give you the answer. :thumbsup: :no: It's still poking the sleeping bear. You might not always wake him up on the first try, but that doesn't mean it's not possible. Link to comment Share on other sites More sharing options...
mvusse Posted October 24, 2013 Share Posted October 24, 2013 Every alternator I have had on my 4.0, the brushes are not meant to be replaced. To get to them means to dismantle the alternator about 90%. If the alternator is bad, buy a reman lifetime warranty 100 amp alternator for $65. Sorry you had a bad experience…..almost all alternators on all vehicles have replaceable brushes. Most jeeps are around the $8- $12 range http://www.autopartsnetwork.com/jeep-comanche-rx-103-alternator-brush-set/bvbF_WdgtFqlUp Here is a general guideline (this is a newer Cherokee but the basic steps are the same) This covers a complete rebuild but if you do not have bearing issues then just look at the parts related to brush removal and replacement. Once the alternator is out it is just 4 bolts to remove the back cover and 3 screw to remove the brush holder (YOU DO NOT HAVE TO DO ANY MORE BEYOND THAT IF YOU ARE JUST REPLACING THE BRUSHES) http://www.jeepforum.com/forum/f11/rebuilding-nippon-denso-alternator-00-01-56041822aa-835511/ . :MJ 1: . Maybe on Nippo Denso alternators used on HO engines. My Renix uses an AC Delco unit, and it is not a simple "remove three screws and the back cover comes off". The brushes are still in the back, but the only way to get to them is from the front by distmantling the entire unit. Link to comment Share on other sites More sharing options...
yxmj Posted October 24, 2013 Share Posted October 24, 2013 Every alternator I have had on my 4.0, the brushes are not meant to be replaced. To get to them means to dismantle the alternator about 90%. If the alternator is bad, buy a reman lifetime warranty 100 amp alternator for $65. Sorry you had a bad experience…..almost all alternators on all vehicles have replaceable brushes. Most jeeps are around the $8- $12 range http://www.autopartsnetwork.com/jeep-comanche-rx-103-alternator-brush-set/bvbF_WdgtFqlUp Here is a general guideline (this is a newer Cherokee but the basic steps are the same) This covers a complete rebuild but if you do not have bearing issues then just look at the parts related to brush removal and replacement. Once the alternator is out it is just 4 bolts to remove the back cover and 3 screw to remove the brush holder (YOU DO NOT HAVE TO DO ANY MORE BEYOND THAT IF YOU ARE JUST REPLACING THE BRUSHES) http://www.jeepforum.com/forum/f11/rebuilding-nippon-denso-alternator-00-01-56041822aa-835511/ . :MJ 1: . Maybe on Nippo Denso alternators used on HO engines. My Renix uses an AC Delco unit, and it is not a simple "remove three screws and the back cover comes off". The brushes are still in the back, but the only way to get to them is from the front by distmantling the entire unit. Well I am sorry your alternator has been such a bad experience for you. But for all those who don't have the extra cash to pay a mechanic .....or who like me just like to roll up their sleeves and get the satisfaction of manning up and fixing something themselves..... here is a good write up on how to rebuild the Delco model.....once out of the truck....$15-$25 and about 30 mins work http://tc.wagoneer.org/2012/08/delco-alternator-rebuild-guide.html http://www.ebay.ca/itm/10SI-12SI-Delco-Alternator-Rebuild-kit-12-Volt-Chevy-brushes-bearings-regulator-/190618856210?pt=Motors_Car_Truck_Parts_Accessories&hash=item2c61c4eb12&vxp=mtr&_uhb=1 :thumbsup: . :MJ 1: . :thumbsup: Link to comment Share on other sites More sharing options...
carnuck Posted October 27, 2013 Share Posted October 27, 2013 Do the ground refresh and voltage test before doing anything ra$h. On the Delco style alt, the plug in wears through the wire after awhile and stops charging. Link to comment Share on other sites More sharing options...
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