Question for you master mechanics

RBManufacturing · Jun 9, 2004

Hi Guys, Well I checked the ignition wiring, installed a new magnetic pickup in distributor, and replaced carb AGAIN. I think we are getting closer. I did discover that the coil gets VERY hot after it runs for 5-10 minutes. It does not have a ballast resistor. I will put one on today, even though it does not require one. Also, the ignition module gets pretty warm. Not sure if it is suppose to. But as I said, the coil gets very hot. I don't believe it should. RIGHT??? I checked the altenator to make sure she is not overcharging and causing coil to overheat. Putting out 15 volts. What is the difference in a standard coil, and a heavy duty? I installed a standard. Could it make a difference in coil over heating? I can say one thing about all I have re-placed. When she does run, she runs Great! She will only run about 10 minutes though. Thanks for any help guys. A debt of gratitude, and a FREE tiltmeter to the one that comes up with the solution! This is getting expensive, and very frustrating. Besides all the parts, the wife makes me put a dollar in a CURSE word jar when I say bad words. The jar is overflowing! The neighbors are starting to take their kids inside when they see me raise the hood on the jeep. Thanks, Rick /forums/images/graemlins/confused.gif

gspig · Jun 9, 2004

This could be the same dreaded problem that happens to 8N tractors. The coil will fail when hot. You might try a ballast resistor with a NEW coil. If you are using the coil that you said is getting real hot, the damage is done.

California · Jun 9, 2004

Ok after you've tested and replaced everything else... Here's one of the most unlikely possibilities.

I had a similar experience with a 401 Wagoneer I bought from a 'mechanic' who held a smog cert license. Even he couldn't get it to run right. I think it had the same distributor as your 258-6.

After replacing nearly everything as you have done I discovered the real problem: the wire from the distributor's mag pickup went to a terminal, where there was another permanent wire that would rub against the distributor enclosure - but only when the vacuum or centrifugal advance rotated the plate that the pickup was mounted on. It was hard to identify the problem since the wire looked fine, had plenty of clearance when viewed with the engine off, and seemed to be mounted in its original position.

It had worn through the insulation so every time that wire grounded, the coil would fire an out-of-time spark to whatever cylinder the rotor was pointed toward. This explained why it would sometimes try to run backward when starting. Replacing that wire solved the problem.

Unfortunately that turned out to be #1 of about 50 difficult problems I discovered on that Wagoneer so I traded it to a Jeep/AMC dealer soon after. Then I started getting calls from a local agressive high-profile attorney who bought it at the auto auction and wanted to hold someone accountable for all the problems he discovered! I explained that's why I didn't sell it private party and he should look to the dealer who auctioned it. I think he called me three different times over the course of a year, angrier each time. The Jeep dealer must have hung up on him or something.

bgott · Jun 9, 2004

Coils and modules run hot. Electronics in general run pretty warm. What kind, as in make, of ignition system does your Jeep run? AMC never built their own electrical systems and they used different vendors all the time. It might help if we knew what kind of electronic ignition this thing has in it.

Ozarker · Jun 10, 2004

Are the ignition components not original.....ie......has someone converted it?

When I lived in Germany back in the 70's, a buddy of mine had an AMC with a HEI system........coil in cap. His distributor shot craps and he couldn't get another one in time to ship his car back to the states. So I pulled a conventional distributor and coil out of a junk AMC to get him running so he could ship the car the following month.

Two days later he called and it had quit running on him. The points were fried.

What I discovered, (if all else fails read the manual) was that the ignition wires for the conventional ignition had a resistance wire to the coil reducing the voltage to 9v. Cars designed for the HEI didn't have that resistance wire and V was delivered to the coil.

I replaced the points and installed a ballast resister from a junk Mercedes I had and it worked like a champ.

You may have the same problem if someone has converted your ignition components before you bought it.

RBManufacturing · Jun 10, 2004

Hi Guys,
The jeep is suppose to be original according to the third owner. However I do not believe he knew anything about it. He acted like he was not mechanically inclined at all. Not sure that was the case. When I bought the jeep, it had a replacement coil, electronic ignition module,ignition switch etc. According to the repair manual that came with it, it does not require a ballast resistor. But, the local napa store shows it requires a ballast resistor. I bought one, and a new coil yesterday. If it ever quits raining, I will be installing it. I am beginning to think we have a combination of non-compatable parts. I believe the old girl has been modified more than it should have been. Book shows a pollution pump. (not there).
Also shows a totally different type exhaust manifold, and egr valve set up. What I cannot understand is why she ran great for 2 months before deciding to quit. All parts I originally replaced were exact replacements for the ones removed. There is no makers name on coil, or number. No name on electronic module either. All parts I am replacing are what napa says it calls for. I'll keep you posted on new coil / ballast installation. Thanks, Rick

To20Chris · Jun 10, 2004

Check the vacuum operated emissions system parts. Thermal vacuum switches control much of emissions devices. If it runs until it reaches the switch temp, then it opens up a defective device (say a diaphragm with a big leak), then that could kill it. You’ll want a Jeep vacuum diagram. Look at the EGR, charcoal canister purge valve, spark advance system, air cleaner intake shut off (’76 may be too early for that), etc. Watch the engine temp when it craps out – if it is consistent, then I would strongly suspect the thermally operated vacuum control systems.

kensfarm · Jun 10, 2004

I had a old 76 CJ5.. w/ electronic ignition. I remember my Dad coming out one night telling me I needed to stop working on it because they were trying to sleep. I broke down more then I can remember.. once on the grates on the 14th street bridge coming out of DC in rushhour.. even caught fire one day cruising w/ friends in VA.. the car next to us was nice enough to tell us the jeep was on fire.. we didn't know.. until our buddy in the back seat stands up and screams.. "We're on Fire!!" One winter in college my Jeep top was an old Army poncho.. I had no money so I was sewing together a new top.

There wasn't much I hadn't worked on.. replaced.. or rebuilt on that jeep.. but I tell you.. those were some of the best times in my life.. man.. the memories.. wish I had it today to run around the farm in.

The electronic pickup sensor in the distributor is bad.. works until it gets warm.. then engine will shut down. I would replace that first.. then look at replacing the electronic module. This was the problem I had after installing a brand new distributor.