Fusible link problem

[cudaken]

 My Fusible link is cooked on my 68 Road Runner. It is the style that is in the engine wiring harness and goes to the starter relay. Wiring harness is a 20 year old Year One harness.

I believe I know how to install one. But here is the real question. I need to track down what caused it cook in the first places. I would like to use a inline fuse holder till I find the real problem.

What amp fuse would I use and should it be a quick blow or slow blow fuses?

Thanks for the coming answers and ideas.

Wiring is my Weak Link.  

Cuda Ken
 

[Dmichels]

60 amp
Unless it is a show car leave it in I will be doing this to mine shortly. Solder your conections and use shrink tubing. Do not use crimp conectors, they suck.
Dave

[Pete in NH]

Hi Ken,

I really have enjoyed pollowing your tale of bringing your car back to life and congratulations on the start up video, it was great to see.

On the fusible link, it should be a blue colored one, which is 16 gauge. It is supposed to melt at about 60 amps or so. You can replace it with a more modern Maxi-fuse, which is a big slow blow type automotive blade type fuse. A 50 or 60 amp one would be fine. The nice thing about maxi-fuses are you can get then anywhere even bigger hardware stores. So if you mount it in a splash proof holder you can easily change should you need to. But, yes, you do need to track down why the fusible link blew. They a last resort safety device to keep the wire harness from burning. Since your car sat for along time anything is possible including some squirrels  chewing in the wiring. I'd be happy to help you track through the circuits if you need some help.

[Canadian1968]

I would start by looking at alternator. Make sure it's not over charging? Then have a look at your ammeter in the dash. Check the connections on back of the gauge they may show signs of burning as well!

[Charger RT]

what amp alternator is on the car?
Tim

[cudaken]

 
60 Amp Fuse? Would Auto Stupid carry something like that? And here I was thinking 10 amps slow blow!  

Pete, thank you for the kind offer! Boy I am going to need some help! Far as furry things liven in the Road Runner, I have seen no signs of that so far. But man the Ants where pissed when Allen and I started working on her! They really hated Allen, he was the first in the trunk!  

OK Pete, you have been following my post. (By The Way Thank You) When I Cooked the link was the night I hooked up a battery charger to dead and 15 year old battery. With in a few seconds I saw smoke off the link. Now I was pretty Cam 2 upped   and there is a small chances that I had the clamps backwards.  

My first thought was the push button hidden under the carpet starter button. When I pulled it, it was very rusty and would not move freely. It is the type of button you push on, but have to push again to turn off. My daughter a few decades ago at Monster Mopar Weekend  hit the button my accident and the Runner started cranking and cranking. Luckily a guy pull a battery cable for her, I was racing the 70 Cuda.

When Allen and I first tried to fire her up, we found the ballast was cooked.

Ken

[MaximRecoil]

60 amp
Unless it is a show car leave it in I will be doing this to mine shortly. Solder your conections and use shrink tubing. Do not use crimp conectors, they suck.
Dave

Every single electrical wire connector installed in the car at the factory was crimped, not soldered. After 44 years, none of the original crimps in the wiring harness in my car have failed. Crimping is ideal for a car environment, because a proper crimp is air-tight (thus the wire strands that are clamped within the crimp will never oxidize), and a crimped wire remains flexible at the points just before and after the crimp. Solder is not particularly flexible, so over a long period of time being subject to vibration and/or large temperature fluctuations, they may crack.

So if you have quality crimp connectors and a proper crimping tool designed for them, crimping is the best thing for a car environment. Soldering is the next best thing. It is a higher resistance connection than you get from copper terminals properly crimped to copper wire (though that difference is practically insignificant unless you have a long run of soldered connections), it is fairly durable (though not as durable as a proper crimp), and like a proper crimp, it won't oxidize within the connection.

"Twist and tape" is the worst thing by far.

[K9COP]

Here we go again. 

[MaximRecoil]

[post deleted]

[K9COP]

Easy Tiger.! I think your reply says more about you than me. Did I dispute your post? Did I say your information was incorrect? Did I contest you? Did I suggest you were steering anyone in the wrong or less-than-ideal direction? Did my post even reference yours?

Calm down pumpkin. 1st amendment and all that. 

CS

[MaximRecoil]

My mistake. I thought you were replying to me.

[Pete in NH]

Ken,

You should be able to find 50 or 60 amp Maxi-fuses at any reasonable auto parts place. My local NAPA has a whole display shelf of them and holders for them.

Replacing the fusible link on your car is a bit of a pain. The one end is simple as it's a 1/4" ring terminal connected to the battery stud on the starter relay. The other end is crimped into one of the bulkhead connector pins, that's the end that is a pain to deal with. One good option is to wire in the Maxi-fuse holder using a 1/4" ring terminal on the starter relay side and then connecting the other side with a new #8 gauge  red wire through a grommet lined hole through the firewall directly to the side of the ammeter with a red wire on it. You would disconnect the present red wire on the ammeter and replace it with your new one. This would be one half of the upgrade Chrysler did at the factory when installing 60 amp alternators. The other half would be running a new #8 gauge black wire from the black wire terminal of the ammeter out through the new firewall hole to the output stud of the alternator. You would disconnect the existing black wire at the alternator output stud, follow it back to the bulkhead connector pin and cut the wire off at the pin. All this is known as the "fleet bypass wiring" and was a factory modification. It completely eliminated the troubles caused by high currents through the bulkhead connector in the battery charge circuit.

The wiring path you want to carefully inspect goes from the battery terminal stud on the starter relay, though the fusible link,through  the bulkhead connector to the red wire side of the ammeter. Through the dash board ammeter to a black wire that feeds the fuse block for all the car's electrical items to another blackwire that runs back through the bulkhead connector to the alternator output stud. I'd start by looking for any cut insulation on that wiring. Do you have a  test meter you can measure ohms or continuity with?

[cudaken]

 Pete, why 60 amp's? My car only has a 40 amp alternator? Now if that is what I have to have, I will get one.

My plans for now is to remove the link, and wire though the the hole that will be left in the hardness and use a spade.I know getting the old one out will be a bitch! I don't fit under dashes to well now! 

Any thoughts to why the ballast cooked? Key was not on when I hooked up the battery charger.

Ken

[K9COP]

Ken, hope this helps. I got my 60A fusible links here:

http://www.summitracing.com/parts/pco-0969pt

I'm putting them in my car during the rewire.

CS

[Pete in NH]

Ken,

I used 60 amps because that is about the maximum the old blue wire fusible link would handle. With the stock 40-45 amp alternator, a 50 amp Maxi-fuse would be fine as well.

On the ballast resistor, what type ignition system are you running, points, Chrysler electronic or something else?

[John_Kunkel]

You can replace it with a more modern Maxi-fuse, which is a big slow blow type automotive blade type fuse. A 50 or 60 amp one would be fine. The nice thing about maxi-fuses are you can get then anywhere even bigger hardware stores.

The fusible link is quite possibly the dumbest thing they ever put in a car. The fuse is a good idea but a breaker would be better IMHO, easier and cheaper to reset a breaker than to replace fuses when troubleshooting a short; you can get one for under $20.

http://www.aircraftspruce.com/catalog/elpages/6070amp.php

[cudaken]

Thanks John and CS for the links. I did find them locally at Advances.

Pete, I run a old Accel Dual Point and had a MSD Coil. We replaced the coil with a factory one I had when we first found we had no spark.

Now the next part of the puzzle. When Allen and I hot wired Miss Lumpy (Nick Name for the Road Runner) Bryan suggested we go through the ballast. (being a Mopar Guy I had a extra one) Me mounted it to the fire wall and hooked the harness leads up Single wire one plastic cover was melted to the prong and hooked the hot wire to the double wire side, nothing. Then we tried the single wire side and cooked the new ballast as well.  Key was not in the car when this happened.

Just some information for you to think about and think to your self "what kind of dumb asses would do that"! 

By the way the alternator and head and tail lights still work if that helps any.

Right now my main goal is to be able to move the car. I don't want to hurt the points or coil by running her. ( 1 set points are now $40.00 and I need 2 of them)  When I run the Hot Wire to the ballast It will not be hooked to the harness this time do I run the wire off the battery to the 2 wire side, or the 1 wire side?

Cuda Ken, bewildered again! 

[Pete in NH]

Ken,

Okay, old points style system. Wow!, $40 for a set of points these days, I would seriously consider converting over to electronic ignition at somepoint when things get fixed up. The way your system presently works is the one wire side of the ballast resistor goes to the ignition run side of the ignition key switch.When the car is in normal run mode the ballast resistor is in the circuit betwen the battery and the plus side of the coil. The two wire side of the ballast resistor is the side that connects to the plus side of the ignition coil. When you are cranking the engine, the ballast resistor is bypassed out of the circuit by the ignition key switch. This way the coil gets full battery voltage when the engine is cranking and the battery voltage is lower with the load of the starter on it.  I suspect there is some thing messed up in the wiring on the start side of the ignition switch wiring and you may be trying to power up the starter solenoid through the ballast resistor.

For the time being until you can track down what is happening I would disconnect the two wire side from the ballast resistorand also disconnect the wire from the positive side of the coil. I would then run a new piece of wire from the positive side of the coil to what was the two wire side of the ballast resistor. That should allow you to run the engine without cooking the resistor until you can check out the wiring.

John, well the one thing you can say for the fusible link wire was that it was cheap and we all know how Detroit loves cheap! I think they eventually realized it wasn't the greatest idea and in the 80's went over to maxi type fuses. A circuit breaker is a good idea but they would never spend the money.

[cudaken]

For the time being until you can track down what is happening I would disconnect the two wire side from the ballast resistorand also disconnect the wire from the positive side of the coil. I would then run a new piece of wire from the positive side of the coil to what was the two wire side of the ballast resistor. That should allow you to run the engine without cooking the resistor until you can check out the wiring.

 

So Pete, + side of coil to the post that would had the 2 wire plug on the ballast. So run the wire from the + side of the battery to the single wire side of the ballast?

Ken

[cudaken]

 Shopping did not go the way I hoped today!

I saw some 50 AMP glass fuses on line, but when I went to the store, they where twice as wide of a normal glass fuse. They all so did not have and holders for the thicker fuses. Best I could come up with was 35 AMP Fuse.

I have a 2 fold question.

1 I am using a remote starter to turn the engine over.
http://s83.photobucket.com/user/cudaken/media/Charger%20Site/8-29-13_zps877791a2.jpg.html]

I am guessing that the highest AMP load happens when the engine is cracking?  By using the remote starter, could the 35 AMP fuses live, well for a while?  

2 Advances had Fuse-able Link wire. But it did not say at what Amps it would melt at? All the package listed was the gauge of the wire. So what gauge do I need?

Thanks for the coming help!

Ken

[Pete in NH]

Ken,

You've got it- wire the + side of the coil to where the two wire connection was on the ballast and the other side of the ballast to the + side of the battery. As I said , this is only a temporary hook up until you can get the rest of the electrical system sorted out. It doesn't bypass the ballast resistor as the original circuit did but should be okay in the warmer weather.

On the fusible link- You want the blue #16 gauge wire. They don't give you the melting current because its hard to really know at what point it really will melt. There are some things like the length of the link wire that come into play. My guesstimate is A 16 gauge will melt somewhere around 50 to 60 amps. The fusible link was a rather crude device that was eventually replaced with real fuses. The Maxi-Fuse is a blade type mounting  and holders are readily available. The circuit with the fusible link is the battery/ alternator charge circuit and the maximum current would be either the alternator rating or amount of current being drawn by the cars electrical accessories which ever is the highest. If you have a 40 to 50 amp stock alternator you would want a fuse that could carry that current without blowing.