OK, I have a 74 Duster with 318, non AC. My negative cable from the battery appears to have a fusible link, split off from the main negative cable to the block, going from the battery terminal to the radiator support, the mounting point is shared with a another ground from what looks like a wire from the headlight wire harness. So, the fusible link broke down and melted. Once this connection was lost I lost all power. We reconnected the wire and found power came back and there are no problems with turning on lights, horn etc. The problem begins once you crank the engine over. Since the coating has melted off the wire you can see it and when you crank the engine it turns orange (hot). Now before you respond and say "you have a short", I get that. Is there a common problem that occurs with these things that could give me a good starting point? I may be able to provide some key information that I may have missed, let me know, thanks.
Fusible link???
- Thread starter Duster_71
- Start date
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That sounds odd to me, although I'm no wiring guru by any stretch. I would suggest checking ALL of the grounds, and make sure they are all good clean connections.
Can you post a pic.
I have a 74 Dart Sport, and I don't believe mine has that link in the ground.
Here is a PIC.
Pawned
N.R.A. Lifetime Member - And damn proud of it
I do not believe that is the fuseible link. That is a wire that is 100 - 125k miles old. Replace the cable
Yeah, that's just a ground wire to the core support. Like I said, make sure ALL of your ground points are clean (such as cleaning to bare metal there), that would be a good place to start.
You may very well have another issue though.
OK, I buy that the wire may be old but what would cause it to melt down like that even though its a ground wire?
67Dart273
Well-Known Member
That is an indicator that quite high current..........higher than normal......has flowed
It might be that the main ground cable to the engine is "not actually ground" anymore, either corroded inside the cable, or whatever that could cause a partial open from the battery NEG to the block
Have you added any high current accessories? Electric fans, or a big stereo?
You must understand, that unless additional jumper straps have been added, there is a VERY poor ground between the engine and body. That is the original purpose of that small ground from the battery to body
Originally, that was to conduct current to "body" grounded stuff such as lights, heater, radio, etc.
Again, something has caused abnormal high current flow.
It might be that the main ground cable to the engine is "not actually ground" anymore, either corroded inside the cable, or whatever that could cause a partial open from the battery NEG to the block
Have you added any high current accessories? Electric fans, or a big stereo?
You must understand, that unless additional jumper straps have been added, there is a VERY poor ground between the engine and body. That is the original purpose of that small ground from the battery to body
Originally, that was to conduct current to "body" grounded stuff such as lights, heater, radio, etc.
Again, something has caused abnormal high current flow.
I think you may be on to something. The problem seems to be most notable when cranking the engine. It would stand to reason that if my battery to block neg connection was poor then more current would flow through that smaller connection while cranking engine. Tomorrow I'm going to double check my battery to block connection again and go from there. I did replace the radio several months ago but did not add any big amps or anything so I wouldn't think it would draw anymore/much more juice.
AJ/FormS
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What Del said.
You may have to cut the clamp off, and strip the insulation off. If you find a greenish-blue powder in there keep stripping. You are looking for shiney copper. Then go check the other end.If the cable gets too short, well,you know...........
You may have to cut the clamp off, and strip the insulation off. If you find a greenish-blue powder in there keep stripping. You are looking for shiney copper. Then go check the other end.If the cable gets too short, well,you know...........
That's what I was gonna say. The larger ground cable is no longer grounded to the block so all current is forced to go through the smaller cable. Probably melted under cranking. I've also seen negative cables that looked okay, but once you cut them apart, they were filled with the green powder that AJ is talking about.
I'd put a new ground cable on it and see if that doesn't fix things.
mderoy340
Well-Known Member
Stick an ohm meter lead on block and neg battery post. If not close to zero remove cable and test the cable. The smaller cable is an overloaded wire not a fusible link.
67Dart273
Well-Known Member
Sorry but disagree. It is simply too darn difficult to test cables this way, as the lower the resistance gets, the more difficult it is to get an accurate reading, especially when FRACTIONS of an ohm are what you are really looking for
Best way to test high current stuff is by voltage drop under load. Clip one meter lead to the block.
Set the meter for low DC volts. Stab the remaining lead into the clamp on the battery, and jumper the starter relay. Read the meter while the engine is cranking. You are hoping for a very very low reading, the lower the better. This might be subjective, but I'd say more than .2V under cranking means you have a problem. More than .3--.4V (3/ 10 of one volt) you DEFINATELY have a problem.
You can ALSO check the drop across the clamp --to -- post connection the same way. Clip one meter lead to the clamp on the neg post. Stab the remaining lead into the top of the post itself, crank the engine. You should have VERY little reading, perhaps barely .1V. Much more, remove, clean, and reclamp the connection.
ALSO don't forget that it's possible this "meltage" the OP detailed COULD have been accidental. "You" (someone) was working on the car, had the ground disconnected from the engine block. You went to bump the engine over or start it and forgot to re-attach or tighten that bolt. It would not crank, then you (someone) "remembered" and hooked it up. The pictured cable has now been smoked
"Long ago and far away" I had had the engine apart in my old 70 (440-6 RR), installing a cam. I had a trunk mount battery, and had forgotten the subframe --to-- engine ground I'd added, which must have been on a timing cover bolt
So I get the new cam all in, and everything is ready, except the forgotten ground. The engine is "sitting" there with very little to ground it. Two tiny straps at the rear to the firewall
I got in, twisted the key, and it all groaned, stuttered the starter relay. I guess I "tried it again" Next thing I know, there was "arc welding" under the dash!!!!
The current, looking for somewhere to ground, had MELTED one of the spring clips off the clutch linkage!!! Under the dash!!! It fell off and down at my feet!!!
Rustedwrench
Well-Known Member
Well, it wasn't a fusible link before but it sure is fused now. Like the others said, the starter current is trying to get back to the battery through that little wire because the starter/engine is not properly grounded. The current has found a path to the body through some other metal which may or may not have suffered damage. It could be anything. Throttle cable, shift linkage, speedo cable, etc.
mderoy340
Well-Known Member
67Dart273
Well-Known Member
This sort of thing also happens in house / building wiring. I once responded to a "no heat" call and the tip-off is the description of the customer
"I think we were hit by lightning. The lights and other things in the house are doing weird things. Some of the lights are bright, and they go brighter or dimmer when you turn things on or off"
Yeah you did, and you have an "ungrounded neutral." What is happening is that "half" the 120V loads are in series with "the other half" on the other side of the neutral center tap
We "did" a building in Rathdrum, an old Safeway they moved out of into a new building. A (I think Garbage) truck snagged the service drop, damaging it, and tore the neutral loose. Somehow, this turned all the metal conduit inside the attic into a gigantic hotplate. It also "cooked" the gas in the natural gas piping.
So the fire boys came, and after that the electricians came, and after that I came over to resurrect the heating / HVAC. I ended up at the "far end" of the nat gas piping, with a propane torch at the end of a flex connector held away, with the torch "pilot light". I had to bleed gas for a LONG time before I got a clean flame.
It destroyed a number of boards in HVAC equipment. This was a 208 or 240V three phase system. This type of damage can hide itself before you get everything checked out. We were back there several times before it was over
"I think we were hit by lightning. The lights and other things in the house are doing weird things. Some of the lights are bright, and they go brighter or dimmer when you turn things on or off"
Yeah you did, and you have an "ungrounded neutral." What is happening is that "half" the 120V loads are in series with "the other half" on the other side of the neutral center tap
We "did" a building in Rathdrum, an old Safeway they moved out of into a new building. A (I think Garbage) truck snagged the service drop, damaging it, and tore the neutral loose. Somehow, this turned all the metal conduit inside the attic into a gigantic hotplate. It also "cooked" the gas in the natural gas piping.
So the fire boys came, and after that the electricians came, and after that I came over to resurrect the heating / HVAC. I ended up at the "far end" of the nat gas piping, with a propane torch at the end of a flex connector held away, with the torch "pilot light". I had to bleed gas for a LONG time before I got a clean flame.
It destroyed a number of boards in HVAC equipment. This was a 208 or 240V three phase system. This type of damage can hide itself before you get everything checked out. We were back there several times before it was over
Thanks Guys!! The ground to the block was not making good contact at the point I had it fastened. I chose a new spot and sanded it and refastened the ground, now everything is fine. I was worried that I had a short somewhere and was going to have all kinds of trouble tracking it down. I learned something and was able to pass this information on to several guys that tried to help me out. Anyway, one bad connection and a piece of $0.50 wire cost me a $75 ride on the roll back, lesson learned!!
Good deal, I would suggest doing the rest if you haven't already.
Pawned
N.R.A. Lifetime Member - And damn proud of it
Just replace the entire ground cable (after reading this I am going to replace mine also).
A fuseible link or any other fuse for that matter will never be placed on the ground. It must be on the power side of the device.
If it was higher voltage and the fuse was on the negative then if you touched a device while touching a fender or some other metal, it would give you something to talk about (shock)
You may feel something at 12 volts by nothing live 116 vdc like I have touched. Feels like someone hits you with a baseball bat on your entire body. Hurts bad
A fuseible link or any other fuse for that matter will never be placed on the ground. It must be on the power side of the device.
If it was higher voltage and the fuse was on the negative then if you touched a device while touching a fender or some other metal, it would give you something to talk about (shock)
You may feel something at 12 volts by nothing live 116 vdc like I have touched. Feels like someone hits you with a baseball bat on your entire body. Hurts bad
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