Fusible link replacement 92 Loyale

[Frank B]

I burned up a fusible link today, and since my fiancee was heading into town, I asked her to swing by Autozone and pick one up, since that was the only place open and I need my car tomorrow. So I right down what I need, red fusible link .085 for an import. Told her what it looked like too. So she calls me a few minutes later to say that they had no idea what she was talking about. No idea what a fusible link was!!! So I told her to look by the fuses and read the packages lookinf for a red fusible link. She said she found it, comes home later with this;

 

It's a fusible link allright, but for the newer cars. It fits right into the slot like it was made for it, my headlights now work, but will it do it's job and burn up the same as the red wire one? It says 50A on it, but I didn't think that fusible links were "measured" in amps like a fuse.

What do you think?

If this is fine I'll replace the others the same way.

[idosubaru]

woah frank! nice hit, never heard/seen that one before!?

 

it's probably fine, but personally i'd prefer the existing system - it protected it this time right? it worked and did it's job i'd rather not mess with that. but it's your car and i'm an electrical goober which will heighten my sense of what to do or not do!

 

i (and others) have tons of old ones, i can probably send you one if you tell me the color? i keep them all from old parts cars just in case since Subaru wants like $10 a piece for them and often doesn't have them in stock.

[somick]

woah frank! nice hit, never heard/seen that one before!?

 

it's probably fine, but personally i'd prefer the existing system - it protected it this time right? it worked and did it's job i'd rather not mess with that. but it's your car and i'm an electrical goober which will heighten my sense of what to do or not do!

 

i (and others) have tons of old ones, i can probably send you one if you tell me the color? i keep them all from old parts cars just in case since Subaru wants like $10 a piece for them and often doesn't have them in stock.

I think he asked for red...

[GeneralDisorder]

It says 50A on it, but I didn't think that fusible links were "measured" in amps like a fuse. What do you think? If this is fine I'll replace the others the same way.

 

How else would you rate it? It's a device desiged to burn up when "too much" current passes through it. Current is rated in Amperes.... ergo how else would you put a number to "too much".

 

I would have to look in the FSM for the specifications on the red link's to tell you for sure if they are 50. Probably. Sounds about right.

 

The concerning part is that you blew one in the first place. And don't go willy-nilly replacing the original's with "new" ones. There's no benefit to that and messing with something that works isn't smart.

 

Find out why you blew the first one. That should NEVER happen.

 

GD

[idosubaru]

How else would you rate it? It's a device desiged to burn up when "too much" current passes through it. Current is rated in Amperes.... ergo how else would you put a number to "too much".

i was under the impression that there were some fuses that instantly broke. and then there were other types that were designed to fail with a load over a period of time, but not instant. i thought the fusible links were of the latter variety and the inside fuses were of the first.

[Frank B]

I should have mentioned this, but I was the cause of the fusible link burning up. So I know what the problem was, me tapping into the wrong circuit. Anyway, the fusible like is a slow burning fuse, it acts differently than a little bus fuse. I just don't rememebr ever seeing a amperage rating on them, it's usually just a size like 12 or 14 guage, or .85 or .5. It's a smaller diameter conductor that will burn up before the circuit wiring does to protect the circuit, like an intentional weak link, or sacrificial link.

 

I just wonder if the color coding is the same? The older wire type red vs this plastic box red one , green wire vs green box , etc.

I

[Cougar]

You are correct about the melting characteristics Frank. They are more like a delay or slow blow fuse. Here is what my FSM manual states about the red colored link.

 

The gauge size is 0.85mm2 and should have less than a 60mV voltage drop across it when a 10 amp current flows through it at room temperature. The fusible link should melt within 15 seconds at a current flow of 130 amps.

 

I would leave the other original links in there though you could purchase some newer style ones for backup. The green is 80 amps and the black is 190 amps. Like GD said, these links should never have to be replaced if things work like they should.

[Frank B]

these links should never have to be replaced if things work like they should.

 

If the mechanic worked like he should have, it never would have burned up .

 

I have seen these all corroded, so I'm sure there's a service limit to them. But anyway, I probably will leave them alone now. I'm getting better at not fixing what isn't broken.

[GeneralDisorder]

i was under the impression that there were some fuses that instantly broke.

There is your mis-understanding. All fuses have some sort of time-delay. Although the common automotive fuses aren't usually marked with this sort of rating as they do blow "almost" instantly - for most purposes.

 

Fuses that most people come in contact with are designed that way. But most of your three-phase industrial fuses are time-delay. This is because across-the-line starters and such draw down HUGE amperage when starting three phase motors. 7 to 10 times the rated full load amps (FLA) of the motor. Time delay fuses or breakers are employed that allow for that.

 

The 12v DC variety of fuseing though is not done this way. The links are there primarily to prevent fires from direct shorting or bypassing the fuses, etc. They are designed to melt rapidly when you exceed their rating - IE: before the wireing melts and catches fire. 130 amps through a 10 or 12 AWG wire is a LOT. I hope 15 seconds is wrong as that would likely leave the car pretty crispy. If you actually melted one, I wouldn't be surprised at all if you melted wireing insulation elsewhere in the harness if that 15 second rule is accurate.

 

GD

[Cougar]

I agree GD, 15 seconds is a long time but it does say that in the manual.

[Frank B]

It didn't take 15 seconds for this one to burn up, it was more like 1.

[GeneralDisorder]

It didn't take 15 seconds for this one to burn up, it was more like 1.

 

That's what you would expect, but without knowing how many amps you were pushing though it... could have been several hundred if it was a dead short. The spec is at 130 amps - which is a LOT. For conduit runs that will see 130 amps (that's about a 125 HP three-phase motor) the specification is for 250 Amp time-delay motor rated fuses and 3/0 (000) wire. Stranded copper as big around as your thumb (and I've seen those get hot). Thus my concern at this 15 second number....

 

GD

[Frank B]

If the stock wire one is supposed to handle 130 amps, then this newer design plastic box 50 amp one should be just fine. My lights worked on my way home from work last night just fine. It turned on everything I could find with the highbeams on, and while playing with the window switches, and all was well.