fuse keeps catching fire.

[Dirtyowlnumber4]

There is a 20 amp fuse in my fusebox for all the parking and running lights and the dash lights. When I pop the switch nothing happens until i fiddle around with the fuse for a second. Then the fuse starts popping and sparking and heats up to an incredible temperature until it starts melting the fusebox. The lights all function perfectly as well, I drove it for half an hour last night not realizing that the fuse was red hot. The glass on it turned black, but it was still conducting electricity.

 

Checked all wires for the running lights, didn't see any short must be one somewhere I was just wondering why the fuse might be heating up so much and not blowing.

[datzenmike]

The clips that grip the fuse are probably corroded. This adds resistance and resistance causes heat, just like your toaster. The problem is the heat will also soften the clips and remove their ability to tightly grip the fuse which just makes things worse. Your only cure may be to replace the fuse box.

[Dirtyowlnumber4]

okey doke couldn't hurt thanks 

[Crashtd420]

okey doke couldn't hurt thanks

The only other thing it could be is if you have you added any other components to the circuit, or upgraded any of the lights and now your drawing more current through that circuit...

[banzai510(hainz)]

I have alot of issues with the fuse box area myself. key is clean and reseat them.

Alwasy ck them first if lights ,ignition alternator issues.

 

 

Yesterday My 8 month old(10K miles ) Alternator from O Rileys took a shit. . First I reseated the fuses. to make sure the 12volt go to the Alt to exict the coil in Alt. Well seemed ok and changed out the Alt only till the nex day My lights didnt work. I thought it was my H4 harness was the proplem as when I take alternaots out I always hit the harness. Find out the Fuse connection was just bad from the lights as when I moved it is made it worse.

Everything works now. I am trying a WAI alternator from PartsGeek. Brand New Made in China Alternator . Rock auto sell these also so we will see.

All the AutoZone and O rileys are rebult in China now.  Just sucks. I like running the smaller 35ampers but th rebuilds just suck.

[vicdat]

I agree that early Datsun fuse boxes mounted under the hood are a really weak link so check that component first.

I also have been using lifetime warranty O' Reilly's (formerly Kragen; formerly Trak Auto) alternators on my old Japanese cars...at best I get about a year out of each one before it blows a diode or takes a wicked dump. Fortunately its about a 30 min job on a Datsun (a good hour on my 87 Celica GTS).

 

Vicdat

[datzenmike]

 Lets see, pay $40 for free lifetime replacement alternator. Replace it 3 times which involved getting someone to drive me in and order 'new ones' then go back and pick it up later. Once I had to wait till Monday when they were open and walked to work. One and a half hours wasted changing them. Slept in the car one night because stranded in the dark. Another time had to be towed back home. One seized and burned the fan belt off and over heated the engine. The last one over charged the battery and it boiled over and the headlight don't work now. Pick one.

 

A $25 used stock alternator in a wrecking yard is ten times more reliable and why they were $350 to replace back in the day. My 620's was over 30 years old when I up graded to 90 amp. Probably still out in the shed and ready to go.

 

You pay so that you don't have to.

[datsunaholic]

Problem is, most Datsuns in wrecking yards (when you can find one) already have the alternator missing, or it's an Oreillys rebuild.  Sometimes that being the reason it's in the wrecking yard in the first place...

 

I do agree that if you can find an original unmolested alternator then go for it, but finding them isn't easy anymore.  It sucks having to run crap parts when nothing else exists.

[datzenmike]

If you have an original maybe have it rebuilt..... and I mean at a reputable place and get the original back. 

[KoHeartsGPA]

I just replaced the alternator on my 620 that I had replaced last week, reman is garbage, find an original and have it rebuilt like the guys above me suggested, as soon as I get a chance I'll be hitting the JY for KA alternators and have them tested, if bad I'll get them rebuilt by one of our reputable local shops.

[datzenmike]

Get the truck KA, they have the V belt pulley, although the 620 pulley will fit the car alternator it needs a spacer or it rubs the case, then the nut barely has enough threads. I got the car one for free and just hit it with my MIG welder so it can't come loose.

 

I believe the car alternators are 80 or 90 amp. Early trucks I think 60, later KA24DE may be higher.

 

I have a 2002 Altima 100 amp. The output cable from the alternator was thicker than the stock 710 positive battery cable!!! The Altima had a V6 also but too hard to get at for the same alternator.

[banzai510(hainz)]

I dont go to the Junkyards anymore. and as Datsunaholic said those Jap alternators are long gone.

Even the Hitachi cases are getting harder to find. All the Autozone and O Rileys seem to be Chinese Cased units now anyways.

 

Im lucky as I alwasy have a Cig lighter Volt meter and I catch the unit falure ASAP. So Im not driving around then get a dead battery. I was alwasy close to home.

Im going to Try this NEW CHinese version and hopefully I wont wtite about bad alternators for 10years.

 

 

I get the stock size as I dont like screwing around with a big alt in a 521

 

 

I have had rebult Alt and starters done a guy and they dont seem to lat to much longer either.By then the bearing and case is comming apart

[KoHeartsGPA]

Fortunately for me it's D21 galore in the JY in my area :)

[don51o]

used to work restoring  roadsters, I did the electrics. clean ALL contacts in the circuit: bulb sockets, harness interconnects, etc. Once soldered an inline fuse holder to the fuse "tabs" in the fuse box to save the owner the cost of a fuse box. Clean connections will lower resistance and reduce current draw.

[datzenmike]

Actually, lower resistance increases current flow. Resistance from corrosion or poor contact decreases current flow causing heat.