Ok so I went to bleed my clutch a little after replacing the master and slave a couple weeks ago. After a few minutes off working, this sizzling and popping started. It's loud enough to hear anywhere I'm standing in my small garage, and this has me completely stumped. My thought is spark plugs are firing for god knows what reason? It sounds like bacon getting cooked with a pop every few seconds. The car has been off for about a day now and has never made this noise, so it can't be heat bubbling coolant or anything.
Ok while writing this I disconnected the negative battery cable and the sound stopped which just backs up my spark plug theory even more. It's a 12a with emissions removed and semi new ngk plugs and wires of which I do not know the brand. If anyone has had this problem or has other opinions please let me know. Also when the sound first started the relay box (don't know what it's called) where the plug wires go to was a little toasty. No damage to any wires that I can see. Thanks.

 

You have a short somewhere. A power wire is arcing. Also make sure the ground wire from the battery is good and connected to the starter and the ground at the front driver side strut tower.

For the spark plug to make this type of noise, the ignition would need to be cranking or a short in the ignition. Maybe a bad coil?

 

The dizzy would have to be spinning to cause spark. Did you mess with the big negative that hooks to the engine, the ones going to the starter, or the condenser mounted near the upper inspection plate? It could be a faulty ignition switch sending 12V switched to the starter solenoid. Or maybe a faulty circuit causing the emissions solenoids to pulsate.

 

I'll have a look at the grounds and other wires. I pulled the distributor plugs and it was still making the noise so not spark plugs I guess. Could it be two uncovered wires touching?

 

I was trying to pinpoint the sound and found that it was coming from the rad. I looked under the front and saw the horns so I put the key in the ignition and beeped it once and the noise stopped. I've noticed lately my horn beeps sometimes when I turn the ignition. Not sure why it's happening but at least it's nothing serious

 

It's either the connection to the horns or your FB is possessed.

 

Or the horn button is too tight. Pull the cover off and make sure the plate isn't screwed in too far.

 

The horn isn't on the wheel, it's wired to another button. But it does look like the horn wires go to the same relay where the spark plug wires are connected.

 

A horn button? Sounds like some electrical gremlins.

 

Can you post a picture of this relay?

 

The gray wires are the horn, I'm pretty sure. They run from the horns out front to the inside of the car. And the red are the plug wires.

 

First thing I would do is trace every one of those wires back to know what each is connect to. Then cross reference each one that is hooked to factory wiring. If someone else did the wiring for this, don't trust it until you have validated where everything is going.

You say it doing to the same place as the spark plugs wires? This throws up read flags to me. Can you get a pic of what you are talking about when you say "the horn wires go to the same relay where the spark plug wires are connected"?

 

The pic I posted was of the "relay" I was talking about. I don't know if that's what it's actually called. I havent really had time to scrounge around an inspect those wire thoroughly. This weekend I will though. One thing I do know is that one of the red wires goes to the positive battery cable.

 

What you have in the pic is a pretty standard automotive relay with the plug. The plug is a nice feature. One thing you might try is to unplug it and see if your issue goes away and you can still start the car. You'd still need to fix the horn but at least you can start narrowing it down.

 

Ah ok. I plan on resto-modding the entire car including wiring once I get some more experience. Thanks for the help.

 

Personally, if it were me - that popping noise is the battery arcing 12v and amperage across a short somewhere, and could lead to an engine fire. I'd disconnect the Neg. Battery cable from the battery when you leave it unattended.

Also, it's clearly not ignition system or spark plugs. It's probably not your horns, either. It IS going to be a 12v hot wire somewhere that's rubbing against the metal body somewhere or has burned through to another grounded wire for something else.

When it does this cracking and popping sound, see if you can get it in a dark garage, jack it up and slide under it - you should see some blue sparking from wherever that connection has gone bad. This is something you DEFINITELY need to get fixed (*on your own or pay somebody), because it has the potential to burn your car to the ground or leave you stranded at the very best case. Good luck, and post back.

Sidenote - that relay you posted a picture of is non-standard to these cars, so I'd look at where the wires go and if it's not a necessary feature, then remove everything having to do with that relay. While you're there look for any other wiring not in a plastic loom or wrapped in electrical tape from the 1980's and go from there,

 

Thanks for the information. I haven't heard it at all since I first posted this, but if I do I'll be sure to address it immediately. I'm pretty sure nothing but the suspension bushings is original on this car, which could be a good or bad thing I suppose.

 

Probably an aftermarket radio relay or something to that effect. There is a constant 12v wire in the transmission tunnel harness. A thick black yellow I believe. It is bullet style and the insulator tends to be knocked off from debris so that could be hitting the transmission and shorting.