Started the 72 Cutlass for the first time this year. The hood was open and my friend observed a spark on the bolt of the Horn Relay - Junction Block (see green circle on attached image) I also saw the flash from the driver's seat.

Clearly I should clean it up, but any thoughts on other stuff to consider before I try to start it up again?

 

It's probably loose and corroded. I'd take it apart, check all the terminals and clean it up.

 

+1. Tighten it.

- Eric

 

The same thing happened to me a few years and then the fusible link went

 

Clean and tight applies to all the connections you can get your hands on, on a 45 year old car. Grounds are your friend The main and secondary grounds are all important. Make sure the factory ground straps are present and accounted for. Same goes for that weird shaped bracket heavy duty (ground strap) attached to the starter to the block that everyone tosses out first starter change...

 

Those terminals look quite bad. Disconnect battery, take each off and wirewheel them with a dremel. Gently tug on each. If any come apart, they were bad and need rework anyway.

 

Great advice (as usual).

It took a bit of Kroil & PB Blaster to get the bolt off, but after I cleaned everything up and got it nice and tightly put back together it works like a charm.

Thanks.

 

Now that its clean and tight. Hit it with brake cleaner to remove Kroil & PB then hit it with clear ignition sealer. Mask off the area to do both if thats a concern. That will seal the connection and keep it nice for years to come.

 

Have never used that.

What is the advantage of clear ignition sealer over some dielectric grease?

 

Looks prettier and doesn't attract dirt. Basically clear paint.