Gunk in relay connection

[Dan SS2471]

What causes this kind of buildup in a relay harness? It's like tobacco / syrup. This is the fan high relay on the driver's fender. I replaced the high and low relays last year and recently couldn't get the high to work without mashing the connection together REALLY hard. I finally picked up some CNC contact cleaner and sprayed the harness and relay itself and the connection is good now and works just softly connecting the relay to harness. Pic shows what I'm talking about. Looks like a 95 yr old chain smoker coughed up a lung.

 

[salvageV6]

That's the protective tar they used to "weatherproof" the connection.
It's not supposed to travel to the copper contacts of the relay itself however but often does.
More tar than nicotine.

 

[Anthony P]

relays and the bulkhead harness connectors at the firewall, for example had that permatex like stuff applied to the terminals to prevent corrosion. I'll try to post a pic tomorrow of the stuff dabbed on relay terminals. After many decades, the stuff has hardened to appear tar like.

 

[Dan SS2471]

I made it worse by trying to clean it with isopropyl alcohol which 'loosened' it up and it became a liquid mess. The CRC stuff cleaned it up nicely.

 

[scgnx2]

That's the protective tar they used to "weatherproof" the connection.
It's not supposed to travel to the copper contacts of the relay itself however but often does.
More tar than nicotine.

That’s what happened to my AC relay and Fuel pump relay on the passenger side front fender. That “tar” migrated into the contacts and created very high resistance on the power feed. They got so hot it melted the relay modules and they failed.
Casper Electronics has really nice pigtail replacements which have silicone gaskets to properly weather seal them.

 

[Anthony P]

pictured below are a NOS fan delay relay and an NOS A/C relay with that aviation permatex tar-like weatherproofing applied before packaging - date coded 1988 and 1994, respectively.

Since the contacts you cleaned are now bare, I'd suggest applying some bulb grease to the contacts/connector spades to keep moisture out. On the driver's side, there is no sheet metal cover for the relays like on the passenger side...unless you bought the aftermarket DS relay cover.

 

[Dan SS2471]

These are the ones I picked up. I like the LED as at least an indicator of the relay having power at the 12v pin. The rest when this kind of thing happens...time to test other things (like RYLS fuse) but in this case, just turned out to be faulty contact.