I've mostly finished with my front power window work on the motors and regulator, and have started to figure out how to refurbish the tiny relay contacts.

Do any of y'all have any experience or suggestions on how to ' burnish ' the contacts? To me, I can't think of a way to reliably polish the contacts due to their size and accessibility.

I was able to order the same relays from Europe about a year ago. Do any of y'all have knowledge on how to solder ' without burning the circuit board '. the relays ' to me ' would soak up most of the heat before a good solder connection was made.

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If the contacts are burned, they're junk. Replace the relay.

If the contacts are just oxidized, use a piece of heavy cardstock soaked with silver cleaner and draw through the contacts while gently squeezing them together. Rinse with acetone to remove ALL traces of oil.

If replacing the relays, use a heavy soldering iron, 40W or better (80W if the cheap PTC kind you just plug into the wall). Preheat the copper lug from the relay with the tip, then flow solder onto the pad. Use 63/37 or 60/40 solder. Lead-free solder *WILL* break in applications like this.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Guess I could try the stem of a paper match, that might be small enough. I'll try the silver cleaner first and might try gluing fine sandpaper strips to the match stem for polishing. Thanks for the silver cleaner tip.

The tiny points are recessed in plastic so not much clearance for good access.

I spent a lot of time learning soldering in my early days with IBM but the components were much larger 60 years ago. We could pull most of the logic relay contacts out and polish them with a pencil eraser.

Be aware that the plating on the contacts is very thin, avoid abrasives if you can help it, you can burn right through to the brass which will then fuse together. If the contacts are already heavily pitted or ablated, they're junk so don't waste your time.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I've been researching soldering a bit,

do you think a small propane torch to heat the metal body of the relay would allow the solder to be sucked out from the circuit board through holes?

I have no experience with the small torches used for soldering. But it does seem that would reduce the heat time for the through holes and lands.

I've also thought of trying to cut/trim/nip the relay to reduce the amount of metal to be heated. Tried a normal sized dike pliers but not enough bite to cut the metal body. If most of the body was cut away before heating, less heat time and less chance of damage.

Any tool you can think of to 'cut' chunks out of the relay without damaging the through hole area?

As usual, you're way overthinking this. A torch will destroy the printed circuit board nearly immediately. Stick to a pencil iron if you're resoldering. You still haven't said why you're doing all this, if the points are oxidized, just clean them and get on with life.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Overthinking has worked out quite well for me more than once. It's easy to be a specialist if you study a great amount of time & then think about what you've seen. I avoided maiming surgery that five surgeons said I needed by spending a few months reading on uptodate.com. I would have been a cripple and probably dead by now if I had done what was ' the standard of care ' voiced by each of them.