Hello Peter
The glow plug relay fuse is intact.
In the many hours I have been on the phone assisting, this has been at best a secondary issue; getting fuel to the injectors has been a trial of nerves.
The engine oil cooler lines have been cut in half (by the PO?), my guess is to R&R radiator in the past, the splice is ½ inch copper tube and standard worm gear clamps.
The engine started for a couple of seconds, the splice failed and spewed engine oil, no damage to engine, but a large mess.
The lines are going to a local hydraulic shop for repair.

Now that I am not occupied with immediate fuel and compression concerns, it seemed the perfect time to update and ask for suggestions on the glow plug relay problem, before I start 1985 300SD Sady down the electrical diagnostic path.

Yes, please send the complete diagnostic of the glow relay.
I have kept 1985 300SD Sady very busy rerouting and repairing.
Injector bleeding took over eight hours of real time, chasing off to get a new battery and a 50 AMP charger didn’t help job time.
The light dawned very bright when I realized that out of zeal to follow advice, 1985 300SD Sady had disconnected the ALDA also.

Hello Brian
I don’t know if there is power from the key switch to the relay.
The diagnostic will not begin until Tuesday.
1985 300SD Sady did confirm zero volts to glow plugs and order a used relay, trusting the PO’s diagnosis, before I was involved.
Wiring issues are more possible than what I like on this car, 1985 300SD Sady has described some of the dash and radio console wiring to me.

I know about the oil breather can and agree, it is a best possible repair in budget, the OEM housing and T bracket are wrecked by fractures and chunks missing.

Thank you all.
whunter