Pilot light keeps going out old Timken natural gas (standing pilot) chimney vent boil

jeffa_2

I’m working on a 60-70 year old Timken cast Iron natural gas standing pilot chimney vent boiler. 

The call was for the pilot going out. 

I’ve replaced the typical items. First the thermocouple, when that didn’t work, I replaced the gas valve….seemed to work for a couple days then off again?? Next I replaced the pilot assembly (which was ancient) and just in case I swapped out the thermocouple for a new one. Thought I had it licked…customer called again it went out. 

Now the only thing I can say that may or may not be an issue is there’s a very slight leak (only when the boiler is cold) that drips down the cast iron “next to” but I don’t think “on” the pilot assembly. The drip stops literally as soon as I relight the pilot and turn on the boiler. 

I thought about pouring in some boiler sealant to stop the leak, but I really don’t think that’s putting out the pilot 

I don’t know what else to do? 

Any ideas? 

jeffa_2

Oops my bad, mixed up these jobs 
I’ll get back with the correct boiler and pictures