I was thinking about replacing both, but I'm not sure if the other one will come out easily. I think that these are less like the domed-disk Welch plugs and more of a slug of metal, ~7/16" deep. I won't know for sure until I see the new one.
When you did the rebuild, how was the block cleaned? Caustic dip? Ultrasonic? Boiled? If one came out, I'd fret that the other would too. But if you go to take it out by whatever method (drill, tap, slide hammer as an example) and it won't come out, then what?
(My family crest says "super cogitare super aedificare".)
Gee, it's been so long that I can't remember how it was cleaned. Perhaps I'll call that shop later today.
I don't want to booger up the existing plug just to find that it is stuck fast in there. I think that I'll play around with it to get an idea if it is loose or not. If there is any kind of play in it, then I will definitely press in a new one. Regardless of whether I replaced one or both plugs, I'll use the flange sealer that interalian recommends. I suppose that I should simply use an appropriately sized socket and tap it into place?
I'm thinking that cogitare is the latin root for cognition (thinking) and aedificare is the root for edifice (building). Is that correct? And the entire phrase taken together with the other modifiers means...?
Gee, it's been so long that I can't remember how it was cleaned. Perhaps I'll call that shop later today.
I don't want to booger up the existing plug just to find that it is stuck fast in there. I think that I'll play around with it to get an idea if it is loose or not. If there is any kind of play in it, then I will definitely press in a new one. Regardless of whether I replaced one or both plugs, I'll use the flange sealer that interalian recommends. I suppose that I should simply use an appropriately sized socket and tap it into place?
I'm thinking that cogitare is the latin root for cognition (thinking) and aedificare is the root for edifice (building). Is that correct? And the entire phrase taken together with the other modifiers means...?
I was just throwing the 515 sealer out as an example, but it does form an extremely good bond. There may be other, more suitable sealers. A specific one would be for casting/core plugs on car engines. Check your local autoparts place for their reccy.
As for causing the overheat, I would say that the missing core plug did dump water out of the cavity between the crankcase and exhaust, so you lost most of the water that should have been there to go around the STBD cylinders, dumping it out the exhaust instead. You're lucky you found the problem before the water farked your motor with rust or hydrolock.
Success! I installed the plug and used some Loctite. Now the t-stat and cooling system are acting properly, spitting a small amount of water when the engine is running cool, and quite a bit once the water heats up from recirculation through the system. What a doozy of a problem this was.
The engine still seems to be running hotter than perhaps it should based upon some forum posts that I've read. But it is indeed working in terms of the t-stat valve staying closed until a threshold temp is reached, then dumping the too-hot water and replenishing with cool river water. Perhaps it's just a hot runner. A video of a cool-hot-cool-hot cycle can be found here: https://drive.google.com/open?id=0B8xDd3fDFA6xWnE1RWtZYnhmanM
Warning: the video shows two complete cool-hot cycles with temperature and the exhaust port clearly visible; it is a large video file and is about 3 minutes long.
