Radiator drain plug difference

[jsrnsis]

IMG_5264.jpegSo, small update to what I’ve found…..
The threads on the drain plug for the OE rad are in fact M12-1.75. However, the threads in the aftermarket rad are NOT M12-1.75. After reading your post, I sourced a M12-1.75 plug locally for this aftermarket rad and tried to put it in. It tightened up about two turns in and I didn’t force it out of fear of splitting the threaded hole. After pulling it back out and comparing with the broken drain plug, the threads are definitely different. I did mention that before about your original pic, that I thought the threads looked different, but I trusted your confidence and went with the M12-1.75 plug.
Maybe the fact you did it with plastic bolts made the difference, or maybe it’s a different aftermarket rad, I dunno….but after using a thread gauge I can 100% confirm that the threads in my aftermarket rad are not M12-1.75 like the OE Volvo rad threads are.
Back to hunting for the proper threaded plug tomorrow I guess……now starting to wish I just did the JB Weld suggestion…hahaha.

That adds some more mystery, as you have must have a third similar, yet repair-haltingly different radiator plug. The M12 1.75 threaded in perfectly fine to my aftermarket rad. Before JB welding, make sure the lower radiator hose clamp comes off easily. Worm drive clamps, especially one that exposed to road salt and spray, can still rust themselves together.

[TrevB]

Must be another different aftermarket manufacturer using whatever thread they saw fit. Nothing like making it difficult. Haha.
I found a Dorman oil drain plug with M12-1.5 thread, I cut it down to the proper length, removed the crappy washer it came with and added a rubber o-ring under the head. It screwed in and sealed perfectly.
We’ll finally call this one a win!