Can't say for sure if it would work safely for what you need but we have had some very good luck with epoxy products like JB Weld, JB Quick weld, Steel Putty, etc. If you cleaned the plug good with something to take the oil residue off then used some JB quick Weld to put it in place it might do the trick. Be sure whatever is behind that plug will not cause problems if some of the epoxy gets in there. If it is just a plug probably no problem but if it happens to be a passage or some moving part inside there it might not be a good idea. That is your judgement call.

We blew out the pipe fitting on the aluminum intake manifold on our Eagle sp sprayer while in the field a few years ago. Like you we needed a quick fix to get the load off that day and finish spraying that week. Used one of the steel putty expoxy (I think this particular tube we got at NAPA, we also buy from Walmart) products around the pipe fitting threads and built up some reinforcement around the area - been going ever since and have no plans to fix it otherwise. Have repaired lots of other stuff. Often successful, sometimes not but if in a pinch worth a try.

John