Root cause is always a necessary evil. We have an A&P in our group and we asked him about that. Apparently the oil cooler came off a scraped Ercoupe and was not tested. The annual is due in Feb so the trashed oil cooler will be replaced with a new PMA part with an internal by-pass valve. The club voted not to go cheap this time. We're in the Southwest desert so the engine requires an oil cooler during the summer time. I flew it yesterday, thanks to Skyfixer's comments, and the temp stayed around 180F.