Going from memory here. Early either Positech or Setrab oil coolers being defective. I seem to remember that the issue was with the inside diameter of the cooling tubes either being too small or too turbulent to allow proper flow and heat transfer. I remember that a number of folks bought them and ended up having them replaced by the manufacturer. I tried to do an advanced search for this but the oldest thread that showed up was 2005. Does anyone remember which brand it was? What models were affected, & what serial number range was affected? I seem to remember the issue being mostly with Builders using the angle valve 360 engines.
Charlie
Charlie