Oil cooler burst when immediately after starting the engine. It was a coold day. Sonex technical assistance advised that this can happen if the engine is not preeheated when the weather is below 40 degrees. The also said it is possible that the control valve or the releif valve could be stuck.
I orderd a new cooler. I removed the releif and control valves and polished them to remove any chance that they would stick. to remove them Ifirst tried a magnet wich did not work well. After doing some research I found the better tool was a piles of aluminum tubing wich fit inside th valves open bottom. The alluminum tubing was slightly crimped (with a table vice) to make it a tight fit into the bottom of the valve so that it woud grab the valve.
To avoid bursting the new cooler I optes to buy and use a new cover plate that eliminated the oil cooler. This was a temporary plan just to get me through some engine and taxi testin during the cold months. The new cooler was later installed.
