Oil tank

Besides the problem with the oil overflowing into the catch can, the top of the oil tank was leaking. This was making a big oily mess at the back of the car. It was requiring a lot of time and paper towels to cleanup after every session.

Removed the oil tank, plugged the lines and added some cleaning solvent and turned it upside down. The solvent leaked out at the cap.

Sure enough, their was a hole that someone drilled as a vent. In this application you don't need a vent hole. In fact the idea is not to let oil leak onto the track. That is what the catch cans are for. To hold excess liquids.

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Soldered the hole closed, this should stop the leak.