Case Seal Gasket, Leybold Trivac D2A/AC D4A/AC, Part# 23811123 – vacstellar

It’s a direct replacement for the original Leybold part, so it drops right in. Just clean the mating surfaces, lay it in place, and bolt everything back together.

If you’re rebuilding one of these pumps, don’t skip this gasket. It’s cheap, easy to fit, and makes a big difference.

This is the largest gasket that seals the whole pump case.

It sits between the pump body and the oil reservoir. Without a good seal here, oil can leak out and the pump loses performance.

You’ll find this exact gasket in almost every major repair kit for the D2A, D4A and S4A series (including the AC versions). Technicians usually replace it whenever they open the pump for a full service.