Check Valve
Remove check valve and attach vacuum gauge to White side (EFE side) of valve. Attach vacuum pump to other side and draw vacuum. With pump removed there should be no leakdown. If so, replace valve.
Remove check valve and attach vacuum gauge to White side (EFE side) of valve. Attach vacuum pump to other side and draw vacuum. With pump removed there should be no leakdown. If so, replace valve.