I've tried four of these and NONE hold a vacuum, each turning my vacuum pump on at different intervals. For some, the pump stays on, for others, it turns on every 20-30 seconds. One of them I tried started the pump about every 10 minutes. I will not wear out my pump and change it too. If I disconnect this part and cap the lines, the system will hold a vacuum overnight or longer. Now I'll go with the factory part.