Re: The engine ran great!!!….except when it didn’t. Home › Forum › Ask A Member › The engine ran great!!!….except when it didn’t. › Re: The engine ran great!!!….except when it didn’t. sutterhomeReplies: 36Topics: 2 September 4, 2018 at 3:17 pm #82268 Don’t the old pressure tanks have a relief valve in them.The last one i messed with did.