Join Date: Nov 2001
Location: Chino Hills, CA
First, find the purge valve. It mounts on the firewall about 6" from where the AC lines go through.
Second, next time the knocking starts, pull over, open the hood, and TOUCH the purge valve. If the knocking sound fits the same pulseation of the purge valve, you've got it.
Other than that, it might be a motor mount. The motor mount on the drivers side gets grenaded from the exaust heat and will make similar noise. It is impossible to check it without removing it, but if you have 60K+ it's probablly done for.
1996 XJ Sport - Old Man Emu Springs and Shocks - Banks Stainless Header - BFG Tires - Wilderness Roof Rack - 250,869+ miles, one owner........