I refer to 1983 Mondial Parts Catalog, Table 15: I think the 1983 model was the last year of the 8 “analyzing pipes” - little tubes that allow easy analysis of exhaust from individual cylinders. Those tubes corroded and eroded over time, so I had the tubes removed and the 8 holes in the exhaust two manifolds plugged. The plugs are screw-in M12 x 1.25 drain plug type. It as not stainless. Bolt shaft is 20mm long. Unfortunately, over the last two years two plugs have “left the building.” It appears copper crush washers were used; the copper melted; the plugs backed themselves out over time via heat expansion/contraction and vibration. That is my guess. It is clear I need to check each plug from time to time and retighten if needed. Perhaps stainless steel crush washers should be used. How are other FChatters plugging these exhaust holes? SG Sent from my iPhone using FerrariChat.com mobile app
Even the factory used copper crush washers on exhaust plugs on cars with cats so that is not the issue. I'd suggest just making them tighter.
110860 is the more official F part: https://www.ferrariparts.co.uk/part/ferrari/110860?id=82064 but still uses a copper sealing washer (yours probably just vibrated loose and fell out -- 20 mm seems a quite long threaded length and those plugs may be bottoming out rather than clamping the copper washer at the top).
For timeline - the old, small “sniffer tubes” were removed and plugs inserted about eight years ago. Sent from my iPhone using FerrariChat.com mobile app
Update: I checked the available depth below the 20mm plug. The plug didn’t bottom out. I obtained the proper stainless plugs - threads are to be lightly coated with copper (anti-seize) grease and I will also install copper washers. I don’t know proper torque but I will tighten without stripping. Anyone know torque? The stainless plugs (about 12 mm long) have a hole drilled into the threaded base. My guess is that hole helps the plug to expand laterally with heat rather than longitudinally. The installed “general purpose” plugs might be affected longitudinally by repeated exhaust temps and then cooling. If true - they might tend to back themselves out. Got to check even the new proper stainless plugs too to make sure. Reminder - this situation only applies to those Mondials/308s with the eight exhaust sample tubes. Mine is an ‘83. SG Sent from my iPhone using FerrariChat.com mobile app
