All piston engines between 1978-82 have a canister at a different point to the air cleaner in the engine compartment that must be inspected to ensure there is no fuel or activated carbon leakage and tapped lightly to determine internal looseness. In case any leakage or rattling has been observed, it should be replaced by unscrewing the hose clamps, taking out the hoses, unbolting the unit, and following the same procedure to install it back. The frequency of inspections is supposed to be 25,000 miles (40,258 km) or 24 months. In the case of 1983-85 GLC models, inspect the leaking charcoal and rattle; in case of problems, change the part. Open manifold vacuum, idle engine, and ensure air is free to flow through port B, otherwise change canister; also remove hoses away at port A. On 1983-85 626 models, detach the air cleaner assembly, stuff in some hoses and verify that there is suction at the bottom of the canister when the engine is hot. In the absence of a suction, confirm the vacuum at the purge valve, otherwise examine the problem of vacuum hose. Disconnect the vacuum sensing tube to provide slight resistance otherwise, change canister. Checks of canisters are not required except in the case of 1986-89 323, 626, MX-6 and 929 models unless there is evidence of fuel leakage or idling problems. In RX-7 models of the 1979-80, the fuel cleaner assembly has the charcoal canister in the air cleaner which absorbs the fuel vapor when the engine is off. When checking air filters take inspection of oil or gasoline saturation, vacuum gauge testing of the canister should be done, where the reading of 2.36 in Hg to 0 at 2,500 rpm is the indication of the canister blockage and thus requires replacement of the complete canister/top cover assembly. In the case of RX-7, (1981-1989) inspect the standard charcoal canister visually in 1981-89 to ensure that the canister is carbon stained or leaking and tap to ensure that the canister is not rattling, indicating that the canister needs replacement.