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ENGINE - On-vehicle Service 11A-13 (2) If there is a problem with the lash adjusters, the noise will almost never disappear, even if the engine has been run at idle to let it warm up. The only case where the noise might disappear is if the oil in the engine has not been looked after properly and oil sludge has caused the lash adjusters to stick. 1. Start the engine. 2. Check that the noise occurs immediately after the engine is started, and that the noise changes in accordance with changes in the engine speed. If the noise does not occur immediately after the engine is started, or if it does not change in accordance with the engine speed, the problem is not being caused by the lash adjusters, so check for some other cause of the problem. Moreover, if the noise does not change in accordance with the engine speed, the cause of the problem is probably not with the engine. (In these cases, the lash adjusters are normal.) 3. While the engine is idling, check that the noise level does not change when the engine load is varied. If the noise level changes, the cause of the noise is probably parts striking because of worn crankshaft bearings or connecting rod bearings. (In such cases, the lash adjusters are normal.) 4. After the engine has warmed up, run it at idle and check if any noise can be heard. If the noise has become smaller or disappeared, oil sludge could make the lash adjusters stick. Clean the lash adjusters. (Refer to the Engine Workshop Manual.) If not improved, go to step 5. 5. Bleed air from the lash adjusters. 6. If the noise has not disappeared even after the air bleeding, clean the lash adjusters. (Refer to GROUP 11B - Rocker Arms and Camshaft.) <LASH ADJUSTER AIR BLEEDING> NOTE (1) If the vehicle is parked on a slope for a long period of time, the amount of oil inside the lash adjuster will decrease, and air may get into the high pressure chamber when starting the engine. (2) After parking the vehicle for long periods, the oil drains out of the oil passage, and it takes time for the oil to be supplied to the lash adjuster, so air can get into the high pressure chamber. (3) If either of the above situations occur, the abnormal noise can be eliminated by bleeding the air from inside the lash adjusters. |