Pic. 6.13. If the transmission fluid level is low, look under the vehicle. Oil stains on the case of the automatic transmission will indicate the cause of the leak
1. In case of any automatic transmission failures, first check the transmission fluid level (pic. 6.13).
2. During a test drive, check the switching points. For this, the service station has special tables.
3. Proper adjustment of the linkage system between the automatic transmission and the accelerator is an important component of proper operation.
4. Measuring the working pressure of the pump, regulation and modulation pressure is a task for specialists. Some pressure values can be adjusted.
5. For a correct assessment of the switching process, the idle speed must correspond to the norm.
Checking the switching process
During trips, pay attention to the automatic transmission: whether it works correctly. The shifting process gives an idea of the state of the unit.
Upshifting. When you partially press the accelerator pedal, the gear change is not very noticeable. In mode «full throttle» («Kick-down») shifts are more noticeable, but the upshift is still smooth. A short spin-up of the engine to high speed when switching indicates a possible violation.
Downshifting. Downshifting should be barely noticeable at low speeds (foot removed from the accelerator pedal). A jerk when forced down shifting with the accelerator pedal fully or partially depressed is normal. Switching down with the selector lever with the accelerator pedal released occurs with a delay of 1–2 s. If, when forced downshifting with the selector lever, simultaneously add «gas», the switchover will occur without delay.
Checking the oil level in the automatic transmission
The check is usually carried out after an oil change or if a leak is suspected. The prescribed oil level in the automatic transmission is very important for its perfect operation, therefore the check should be carried out with particular care:
1. Low oil level the clutches do not close tightly enough and slip because the hydraulic oil pump entrains air. The resulting foam formation causes premature wear of automatic transmission parts. In addition, the oil decomposes, becomes resinous, and a precipitate forms in it.
2. With an increased oil level there is increased contact of the oil with the parts of the gearbox, which is why it overheats. This leads to the same consequences as when air is sucked in due to a low level.
The transmission fluid filler is located in the engine compartment. Through it, using a dipstick, the fluid level is also checked.
Sequence of work
1. Apply the parking brake and move the automatic transmission selector lever to the position «P».
2. Start the engine and let it idle for 1-2 minutes.
Pic. 6.14. Checking the oil level in the automatic transmission: 1 - dipstick for checking the level of transmission fluid (located on the rear right side of the cylinder head); 2 - closing clip
3. Remove the closing clip 2 (pic. 6.14) above dipstick 1, pull out the dipstick and wipe it with a lint-free cloth.
4. To measure the level, insert the dipstick with the marking towards the rear (then when the probe is pulled out, the reading will not be smeared).
5. At the operating temperature of the automatic transmission (around +80°C) the oil level must be between the marks «MIN» And «MAX».
6. At an automatic transmission temperature of about +25°C, the oil level must be at least 12 mm from the mark «MIN».
7. Check the condition of the oil by color and smell - both signs make it possible to judge the condition of the automatic transmission.
8. Add gear oil if necessary. Its quantity should not exceed the prescribed level. The volume of oil between two divisions is 0.3 liters. In case of overflow, pump out or drain excess oil.
Transmission oil condition
1. Clean, red color - the condition of the oil is normal.
2. Burnt and darkened - the clutches are burnt. The automatic transmission must be replaced, the oil lines and the oil cooler must be flushed.
3. The presence of solid particles in the oil (metal particles) - The gearbox needs to be replaced.
4. Resinous and sticky oil - The automatic transmission was often subjected to overheating. Dismantling and reassembly required.