Contents: Preliminary checks ⇓ Fluid leak diagnostics ⇓ Leaks through gaskets ⇓ Leaks through seals ⇓ Leaks through the housing ⇓ Fluid leaking through the vent or…⇓
Note: Automatic transmission failure can occur due to the following five main causes: poor engine performance, improper adjustment, hydraulic system failure, mechanical failure, computer failure, or electrical wiring failure. Troubleshooting should begin with easily remediable causes, checking the fluid level and condition, adjusting the shift cable and selector position sensor. Then perform a road test to make sure the problem has gone away or not. If the cause of the malfunction is not eliminated, further troubleshooting is best performed at a service station. Read the paragraph "Troubleshooting", given at the beginning of this Guide.
Preliminary checks
1. Warm up the transmission fluid to operating temperature (take a short trip).
2. Check the transmission fluid level (see chapter 1):
- a) If the fluid level is low, add fluid to the normal level. then find and fix the fluid leak (see below).
- b) If the fluid level is too high, drain the excess fluid and make sure there is no coolant in it. The presence of coolant in the transmission means a breakthrough in the walls of the transmission heat exchanger in the radiator (see chapter 3).
- c) If the fluid has foamed, remove it and add fresh transmission fluid. Make sure the fluid level is not too high and that there is no coolant in the fluid.
3. Check the engine operation at idle speed.
Note: If the engine is faulty, suspend further checks until the engine fault is corrected and then perform all preliminary checks from the beginning.
4. Make sure that. that the throttle cable has free movement.
5. Inspect the transmission control drive (see paragraph 4). Make sure it moves smoothly and is adjusted properly.
Fluid leak diagnostics
6. Most leaks can be detected by simple inspection. To fix the problem, it is often enough to replace the seals or gaskets. If the fluid leak is difficult to detect. The following procedure may help you with this.
7. Determine what liquid is leaking. Make sure of that. that it is transmission fluid, not engine oil or brake fluid (transmission fluid is usually dark red in color).
8. Try to pinpoint the exact location of the leak. Drive a few kilometers, then park the car over a large sheet of cardboard. After 1-2 minutes, there should be spots left on the cardboard that will help identify the location of the leak.
9. Inspect (very carefully) the heated component and everything around it. Use a mirror if necessary. The most likely places for leaks are the gaskets at the joints of parts.
10. If the leak location still cannot be determined, wipe the suspected areas with solvent and dry them.
11. Drive for a few kilometers with the engine and transmission warmed up. change gears, then inspect the suspect component again.
12. Once the leak location is located, determine the cause before repairing it. If you install a new gasket on a warped flange, it will not help. It is necessary to correct the flange deformation.
13. Before repairing the leak, make sure the following conditions are met. Otherwise, fluid leakage may reoccur in this or another location.
Note: Some of the following conditions cannot be tested without special equipment. These problems should be addressed at a service station.
Leaks through gaskets
14. Check the tray periodically. Make sure all bolts are tight and in good condition, the gasket is in good condition and the pan is not damaged (dents in the oil pan can damage internal transmission components).
15. If a leak occurs through the oil pan gasket, this may be caused by overtightening the oil pan mounting bolts. damage to the joint surfaces, damage to the gasket or a crack in the gearbox housing. If a seal was used instead of a gasket, it may not be the correct type.
Leaks through seals
16. If a leak occurs through the transmission seal, it may be caused by a high fluid level, a clogged vent, a damaged seal or improper installation, damage to the shaft surface or shaft bearing support (excessive bearing play may lead to leakage through the seal).
17. Make sure the fluid level dipstick tube seal is in good condition and fits securely. Periodically check the area around the speedometer or speed sensor drive. If a leak occurs, check the sealing ring for damage.
Leaks through the housing
18. If a leak occurs through the housing, the housing must be repaired or replaced.
19. Make sure that. that the oil heat exchanger hose fittings are securely tightened and in good condition.
Fluid leaking through the vent or filler neck
20. If this happens, it means that the transmission fluid level is too high (this may be due to the presence of antifreeze in the fluid), there is a crack in the crankcase, the dipstick is faulty, the ventilation ducts are clogged.