Modern automatic transmissions (automatic transmissions) are quite reliable components. And according to this indicator, they are not inferior to mechanical ones. It is not for nothing that the Americans equip all military equipment with automatic transmissions, and reliability is of paramount importance for military vehicles! And mechanics specializing in the repair of automatic transmissions claim that 95% of the breakdowns of this unit are due to non-observance of the operating rules. Despite this, the automatic transmission requires a particularly careful check when buying a used car.
Necessary
Test vehicle with automatic transmission only
Instructions
Step 1
An automatic transmission is a very complex device, consisting of numerous parts and seals. The wear of just one element leads to incorrect operation of the entire unit. Also, the automatic transmission is sensitive to overheating. Half an hour of skidding in deep snow is enough to burn a box. The oil in an automatic transmission should be changed more often than in a mechanical one, and the consequences of driving on "old" oil are more dire. The wrong choice of oil poured into the box can ruin it on the very first day of operation. In addition, the machines do not tolerate repair well and do not last long after it. Therefore, practical Americans and Europeans do not repair the box, but change the assembly assembly.
It should also be remembered that repairing an automatic transmission is very difficult and very expensive.
Step 2
Before checking an automatic transmission, it is helpful to find out the history of the car. This can save time and money. If the car was used for rent or was restored after a serious accident, the automatic transmission will not last long. The same can be said about the already repaired box. All automatic transmission repairs have problems. And not all workshops can professionally repair automatic transmissions. The presence of a tow bar on a car may mean increased wear on the machine caused by transporting the trailer.
Step 3
Checking the automatic box.
First, you should check the oil level in the box and its condition. In this case, the engine should run at idle speed, the machine selector should be in the "parking" position. The transmission dipstick is removed, wiped with a clean cloth and reinserted. Now you should pull out the dipstick again. To assess the condition of the oil, wipe the dipstick with white paper. There should be a clean and transparent mark on the paper without metal or foreign particles. The new oil is red in color. Not new may be brownish, but not black. And don't have a burnt smell.
It should be borne in mind that modern automatic transmissions do not have an oil dipstick. Checking the oil level and condition is possible only at a specialized technical center.
Step 4
Automatic transmission testing on the go.
The delay between the moments of choosing the position of the selector "D" or "R" and before turning on these positions of the selector is a sign of a defect. First, you should warm up the car and the box in the "P" (parking) position until the revs drop to 600-800. While holding the vehicle in place with the brake pedal, the selector switches to "D" (drive). The machine must immediately select this mode and start trying to drag the car forward. Everything should happen softly, without jolts and knocks. Further, when switching to "N" (neutral), the box should be disconnected. Now, when you turn on "R" (reverse), the automatic transmission should also turn on instantly, without clicks and knocks. The car should try to crawl backwards.
While holding the brake pedal, you should check the box, switching from "D" to "R" and back. There should be no jolts or knocks. Delay more than 1 sec. when any mode is turned on, it indicates wear or damage to the box.
Step 5
For further check of the box on the go, it is necessary to develop the speed up to 50-60 km / h. Gears must be switched at least twice, softly, without jerks and delays. The fact of a gear change is determined by a slight change in engine noise and a drop in engine speed. With excessive wear of the automatic transmission, a jolt, delay or shock is felt at the moment of switching.
At a speed of 40-50 km / h, you should drown the accelerator pedal all the way. A properly operating machine will downshift and the engine speed will increase.
If there is an overdrive mode (the button to the left of the automatic transmission selector on Japanese and American cars), it is also checked. To do this, at a speed of 60-70 km / h, the ON mode is turned on by pressing the overdrive button. The gear should shift up one. When overdrive is disengaged, the gear shifts one down.
The problem of slipping gears looks like this: when the gas pedal is pressed, the revs increase, but the speed does not increase.
