Chapter 7: Transmission
Automatic Transmission
After the engine, the transmission is the next most important part of the car & needs to be checked thoroughly. With your foot on the brake pedal, start the engine and move the transmission lever from Park to Neutral, then to Drive. It should take you about 0.5 seconds to 1 second maximum after you move the lever from neutral into drive until you feel a gentle nudge. Try the same test from Neutral to Reverse – it also should not take more than 1 second before the car begins to move. A longer delay and/or a clunking noise would indicate a transmission fault. Automatic transmissions are complicated, and generally any repairs are very expensive. During the test drive we are looking out for sudden sharp jolts while changing gear. Stop the car at the side of the road and check that all the gears are changing properly from standstill, counting them as you go. Stop again and repeat the test; you may begin to notice a particular gear change is jerky. Also check that there is no jerkiness changing down the gears while slowing down.
Drive at a steady 40mph for a while, then accelerate hard. The transmission should kick down into a lower gear, possibly second. This should happen fairly smoothly without any serious knocking or banging.
Check the oil in the automatic transmission by removing the dipstick under the hood. Clean transmission oil is red, while old oil will turn black. Smell the oil, and if it smells burned then the transmission oil needs to be changed and indicates a fault.
Automatic Transmission Summary
*Deal Breaker colums A, B & C refer to the following 3 cars: A – 10 Year Old Family Car E.g Toyota Corolla, B – 6 Year Old Mid Size, E.g Audi A6, C – 2 Year Old 4×4, E.g Honda CRV visit here for more details
Manual Transmission and Clutch
While stationary, with the engine running and gearbox in Neutral, depress the clutch pedal release and repeat two or three times. Listen for any extra whirring or whining noises. This would indicate a worn clutch release bearing. With the clutch depressed, select 1st gear. It should be easy to select without any drag or effort required. If 1st gear is hard to select, the clutch may need to be replaced.
While in 1st gear and with the clutch depressed, release the pedal slowly and drive off. The clutch pedal should have a smooth steady feel to it and the car should move smoothly. Any shaking or vibrations indicate that the clutch or pressure plate may need to be replaced. Change into 2nd gear and listen for any additional noises. Repeat throughout all gears. A damaged manual transmission can have a difficult-to-move gear shifter/lever or a whining noise while driving.
Some manufacturers have, in the last 10 years or so, introduced manual gearboxes which use a “floating flywheel” system. When the floating flywheel is beginning to fail, a rattle can be heard when the engine is idling in Neutral. As the flywheel progressively worsens, a vibration is felt while accelerating. The flywheel will eventually need to be replaced. This repair is expensive and labor-intensive, so do your homework on the costs and demand a large discount from the seller if you still want to purchase.
To confirm that the clutch is not slipping, find a gradient or a level section of the road and while driving at about 40mph in 4th gear, accelerate hard. The engine revs should rise slowly and in proportion to your speed. Keep an eye on the RPM level to make sure the engine is not revving high (i.e., above 4500RPM). If the engine revs quickly while driving without a rapid change in speed, the clutch is slipping and will need to be replaced.
Check for a clunking noise when the accelerator pedal is pressed and released several times. This could mean that the transmission and or prop shaft/differential is worn. There is not normally a dipstick to check the transmission oil level in a manual transmission.
Manual Transmission and Clutch Summary
*Deal Breaker colums A, B & C refer to the following 3 cars: A – 10 Year Old Family Car E.g Toyota Corolla, B – 6 Year Old Mid Size, E.g Audi A6, C – 2 Year Old 4×4, E.g Honda CRV visit here for more details
Constant Velocity (CV) Joints on Front Wheel Drive and Four Wheel Drive Vehicles
The outer CV joints are fixed to the end of the drive shafts and are located just behind the front wheels. When they fail a clicking noise is heard from the front. To test them, drive to a parking lot or open space. Turn the steering wheel fully to the right and accelerate moderately. Do the same for the left. A clicking noise will be heard which will disappear when you straighten the steering wheel up again. They are a regular maintenance item and fail when the rubber boot surrounding them splits and the joint, having lost the necessary lubricating grease, begins to click.
Constant Velocity (CV) Joints Summary
*Deal Breaker colums A, B & C refer to the following 3 cars: A – 10 Year Old Family Car E.g Toyota Corolla, B – 6 Year Old Mid Size, E.g Audi A6, C – 2 Year Old 4×4, E.g Honda CRV visit here for more details
Next;
Part 9 : Additional Test Drive Checks
Index
