Top 3 Reasons Honda/Acura Transmissions Are Failing
Automatic transmissions on some Honda and Acura models have a deserved reputation for unreliability. Although the majority of the failures were in cars manufactured between 2000 and 2004, later models do experience problems and you should never ignore warning signs of potential transmission problems. A number of factors cause the transmissions to fail.
Failure of the Torque Converter Clutch Lining
The torque converter is fitted with a lock-up clutch that locks the converter to give a direct drive once your car is up to speed. These clutches have linings made from a material that has a poor resistance to excessive heat.
If the transmission oil overheats when under heavy load or due to poor cooling, this lining becomes glazed and the clutch starts to slip. This in turn leads to further overheating of the transmission oil to the point when it starts to break down. Once this occurs, the debris from the burnt oil and damaged clutch lining clogs the filter and solenoid valves, leading to poor operation of the box and ultimately failure.
When Consolidated Vehicle Converters rebuild torque converters, they overcome this problem by using a high specification Kevlar and carbon lining that can safely handle high temperatures and loads.
Pressure Regulating Valve
Proper operation of the pressure regulating valve is essential for reliable operation of the gearbox. If the valve is out of balance, there is inadequate flow of transmission oil to the torque converter, causing slippage and glazing of the lining.
The valve is controlled by a strong spring balanced against hydraulic pressure on the other end of the valve. This valve has a tendency to stick in a partially open/closed position, limiting oil flow to the torque converter, lubrication, and relief valve, especially at low speeds where the oil pump flow and pressure are low.
This problem is exacerbated if the transmission oil is contaminated by overheating, contains debris from damaged clutch linings, or worn out from missed transmission oil changes.
Consolidated Vehicle Converters recommend the fitment of a modified Sonnax valve with an internal relief valve that ensures flow of oil to the torque converter at low speeds without affecting performance under normal conditions.
Faulty Operation of Clutch Pressure Control (CPC) Solenoid Valves
These valves control gear selection; in the Honda there are two for a four-speed transmission and three for a five-speed.
Smooth operation of these valves is essential for smooth gear changes. Unfortunately, they have a tendency to snag and not open completely, which results in the wrong oil pressure on the clutch cylinders.
If the pressure is too low, the internal clutches slip and if it is too high, gear changes are harsh and jerky.
What to Do
Does your vehicle experience any of these symptoms?
- Racing engine during up-shifts
- Slow take off
- Sluggish gear selection
- Harsh gear changes
- Engine warning light illuminating
Don't ignore them; they will not go away, even if you change the transmission fluid. Have your transmission checked. If you act promptly you may save a lot of money and avoid a transmission replacement.