How long should the three-way catalytic converter be soaked in oxalic acid?
3 Answers
Soaking the three-way catalytic converter in oxalic acid for 30 minutes to 1 hour is sufficient, ensuring all areas are evenly soaked to avoid uneven treatment. The three-way catalytic converter transforms harmful gases such as carbon monoxide and hydrocarbons emitted from vehicle exhaust into harmless gases through oxidation and reduction reactions. When high-temperature exhaust gases pass through the purification device, the catalyst in the three-way catalytic converter enhances the activity of the harmful gases, promoting oxidation-reduction chemical reactions to purify the vehicle exhaust. Oxalic acid soaking can be used to remove rust from the three-way catalytic converter. However, caution is required as oxalic acid is highly corrosive to stainless steel. High-concentration oxalic acid can also easily corrode the skin, and the resulting acid oxalate salts are highly soluble and somewhat toxic. If skin comes into contact with oxalic acid, it should be rinsed with water immediately.
I remember the last time I cleaned the three-way catalytic converter myself, I used oxalic acid solution and soaked it for about 45 minutes. At that time, there was a problem with the car's exhaust pipe, and the exhaust gas smelled bad. I guessed it was clogged. Oxalic acid can dissolve some deposits, but soaking for too long can corrode the precious metal coating of the catalytic converter, which would be troublesome. Generally speaking, 30 minutes to 1 hour is relatively safe, depending on the degree of clogging: 20 minutes is enough for minor cases, and for severe cases, don’t exceed 1 hour to avoid damaging the parts. I wore gloves and goggles during the operation because oxalic acid is quite dangerous and can harm the skin if mishandled. After soaking, I thoroughly rinsed it with water, reinstalled it, and tested the car—it was indeed effective. I recommend checking fuel quality regularly and avoiding low-quality fuel to reduce such problems. In short, DIY can save money, but safety comes first. If you don’t understand, seek help from a professional shop.
As someone who frequently deals with automotive emission systems, I recommend controlling the oxalic acid soaking time for the catalytic converter to around 30 minutes. Too short a duration won't thoroughly clean it, while exceeding one hour may cause internal corrosion or failure of the converter, affecting emission control. The key is to first assess the clogging condition: 20 minutes of soaking is sufficient for mild carbon buildup, while severe cases can be extended to 45 minutes. However, always check if the oxalic acid concentration is appropriate and rinse with a high-pressure water gun afterward. This reduces risks since catalytic converters are precision components and improper handling can easily damage them. In practice, I've seen cases where prolonged soaking led to part failure, which wasn't worth the cost. Additionally, using a diagnostic tool to test emission values can better ensure effectiveness. For prevention, regular maintenance and high-quality fuel are recommended.
