Subaru Catalytic Converter

FAQs— Subaru Catalytic Converter

1. I know that I can’t work on my catalytic converter while the exhaust system is still hot. How can I properly test the temperature of the system for me to know when to start with my cat con replacement?

You can do that by wearing a heavy-duty mechanic’s gloves and, with the back of your hands, gently brushing the exhaust tube. If you can no longer feel any heat, try to repeat the test without the glove. Just be careful to avoid getting burnt. If it is still hot, let it cool down for a few more minutes before trying to test it again.

2. I was doing a DIY fix on my Subaru catalytic converter but I recalled that during the last time I had it replaced by a mechanic, it was welded in place. Is the job feasible for an amateur DIYer like me?

You can still do the repair by yourself even if the cat con is welded to the exhaust system at its connection points. However, you should make sure that you have access to a sawzall as well as a welding machine and you know how to use such equipment safely. Remember that these are advanced tools and may be beyond your mastery.

3. During troubleshooting, I noticed that my Subaru catalytic converter is bolted in place. However, the bolts have already rusted. Any tips on how to properly remove such bolts?

Partially corroded and rusted bolts or those that have jammed into the nuts can really be kind of difficult to remove. It helps if you loosen up the said bolts by putting on penetrating oil and allowing the oil to seep into the bolts so that it can lubricate them for a few minutes before you remove them using an appropriately sized wrench.

4. After installing my new Subaru catalytic converter, what are the easiest ways to check if my DIY task has caused exhaust leaks?

If you want to check for exhaust leak without physically getting under the vehicle and checking the pipe, you can drive test your ride and observe the exhaust behavior while you drive. If you notice that the car growls louder than usual or when it rumbles more than normal, there may be a leak in the system. Alternatively, you can jack up your ride, start it in park, and slowly move a lit candle along the length of the exhaust tubing. The flame will wave or blow out when it gets in front of the leak.

5. What can possibly happen if my Subaru catalytic converter gets backed up with debris, soot, and other byproducts of exhaust?

This can affect the engine's capacity to rid itself of exhaust, therefore causing a big drop in your vehicle's fuel efficiency. Worse, the soot and debris can make the engine stall. When this happens, perform a backpressure test. Such test can be done by screwing a pressure gauge into the oxygen sensor's slot on the converter. When the engine is operating at 2,000 RPMs, the pressure reading should be less than 1.25 psi. If there’s congestion, you’ll get a higher reading.

6. A friend told me that I can use a mallet to test my old converter. Is that true? If yes, how can I perform the test properly?

Yes, a rubber mallet can tell you if it’s already time to replace your old converter. With the rubber mallet, give your catalytic converter a firm hit. If there’s rattling from the inside, that means the converter now needs replacement as its metallic catalyst has begun to crumble and corrode.

7. Instead of replacing my dirty Subaru catalytic converter, can I clean it first? Is it worth a shot?

Yes, you can take the catalytic converter off your Subaru and try to clean it to eliminate the soot and debris that are causing the catcon to malfunction. You can clean it using compressed air or a catalytic converter cleaner. When using the former, you have to remove the core and use 90 psi maximum compressed air. This is enough to blow away ash, dust, and light accumulations. When using a catalytic converter cleaner, on the other hand, make sure to strictly follow the instructions that come with the cleaner for best results.