My 2008 Prius has 165,000 mi. A few months ago, prior to AC season, the engine started running a bit louder than it had been. I'm only getting 39 MPG. The following were checked and are good: tire pressure, oil level, coolant levels, air filter. I'm thinking maybe changing the transmission fluid or both coolants. Which one would be causing the louder-than-normal engine?
Back in January, some light-fingered, slimy shyte-for-brains stole ChugyPyg's catalytic-converter and the immediate effect on the noise-level of the running engine was quite noticeable. There was a rash of such crimes in this area back in January. It's 3 am. Do you know where your catalytic-converter is?
How much louder? Like really loud? Or just sort of loud? And as per @bisco comment... Does it smell like an old 1970's car in the engine compartment when engine is running?
Alittle louder but noticeable from what it had been. Cat. converter is OK. No smell from the engine compartment. MPG down to 36.
On the screen Energy Monitor, under Battery, the green bars are at about 90%. The blue bars at 80%. MPG are now down to 36.
you would have to start with the manifold, feeling for escaping air, and work your way back to the muffler
Get a length of small hose (around 1/4" diameter, maybe 3 foot long). Hold one end in an ear while carefully moving the other end around exhaust system parts. When you get the hose near a leak, it will sound much louder . You need to keep the engine running. You can put the car in "maintenance mode", or try turning the heater up to hi-full hot. You need to safely raise and support the front of the car to be able to check everything- especially the spring loaded flex joint between the exhaust manifold and the catalytic converter. The "donut" gasket can wear and leak. If so, get a new one from Toyota- that fits and seals best. It can help to have a helper use a heavy leather glove to "cap" the end of the tailpipe and force more exhaust out of any leaks - do that for a few seconds at a time then pause so you don't get a burned hand. Posted via the PriusChat mobile app.
Update- I usually drive with the windows up hence the noise seemed to be coming from the engine. One day with the windows down I realized the noise was coming from underneath the car. In short, cat converter was on its way out. Replaced it. About $1000, ouch.
Surprised you found the OEM cat it’s been on back order for a long time last I heard. Hope you didn’t pay $1000 for an aftermarket $125 cat. Cost $80 to weld it up.
