Scion xA at 40K develops death rattle during idle

I’ve owned many 4 cylinder engines so know how vibration and rattles develop as the car ages. I’ve always been able to fix them or reduce them to an acceptable level. However my Scion xA has developed what sounds liked a death rattle at 40K. Of course shifting to neutral lowers the rattle volume substantially, but this defeats the purpose of an automatic and it puts your life in danger in California if your car is not moving into the intersection one microsecond after the light changes. I know everyone is pointing to me and saying “listen to that miscreant, you know it has to be his fault because Toyotas don’t make noises like that!” Do you know what a loss of face this is to an engineer and the son of an auto mechanic! Even my Audi 5000 couldn’t come close. Steven’s Creek Toyota of San Jose said it is a standard problem with the car, and can’t be fixed, and suggested a new car–in this economy! Any suggestions besides installing counter rotating shafts? Toyota appears to have tried to isolate the air/fuel plenum from the engine vibration. I’m electrical, but suspect vibration frequencies and damping components have changed with age so it no longer works as intended.


Don Chicoine


Scion sprouted from Toyota, but the cars are NOT Toyota built!

If idling in neutral vs. idling in gear changes the noise, there may be something in the accessory drives that resonates (vibrates) at the slightly different (higher) RPM in neutral.

Scions are not Toyota built? They are in fact built in Japan, by Toyota…

Are you sure that it isn’t a simple heat sheild/exhaust vibration noise? These vary with engine RPM. I had a Scion xB that developed a heat sheild vibration.

have you replaced any parts? alternator, serpentine belt? tensioner? anything running off the flywheel?

has your car been in an accident? had any motor mounts replaced? or other suspension work done?

After just again looking and listening with the transmission in Drive and the emergency brake on, I realized it really is a rattle like something loose or broken, not the typical drive train vibration being transmitted to the body/chassis. It is an isolated, loud, localized rattle seeming to come from the “Mass Air Flow Meter Assembly.” If the Mass Air Flow Assy is tapped when the engine is off I can induce the rattle. Once again it sounds like something has broken loose, yet the engines performance seems unaffected.

Thanks guys you have got me thinking. I’m really into this. I just went back out to the car and with the engine off, directly in front of the grill, I grabbed the Mass Air Flow Assy and shook it from side to side with very little effort and got a very loud rattle. Something must be broken I’m convinced.

I case you’ve not been happy with the A/C cooling ability, I’m going to make a separate post telling how I greatly improved the performance of the A/C unit: Scion xA: A/C not cold enough fix

I found the cause of the rattle after confronting the dealer to have a mechanic open the air mass flow plenum. It was what I would call, the air resonance intake tube, that had fallen out of its retaining bracket (I think likely broken at the factory or by their service dept. as it immediately falls out and will not latch in place.) At times it rattled quite loudly as it hit the side of the air mass flow chamber. It has been going on for about two years, but I was always told it was normal. I really do get tired of fixing damage cause by dealers to my car. Stripped threads in large plastic molded parts such as dashes when they remove radios or install accessories. That is why I install accessories myself.

Scion sprouted from Toyota, but the cars are NOT Toyota built!

Who told you that??

Scions ARE built by Toyota. In fact they share many of the same engine/parts as their Toyota Siblings.