E320Star

I noticed in cold wheater and specially in the morning. When I start my car it runs fine and the engine sound is smooth. But after 4 -5 minutes running, I cxan hear a low ticking sound that goe saway when I press the gas pedal. When the car is warm and I drive away no more ticking sound. I always use syntheic oil and it just replaced it. I replace the oil every 5k miles with synthatic. any suggestions why this ticking sound. Thank you

figure1a

Might be the sounds of a deteriorating catalytic converter (I know the sound as I've had all 4 replaced on my 2000--a well know problem). When your cat goes, at first you usually hear a ticking sound at idle and low RPM (when the engine is most wobbily and it is shaking everything connected to it including the exhaust system). The ticking sound is small parts of the cat breaking apart inside and rattling. As it gets worse you will hear it at more times. I know the ticking sound right now probably sounds like it has to be on a moving part of the engine but it can fool you. When your cat is really deteriorated the ticking turns to a rattle and soon sounds like you've got rocks in the engine. The time from tick to rocks can take up to 10,000 miles. So if you're under warranty now and may be out soon, you should probably have the dealer look at it (and, by the way, emissions warranty is usually longer than the standard warranty--emissions warranty is 7/70 here in California). Of course I could be wrong and you may just have a piece of tape stuck to a belt but I suspect it's your cat.

E320Star

It is the same here too in KC 7/70 on the CAT. I have 46k miles on the car only. I doubt it is the CAT. When the cat starts having issues, usually with higher mileage one's and it will sound at all times hot or not. This ticking starts only after 5 minutes of running the car in the morning only. and it goes away completely all day long until next day morning start.