i have a 2000 blazer with 178,000 and when you drive it the engine has a rattle. Its not really like a lifter ticking but a loose rattle. im not sure what it is any help would be greatly appreciated.

 

Any more details about the problem? Does engine RPM matter? Ground speed? How about the type of rattle? Does it sound like a piece of sheet metal vibrating or more solid? Where do you hear the noise coming from?

 

It does at any rpm and it is kind of hard to describe but not like sheet metal but like more like a quiet spray can rattle. I know that's strange but it's the only way I can explain it. Maybe a timing chain but idk. It definitely in the engine compartment but you can hear it really good while your inside the vehicle. It also speeds up or slows down with throttle

 

Crawl under the truck and smack the catalytic converter with a chunk of wood or a rubber mallet. Does it make a similar noise? If so, the catalytic converter is on the way out.

 

Thanks a lot for the idea. I got under there and hit the cat and I heard a vibration but it wasn't from the cat. So after about 10 mins of tapping I found out it is a spring or something in the O2 sensor that is loose. It makes the same noise. Ill take it out and look at it tomorrow

 

Check your PCV valve I know those rattle but usually stop as you accelerate... Also there is a tsb for the timing chain or something with the timing gear/tensioner... Also make sure nothing is interfering with the axles, fan, belt etc...

O nvm just saw u foind it was the o2 sensor.

 

Yew but thanks anyway. It was definitely not what I was thinking it was.

 

Well I took the O2 sensor out today but that's not the rattling. There is something metal inside my exhaust under my O2 sensor. It's just a flat section of exhaust so I guess whatever it is is just sitting loose right inside the pipe. I just hope it is not an internal engine part

 

Try squeezing it with a glove on or something or with the car cold and see if that helps....

 

Ok I will