i have a 2005 base TL. i have noticed that since i bought the car there has been a rattle in the engine that has increased in sound, especially when the car is idle. i think it is because i forgot to use premium gas a couple of times when i first got the car. has anyone had this problem? is there a way to get rid of the rattle?

 

That's a very generic description and it's impossible to tell what it is based on your description. I have a few comments:

1) It could be the valve train chattering. A common maintenance item on our cars is a valve lash adjustment, especially if you go too long before changing your oil. Check the oil level first, make sure it's good.

2) Worn engine mounts - another common item - cause excessive vibration. Try to determine if the sound is coming from the engine itself (internal) or if it's just something else in the engine bay that's vibrating.

3) Is the noise audible through the entire RPM range? Or does it disappear after a certain threshold?

 

the car was recently serviced so the oil is good. the sound is a rattle coming from the front end of the car not out of the exhaust. the sound is loudest and most noticeable when idle and at low rpms

 

Hmm. Obviously I can only help in a limited way lol. I would determine which of the following categories it falls in.

1) Body/Non-Engine: Something that is not the engine or an engine component is rattling. The easiest way to find this is to put on a glove and grab/touch stuff until the noise changes/disappears. Boom, you have found your rattle. It could be caused by a loose bolt, or a worn engine mount.

2)Engine external/Accessory drive item. Remove the Accessory drive belt and start the engine. Is the noise gone? If yes, then the noise is coming from one of the belt driven parts or the tensioner. If no, then the noise is engine internal.

3) Engine internal. If you've narrowed it down to this, take a video and see what people on the site have to say. After I adjusted my valves, my engine became whisper quiet compared to what it was before. If you have an '05, it might be time for that. How many miles on your car?

 

i just hit 100,000. ill go out and see if i can get a better understanding of where its coming from right now and then let you know

 

the sound is definitely coming from the left side of the engine where the belt is and gets faster when i rev the engine and either goes away or is drowned out when i hit really high rpms

 

Excellent deduction. Next, take off the accessory drive belt and start the engine. If the sound is still there, then the problem is internal to the engine, likely the timing belt. If the sound disappears, then it's coming from one of the accessory items.

IF the noise is gone, check all the pulleys to see if any are loose and check the condition of the belt. If you can, measure the torque of the auto-tensioner to see if that's what needs to be replaced. If you still can't figure it out, put the belt back on and try listening very closely to see which part is making the noise. I've done this before and I was probably staring in the engine bay for over an hour before I was confident in what the problem was.

IF the noise is still there, then it's probably something related to your timing belt, which is not unusual since your 105k service is coming up. This service replaces the timing belt and tensioner (among other things). I would say that if the noise is still there, get your 105k service done first.

Edit: don't run the engine for too long with the accessory belt off, your battery will drain. You should be able to tell within a matter of seconds whether or not the noise is gone.

 

okay ill do that

 

i couldnt get the belt off without taking apart the engine. still do it?

 

What the hell? release the pressure on the tensioner and take the belt off.

 

taking apart the engine was an exaggeration. i just couldnt get the belt loose because it so tight

 

That's because you have to relieve the pressure off the tensioner, you can yank and tug on the belt it all you want, its not coming off unless you release the tension. Use a breaker bar or slip a pipe over your ratchet for more leverage.

 

alright i will tomoro. it was a really half ass effort because it was getting dark and i didnt have time but i was just checking it out.

 

You know you were struggling. lol


I kid, I kid.

My vote: The Bearing on the belt tensioner. These tend to fail as well. If it does end up being that, save yourself some time and spend the extra cash on the entire assembly, instead of fiddling with the pulley alone.

 

check A/C compressor and alt. A/C comressor cam make that type of noise...