Rattle noise at idle

Hey guys,

Reaching out with an issue. My 2008 Tacoma is having a strange vibration at idle. Only happens on cold days and from a cold startup. The rattle is very sporadic, goes away with a rev. I took some video to try and capture the noise but can’t get it to upload! If anyone knows, or has an idea where to start I’d appreciate the help!

 

Most likely either the exhaust heat shield or the cat core itself.

If the former then look at all the plates and tap on them when the exhaust is cool and see if you find anything lose corroded or worn.

If the latter, not much can be done other than a rather expensive cat replacement.

 

i actually hear it coming from the dash, or below the dash. Kind of coming from the general direction of the motor.

 

its not really a metal rattle, it almost sounds like knocking. The truck drives just fine, read another thread stating maybe a pulley or pump going out

 

and also, when the truck is warmed up the sound goes away completely. Haven’t heard the sound all summer, only happens on cold mornings it seems like.

 

Hmmm. Happens on cold days, cold starts and goes away when reved or warmed up. I would like to hear some audio but my mind instantly went to timing chain/tensioner slap. If you have a ton of miles and it really bugs you you can always remove the inspection plate located on the front RH of the engine and see if the plunger on the tensioner is ratcheted way out, or filthy, or both.

I also like @Key-Rei's suggestions above^^.

 

I’m more inclined to believe this honestly, I’m just about to roll over 200k miles. Another friend suggested I do the timing belt, water pump, and radiator (standard maintenance at 200k)

 

I had an exhaust shield rattle when It was a little loose and I also had a similar one from my skid plate with my 2010.

 

No timing belt on a 2008 both engines use timing chains, normally you will get cam/crank correlation codes when the chains are worn out or the timing chain system has a problem although if it only rattles until it gets oil pressure (like around 5 secs after startup) it could be something in the timing system that is worn out.

Water pump wouldn't be a bad idea to change if it's never been done.

Radiator normally isn't a maintenance item either unless it's clogged, leaking, or in bad condition.

 

I think it probably is timing chain system noise. No codes present, probably the stock chain from 08 if I were to guess… and water pump for that matter.

Sometimes it doesn’t take very long for the sound to go away completely, and sometimes it just mellows out but every once in a while you can barely here it. It’s like this reverberating sound that comes and goes, louder and quieter, louder and quieter.

If you DM me, I could send you my phone # and send you the video I took

 

Post it on youtube and post the link here.

 

working on splicing two videos together, and then I’ll get it posted up.

 

Air intake at passenger fender it loses a cushion around the air intake tube where it passes through the fender

 

I addressed that when I installed my snorkel

 

Here’s the videos, the sound is quiet, so max volume.

https://youtube.com/shorts/GdTba9zhJ9Y?feature=share

https://youtube.com/shorts/WsENBmkD1JE?feature=share

 

If this were mine, I think I would still take off that inspection plate on the front RH of the engine and take a peek see of the plunger on the tensioner.

 

Intermittent problems are tricky. Since yours is when cold open the hood start it cold, jump out and start trying to find the source. A mechanic stethoscope or wood dowel might help. Before starting you could check underneath. As suggested check heat shields and cat. Look at the belt and pulleys see if anything is bouncing or oscillating weird. Is it possible it happens when you run defrost? Check the ac pump for the noise if yes.

 

That's an odd noise, can you get a sound clip from under the hood?

 

Is your truck a manual or automatic?

Auto by the brake pedal in the vids.

That isn't at all the "rattle" I had in my head. i was thinking more rain on a tin roof rattle, that sounds like a freaking MRI machine.

When you increase RPM does the frequency change at all?

 

geez that sounds like an off balance washing machine. an off the cuff guess would be the timing chain tensioner isn't doing its job when it's cold.
does it change when you go between neutral, park, or drive (all while staying still and idling)?