Looking for some help. I have a 97 4Runner with a 2.7/auto. The truck runs great gets 22mpg and has no leaks or burns any oil. It has 130k - The only issue is at idle the motor makes a "churning" sound kind of a light growling sound. I thought it was the idler pully (I changed both) but the sound did not change. I then removed all belts to see if it was any of the attachments but I still had the sound. I then used a listening device and believe I have traced the noise to the front of the motor in the head area. I have had 2 master Toyota techs listen to the truck and both had no idea. I have only had this 4Runner since 115k - the noise was present when purchased and has not gotten any worse. Please help!

 

Sounds like the timing chain. It would be wise of you to change the chain at 130k. The chain should be showing its age, and if it breaks it can cause major damage. It is preventative maintenance to change it now. If you want a little more grunt out of the engine, you could put in some adjustable cam gears at the same time and advance them to gain more low end power.

 

Thanks for the info. Is the 2.7 pron to breaking the timing chain?

 

ive never heard of one breaking yet, pull the valve cover and take a look, turn the engine clock wise (looking at from the front), and see if there is any slack on the passenger side, if there is then you need a chain kit, if not then the chain is probably not your problem, there is a transfer gear on each cam that could make some noise, how loud is the noise?

 

It can only hear it at idle, once you give it gas the noise goes away. At least I think it goes away, once the revs and fan wind noise kick in I can't hear the growing.

 

FYI, the 3rz 2.7L motor is non-interfearance, so if the chain breaks it will not cause any damage to the motor.

 

would it be wise to change it or drive it till it breaks?

 

Change it. If it breaks you will be left stranded and paying for a tow back home.

 

I picked this 4Runner up off my sister-in-law (the original owner) she lost the owners manual - Did Toyota recommend the chain being replaced at a certain interval? I am still going to change it.... I just wanted to know.

 

sounds a lot like what I have been experiencing

Is it consistent? Does it happen everytime you start your truck? Mine is intermitent.

 

Are you sure about that? I always thought the 3rz was an interference engine.

 

if it were a 22RE, i would suspect that you aren't getting adequate oil pressure to the t-chain tensioner at idle or the t-chain tensioner is sticking and the normal oil pressure at idle is not enough to breaking it free. (then, when you rev it and the oil pressure is higher, it is enough to break it free.)

i have no idea if the 2.7 setup is the same way or not, but prolly something similar. might want to check your tensioner.

 

I doubt it...are you sure that Toyota didn't mean "Timing Belt"?

 

The 2.7 is a chain. The noise is everytime the motor is idling. It does get loader under load at idle (AC) but is not the AC system. Anyone else have this issue.