Rattling sound No one knows what it is

I posted this over in the 2nd gen forum, but hasn't gotten much of a response so I thought I'd post it in the Technical forum as well.

Anyone ever had a sound that sounds like the fan hitting the coolant hose but it's not? I've made sure that that wasn't the case but it almost sounds like the sound is coming from the crankshaft pulley. The belt vibrates and I thought that that might be the issue but but I fixed it and I don't believe that is the case either. I can't figure out what it is. It only happens at around 1k RPMS, IN Drive, and it only happens after the engine has had time to warm up. Doesn't happen when the engine is cold. Any ideas?!?

I took it to a shop here in San Diego and they pulled the belt off and it still made the noise. The tech said it sounds like the VVT spring popped loose? Ive never heard of that before, but ok... A few ideas that I have are timing chain hitting something, could be something as simple as a loose bolt, but I highly doubt it, maybe a bad harmonic balancer? I'm stumped. Took it back to the shop today and told them to pull the S/C off if they need to, but I just wanted to check here to see if anyone has ever heard this before. Hopefully I get better results posting here.

 

sounds like its the timing chain tensioner or timing chain getting worn.

 

Any idea how hard of a fix that is? I have never messed with the timing chain so I'll let the shop handle it. Hopefully if that's what it is it doesn't cost me an arm and a leg.

 

It can be done, you basically take the front part of your engine off to get to the timing chain cover, take off the timing chaing cover, replace the timing chain,pulleys and since you have it apart change the timing chain tensioners. I think there are 2.

stay away from the dealerships and find a good mechanics place. You'll save yourself some money.

 

Ok cool. Yea I took it to the dealership initially and they quoted me something STUPID after they couldn't even figure out what the issue was. Needless to say, I found a reputable mechanic to take a look.

 

Also a lot of times when then timing chain gets loose it will sound like the tensioner but in fact its the timing chain needs replaced...BUT since its tore apart may as well change the tensioners so you dont have problems down the road.

 

Since you don`t mention your mileage is the engine old enough to need a new timing chain and related parts ??

You can`t rule out heat shields and other parts that just vibrate at a certain rpm

Noises can be really hard to track down I had one that we finally tracked down to failed welds on the muffler baffles .

The owner of the truck was sure it was in the front of the engine since it only would manifest while driving and around 1500 rpm no matter the road speed .

Tracking noises down can be a real pain best of luck

 

I only have 60K miles on my engine. The noise didn't start until after I installed my supercharger.

 

So there is a really good chance that something got knocked around during that time.

I was gonna say you belt tensioner is "shaking" under the new load the supercharger has put on the engine.

Seems more plausible to me, than a timing chain would be considering your mileage.

 

Yea that's initially what I thought it was too so I took the belt tensioner off and reinstalled it but it kept happening. I took it up to a shop last Thursday and dropped it off to see if they can figure it out. Haven't heard anything back. One guy said it might be something called a VVT Spring.... but I don't really mess with the internals that much so I wasn't sure what that was.

 

http://www.toyotanation.com/forum/6...n-2005-2015/182494-new-fix-tapping-sound.html

Not timing chain; give that a try first.

I use to own a 2005 Audi S4 with the famous 4.2L V8; incredible engine but prone to failures of timing chain guides and tensioner. Well at 140k miles the timing guides finally went out; small crack and it caused the chain to loosen up but it still drove fine. The chain noise would only come on during startup but when the engine is running noise went away. Pulled motor out and apart and fixed it for spanking 3000+ dollars just in parts; new timing guides (ouch, with me doing all the work at home.

Never even heard of these 4.0 v6's timing guides going bad and definitely not at your mileage.