Heres the video. Don't know if this is a normal amount of "knocking" or what.. car has 127k miles on it. Video was recorded from passenger-side wheel well.

http://www.youtube.com/watch?v=q6OFN...ature=youtu.be

 

No input?

 

Pull the serpentine belt. Is the noise still there? If so, I'd guess your TB tensioner is shot.

Has the TB been replaced yet?

 

When my timing belt tensioner was going, it would get louder and knock faster when accelerating. There was a lot of give in the timing belt, so I would get it checked right away. I got lucky and it didn't affect the timing. I was only at 100k km or 60k miles.

 

I can check that. Was just done at 110k though.

 

Il check to see how much play is in the timing belt too.

 

I've checked everything at this point. The sound was moving the exact same speed as the rocker arms when I removed the oil cap to see. So I took both valve covers off and checked everything but could not find anything so this leads me to assume it is bad news.

 

Did you remove the drive belt?

 

Yes I did.

 

could be a bad TB tensioner.... dunno

 

^^^ thats what mine was. my car never sounded as good after i fixed it. your noise sounds similar

 

I hate to say it but that doesn't sound good. I can hear the hum of the timing belt tensioner but the knock is the main noise. It's definitely I'm time with the cams/power stroke, meaning half crank speed.

To determine what it is, I have a few questions.

Does it get louder with rpm or with load? Try powerbraking it to the point you put a load on the engine. Put it in park and bring it up to the same rpm. Is it louder in drive or is it the same?

Is the noise better or worse when cold?

Are your plugs tight? It's probably not a plug due to the location but it's easy to eliminate.

It sounds like a hurt piston to me but it's hard to tell without being there.

You can see which cylinder it's coming from by removing one coil plug at a time and seeing if the noise stops or lessens on one particular cylinder. Don't remove the coil plugs for more than a few seconds be use the injectors will still be firing and you don't want to dump raw fuel.

If the noise stops on one particular cylinder it's not a valvetrain issue, it's a plug, piston, rod, or severely blown headgasket. My bet is on a piston but I hope I'm wrong. If the noise does not change by shutting down a cylinder at a time, it's in the valvetrain or it's external.

 

Thanks for the input. I can't really try engine braking it because its manual. On a cold start, I can't hear anything. It gets louder as the vehicle warms up. It does not get louder with rpm just more frequent as the engine speed increases.

Tomorrow I will try what you mentioned about the coils. Just unplug the electrical connector from each, one at a time for a few seconds?

 

Are you sure the noise gets louder as the engine warms up, and not just more noticeable since the engine gets quieter?

That does not sound great.

 

I am sure. There is no knocking when cold. Very predominant when warm.

 

I still wonder if it's the TB tensioner? But also wanted to ask if you've checked the spark plugs to see if any were loose?

At any rate, I'd say you need to take fairly immediate action to resolve this. We all agree on one thing: it doesn't sound good !!

 

Yeah hopefully I come to a consensus today. I haven't been driving it since I have another car. The TL has just been in my garage since I started hearing the noise.

As for the TB tensioner.. the knock is going the exact same speed as the engine valve train speed. That would mean it can't be a tensioner I assume.. right?

 

I'm at a loss. Pulled each coil one by one and the sound never changed at all. When in neutral brought up above idle the noise seems to get a tad quieter.

 

Took a couple more videos that you get to hear it a little better.



This is with a rev.
http://www.youtube.com/watch?v=JVYTG...ature=youtu.be

 

The plugs are one of the only things left to check.

 

Checked the plugs. Cylinder 4 was the only one "loose" and it was barely loose. All the other ones were good. So then I cold started it again and like I said before it only makes the sound when warm. Well this time after a few minutes i kind of heard the sound but barely at all. Let the vehicle sit and run for 15 minutes and it still wasn't making any sound. Can a spark plug 1/4 turn loose really be the problem? I find it weird.

 

Hmmm, that would surprise me at only 1/4 turn. And usually it's plug #5 that comes loose. But on the other hand, the sound was coming from the #4 area (or at least that side/area of the engine).. Did you happen to pull the plug and examine it for any thread deformation?

Let it run for a few days and if the sound doesn't return, maybe that was it...

 

When you figure there are pressures upwards of 1,000psi, 1/4 turn is more than enough to make a noise, the gasket is unseated and the threads are not supposed to seal combustion pressures. The timing of the noise was perfect too. I would guess the aluminum threads expand more than the steel spark plug and that might be why it's only there when hot.

 

Well to verify my concern, I loosened the spark plug 1/4 turn and sure enough the sound came back. Went to retighten it, and the sound is still there now....... with it tight. Is it because the engine was warm at this point now when I went to retighten it? Gonna wait till morning when everything is completely cold, and check the spark plug again and make sure its tight..

 

Just seems weird that the sound is still there now when the plug is tight. Can it really be because I tightened it with the engine warm? Just doesn't seem like enough to cause it to still make the sound when tight.

 

What torque spec are you using? Or is this by "feel"?

 

By feel. I've changed spark plugs many many times on many different vehicles including this one.

 

Yeah, well I would avoid torqueing a plug into a hot head. I'd let it cool and check it again.

As far as torque and feel, the SM calls for using anti-seize and 13 ft-lbs. With no A-S, then I'd go with the NGK recommendation of 18-21 ft-lbs.

 

^^^ and again, I'd pull that plug and check the threads for any deformation or damage.

 

I would never torque any bolt in hot aluminum. It's a good way to screw things up such as stripping the heads. There are a couple things that might have happened. More tomorrow.

 

Well, I'm confused. Let it sit overnight, and while I was at work today. Plenty long. It's 5 degrees outside. On my way home from work I stopped and picked up a new spark plug. Pulled the old one out and put the new one in. Started it. let it run. drove it. etc. Everything seemed fixed. Went to the gym, and when I came out and started my car the sound was back. So I really have no idea where to go from here at this point..

Plug I replaced:

 

Could it be an issue with the head? slowly pushing the spark plug back out or something.

 

I suppose it's possible, but I kind of doubt it. Is the new plug loose now? If it is loose, then you may have thread damage in the head...

 

I checked the plug this morning. Plug wasn't loose at all. I still pulled it out to check it and put it back in (When cold). Then I went to start it and the sound was there immediately (see video) and then went away for 5 minutes, then reappeared. But it is barely there, You can only hear it with the hood open and listening up close for it. (This is with the car now at operating temp and running for about 15 minutes.)

In the video the sound is going faster because the rpms are higher.


http://www.youtube.com/watch?v=G6Qva...ature=youtu.be

 

To me, the fact that the sound is there immediately (cold), then disappears for a time, then reappears would seem to rule out a valve train or internal issue... Does that make sense?

I know the sound tempo doesn't seem to match up with a faulty TB tensioner, but were you able to get a good look to see if the tensioner was leaking or loose?