[Kooter]

I'm wondering if anyone has experienced [from time-to-time] a brief, loud rattle noise for approximately 1 second at cold start-up. This brief (approximately 1 second) loud rattle noise (sounds like jerking a chain quickly out of a plastic milk jug) has happened with my 2004 V6 3.0L engine from time-to-time for about a year now. The noise is definitely not associated with typical cold start valve ticking, etc. that many people have. It is definitely coming from the intake-side of the VVT system.

Toyota has identified certain Lexus models built between 2006-2011 with this VVT noise problem, and issued a voluntary recall. However, Toyota apparently never had many customer complaints or problems to address any Toyota model vehicles with this same type VVT noise problem that I'm aware of. Plus, my car is now 11 years old with 128k miles...so it did not developed the problem until well after the original warranty.

The reason why I am offering this information is to help people (that may have this brief, loud rattle noise for approximately 1 second at cold start-up that may only happen randomly) that cannot figure out why or where the noise is coming from...

The following information describes the problem:

Bolts used to secure the variable valve timing control device can become loose, causing the vehicle to stop while being driven. Early warning for this condition can be identified as a brief rattle noise for approximately 1 second upon a cold start-up.

Description of Problem:
The subject vehicles are equipped with a Variable-Valve Timing (VVT) system which controls the camshafts to provide optimal valve timing under certain driving conditions. The bolts used to secure the housing and sprocket of the intake-side VVT gear assembly could become loose due to abnormal impacts generated within the gear assembly immediately after a cold start-up.

If this occurs, the VVT gear will not control the intake valves correctly. In certain cases, the VVT gear housing and sprocket could separate and result in the engine stopping while the vehicle is being driven, increasing the risk of a crash.

Toyota theorized that the condition could be related to an engine noise issue at start-up being investigated on certain engines. The VVT internal component could rattle when the lock-pin, which latches to the VVT housing and secures the internal components to maintain the camshaft in the most delayed position, unlatches at cold-start. Toyota conducted reproduction testing and was able to duplicate noise but was unable to duplicate the loose bolts condition.

Through reproduction testing, Toyota confirmed that, with the lock-pin disengaged during a cold engine start, the impact force between the VVT internal component and the housing could become larger if engine oil, which is pumped into the VVT unit to control the position of the camshaft, drains back into the oil pan while parked. In addition, Toyota theorized that the impact force varies in specific engine types due to cam profile and intake valve spring load. Toyota continued its investigation and testing to clarify the relationship between the impact force exerted inside the VVT housing at cold-start and bolt loosening.

I hope this information may be helpful...

 

[hardtopte72]

This issue has recently come up in other areas of the forum and after watching some videos it appears that this issue affects Toyota engines even from the 90's when the gears wear out.

It also isn't limited to Toyota but also affects Nissan VCT and Honda i-VTEC camshaft pulleys when the locking pin fails.

This just appears to be a problem associated with the design of the cam phasing gear wearing out.

 

[Kooter]

Thanks for that information. It sure makes a loud and rapid rattle when that pin becomes unlatched at start-up. When it does happen, it's always after sitting overnight when the oil has drained out of the VVT system.

One day I might get it fixed. Do you have any idea how much a Toyota dealer would charge?

 

[hardtopte72]

Thanks for that information. It sure makes a loud and rapid rattle when that pin becomes unlatched at start-up. When it does happen, it's always after sitting overnight when the oil has drained out of the VVT system.

One day I might get it fixed. Do you have any idea how much a Toyota dealer would charge?

A crap load probably. On the 1MZFE the VVT-i gear is at the rear of the camshaft nearest the airbox. Removing the camshaft would be necessary which would require a timing belt job and valve cover removal on both banks at a minimum (to do both VVT-i intake pulleys).

I would either do it myself, or leave it alone.

Here are some videos of VCT rattle.

20V 4AGE

Nissan SR20

Before new gear:

After new gear:

 

[kitacamry]

This issue has recently come up in other areas of the forum and after watching some videos it appears that this issue affects Toyota engines even from the 90's when the gears wear out.

It also isn't limited to Toyota but also affects Nissan VCT and Honda i-VTEC camshaft pulleys when the locking pin fails.

This just appears to be a problem associated with the design of the cam phasing gear wearing out.

Yes...I think of you guys each morning when my neighbor's Accord screeches for a split sec. at start up, and wonder when it'll be my turn....

 

[Kooter]

The before and after sound in the Nissan above video doesn't sound anything like what I'm describing (or Toyota wrote about in the article I posted above). The rattle noise period is a quick 1 second time period that sounds much like jerking a 2 foot long chain out of an empty plastic milk jug. The 'before' Nissan video has a continuous clatter...unlike what Toyota or I am describing. (Note: The noise goes away on the Toyota as soon as the locking pin latches in the controller, which as Toyota states is only approximately 1 second. Maybe the Nissan's VVT locking pin never latches, which causes its noise to be continuous - dunno.)

I believe with my car the sound is coming from the front (nearest the front bumper) and on the passenger side. If I'm not mistaken that is where the VVT intake-side controller (actuator) is located on the intake cam. I would only have the one VVT controller replaced that is making the random noise.

This is the controller parts [similar for example purposes] that would need to be replaced on the one intake cam.

http://www.youtube.com/watch?feature=player_detailpage&v=YjIKUrre4FQ

The above linked video shows VVT controller, how it works...and the problem it can have when the pin unlatches at start-up.

I might ask my dealer for a repair estimate to repair/replace the VVT controller/actuator (housing, sprocket, gear assembly) on just the one intake cam that has the random problem. If anyone has an idea of what it may cost - I'd appreciate you guessing...because I really don't have a clue. My guess is somewhere in the $750-$1,500 range.

 

[Kooter]

This video describes the 1 second VVT rattle sound pretty nicely.

A lot of people may think this noise is valve train noise caused by an oil problem - such as engine oil not reaching the upper part of the engine quick enough, too heavy weight oil, etc. It is not! This noise is the result of a VVT controller pin not engaging at start-up. The noise is masked when there is oil inside the controller housing, but after the car sits overnight the housing is mostly void of oil and the noise is heard [whenever the pin does not latch].

 

[ccl088]

I've got this 1 second rattle on cold start up. The car has 21k miles and dealer maintained so It's can't be from wear already..

 

[Kooter]

I've got this 1 second rattle on cold start up. The car has 21k miles and dealer maintained so It's can't be from wear already..

In your case you are probably one of the unlucky ones that have this problem earlier than most. However, with only 21k mileage you are lucky in that you should be able to get it fixed at no charge under warranty. The problem you might likely have is getting the service department/technician to hear (duplicate) the noise if (like mine) it only happens once every 10-15 cold starts. In essence the service department could keep your car for two weeks and crank it every day and might still not hear the noise...and rarely (if ever) are they going to agree to repair something if they cannot see, feel or hear the problem.

Now, at least you have some knowledge so you can actually tell the service department what the problem is.

 

[Kooter]

Another video with the VVT rattle sound (valve cover off) that lasts approximately 1 second.

 

[ccl088]

Does it at EVERY cold start up and after being driven and then set up a couple hrs but not as bad a rattle as when 1st started over nite.

 

[Kooter]

Does it at EVERY cold start up and after being driven and then set up a couple hrs but not as bad a rattle as when 1st started over nite.

What vehicle, year, engine?

 

[ccl088]

What vehicle, year, engine?

Camry, 2011, 2.5 I4

 

[hardtopte72]

All same problem, those are just worse. The sound is caused by locking pin failing to lock the gear and the rattle until oil pressure is built up.

 

[ccl088]

All same problem, those are just worse. The sound is caused by locking pin failing to lock the gear and the rattle until oil pressure is built up.

OK sounds simple but will it cause long/short term damage like the OP implied?

 

[hardtopte72]

OK sounds simple but will it cause long/short term damage like the OP implied?

Probably not of its only on startup. If it's all the time then maybe.

 

[Kooter]

All same problem, those are just worse. The sound is caused by locking pin failing to lock the gear and the rattle until oil pressure is built up.

Exactly! I'm sure this [brief] loud rattle sound has been mistaken for poor engine lubrication.

When this noise happened with my engine the first time I originally thought my oil filter's anti-drain valve had failed and the oil filter had became void of oil, which caused an extra second or two for the oil to reach the upper part of the engine. After trying 2-3 different brands of oil filters within a few weeks' time I determined that my original belief about the oil filter losing oil overnight was wrong. And I knew the engine oil viscosity that I have always used wasn't the problem because I have always used Mobil 1 0W-30 and 0W-40 since the car was brand new, which provides excellent oil flow for cold start-ups. Other than this [randomly happening] VVT rattle noise my engine sounds and performs just like it did when new.

There is one thing I have noticed that I can do to help prevent it from happening. That is - to bump the starter one time before intentionally cranking-up the engine. When I say 'bump the starter', I literally mean for the engine crankshaft to be rotated the very least amount possible with just a split-second bump in-time of the starter. Some times (not all the time however) this is all it takes to latch or engage the locking pin in the VVT controller. Obviously, bumping the starter before intentionally cranking-up the engine is nothing more than a 'possible' Band-aid method to prevent the problem on a case-by-case basis. The real fix is to have the VVT controller replaced. And how much that will cost - I do not know. I'm sure the cost varies depending on whether the engine is an I-4 or V6, and likely in the case of a V6 engine, which bank (front or rear) needs the VVT controller replacement.

 

[rena]

Choked!! This is my sound to my 4 cylinder 2009 toyota venza. I just bought it to. It has 140,000 k on it. NOT MILES...And it does makes the 1 second sound. I did not buy it from toyota and there is no warranty. I do have a month to exchange it but i love my car. ( I had some mechanic look at it today and he said i needed to replace the timing chain!) Moron..
So from what Im hearing…I have to get this gear and have it replaced to make this sound go away? Im in canada and where on earth do i do that if thats the case.:facepalm:

 

[Kooter]

Choked!! This is my sound to my 4 cylinder 2009 toyota venza. I just bought it to. It has 140,000 k on it. NOT MILES...And it does makes the 1 second sound. I did not buy it from toyota and there is no warranty. I do have a month to exchange it but i love my car. ( I had some mechanic look at it today and he said i needed to replace the timing chain!) Moron..
So from what Im hearing…I have to get this gear and have it replaced to make this sound go away? Im in canada and where on earth do i do that if thats the case.:facepalm:

Just make sure that you recognize the difference between the sound of a VVT controller ratcheting back-and-forth within the housing for approximately 1 second due to the locking-pin not latching/engaging at start-up versus the sound of a engine's valve-train not getting oil quick enough at start-up. Also, if a timing chain has too much slack, it can make a thrashing sound too. The sounds are similar...yet different.

 

[rena]

I have no idea what the difference is… Is there a video of the different sounds? I want to get this fixed. I love my car and will do what i have to do. Im going to take it to a different mechanic next week but do I say I'm curious what is that noise?? Or do i show them this forum and tell them the direction they need to be looking. I really don't see it being a timing chain issue. I saw this so this should narrow down. I would get someone else to do that first i guess before I take it to a mechanic..
Also where is the chain on the 09 venza.