That sounds like a pretty good description of whata variable valve timing unit failure could sound like, although I have yet tohear a bad one myself. I don't know if the factory rebuilt engines have new V V T units fitted: because of the cost and the infrequency of failure, I doubt it. So the V V T's may have alot more than 40K on them.

The secondary tensioners are the only thing you can change without removing the timing cover, and it's hard to imagine that they are causing constant chain noise until the V V T's "clack" when they are activated.

If I was checking out the car, I'd try to determine with a stethoscope whichbank the noise was coming from. Then I would disconnect the appropriateV V T solenoid, and see if the noise eventually dissipates...or if it definitely requires the V V T activation.

You can rotate the V V T units by hand to check the internal return spring (which is pretty heavy on the early type units), but I don't think you can do so with the chains still connected. Maybe a stuck unit would be evident if you were to check the alignment of all four camshaft flatswith the flywheel locked at timing position.

The left bank intake cam is the one which talks to the cam position sensor, so if the left V V T was not retarding I would think you would have a DTC code. AJ26 engines like yours do not monitor right bank cam position: if the noise is coming from the passenger's side of the engine and you can confirm that it is constant until the V V T activates, I think that would be the proof ofa bad unit.

It's not that big a deal to upgrade the secondary tensioners first, in hopes of striking gold. Changing a V V T means pulling the front cover off, inspecting the guide rails and tensioner blades, and upgrading the primary and secondary tensioners while everything is apart. Sounds like you might have to go deep, but the cause will be easiest to determine while everything is still assembled.

Please post any additional findings, I'd love to learn more. My opinion is that V V T's get blamed for alot of problems (and replaced at great expense) without good cause. I'm sure they can fail, I'd just like to be sure of the diagnosis.

I don't have experience using synthetic oil, but your use of the proper viscosity makes it unlikely that this has anything to do with the issue. Hope this helps you on the right path.

 

I was under the impression that the dealer-supplied engines were all factory rebuilt units, not new. Perhaps one of our current dealership associates can answer this question with certainty. The V V T's are like $400.00 each new, so I doubt the factory put two new ones in every engine they rebuilt. Sleeve the block, new rings at least, new chains and tensioners for sure, but not V V T's.

You won't hurt anything by running the engine witha V V T solenoid disconnected, at worst you will flag a check engine code. Get a stethoscope and spend some time trying to isolate the noise.

 

We can get two engines. New and rebuilt. They do come with new VVT units if it is a new engine. I have also been told that the rebuilds have new units. They reuse cams and cranks etc.
Sounds lime you may have an oil feed problem. Takes the time to get oil up to vvt unit. AJ26 is on or off vvt. Not like AJ27 with linear vvt.
As JTO states, disconnect them one at a time and see if noise disapates.

 

FJT,

Thanks for filling in my blanks!

 

sometimes the 4 seals.. there like cork material.. they sometimes..allow oil to drain down.. cant remember what kind of noise they make.. but your description sounds a bit familiar

 

The latest style of secondary tensioners have aluminum bodies, steel plungers, and plastic slippers on each end. The slippers are moulded to wrap around the ends of the plungers to make them less likely to separate.

I think jag_genius is referring to the bush carrier seals: on the AJ26 there is one each side, and if worn you lose oil pressure to the V V T's. Still means pulling the front cover.

 

2 on each side..