2007 Toyota Highlander 2.4L loud knocking during cranking.

Hello everyone, new to the page and I'm hoping maybe someone can help. First, some back story. The vehicle was taken to someone else for a tapping noise during idle. The shop replaced the serpentine belt and the timing belt along with the VVT actuator. The vehicle left that shop with the same tapping noise I have now. But before it got to me, the owner took it to a dealer in an attempt to diagnose the issue. Dealer said it was internal and they'd need a full day to diagnose. Being that it was $1300 just for that, the customer decided to let it sit for a bit until he could decide what to do. In conversation (he's a family friend) he found out I sometimes work on cars and so I agreed to at least take a look.

When it arrived it had a P0016 code for crank/camshaft correlation. Before taking anything apart I started by testing crank/camshaft sensors. They seemed ok. Then used the scanner to try and activate the VVT solenoid. There was no change in idle when activated/ deactivated at idle. So I removed and tested the solenoid and it tested good. So then I removed valve cover and found that the intake camshaft was off timing by one tooth. In the process of repaint that I removed the oil pan and checked the oil pump strainer. Found an insane amount of trash in it which I cleaned out of course. After I reassembled everything, the timing code was gone since I corrected the cam timing. But the loud tapping during crank is still there. Well, sometimes. I turned it on/off about 10 times today and it only did it half the time. It has gotten better but in needs to be completely gone. I believe cleaning out the oil pump pick up helped since there is more oil going through the engine and the actuator is oil driven. The sound is coming from the top of the engine but I cannot pin point it. I've heard that if the actuator is installed in the locked(maybe unlocked) position for the first time, that it could damage the unit. I'm leaning towards a bad vvt actuator since the engine idle does not change when the vvt actuator test is commanded on the scanner. Also, when the engine is revved close to 3k it starts to rattle again.

Sorry for the long post but it's a lot to describe.

Update 8/29/22.
Decided to remove valve cover and spark plugs so that i could turn over engine using the starter and listen/ look for any noise/ strange movements. During this test, nothing abnormal was found. So I took apart the VVT actuator and it all looked normal. I then decided to crank the engine over with spark plugs installed and the knock returned. So it seems that the knock is there only when there is pressure in the cylinders. I'll have to take the oil pan off and see if there is anything lose in the crank or underside of pistons.

Sorry I'm late to the party. :silly: But it sounds like you've got a pretty good handle on this one.

I then decided to crank the engine over with spark plugs installed and the knock returned. So it seems that the knock is there only when there is pressure in the cylinders.

For whatever it's worth, I think you've pretty well got this narrowed down to a lower end issue. Piston, wrist pin, connecting rod bearing, like that. But if you feel like taking the time, you could experiment and remove one spark plug at a time. :huh: When you remove a plug and the cranking noise goes away, that's the cylinder with the issue.

I'll have to take the oil pan off and see if there is anything lose in the crank or underside of pistons.

It's been awhile since I had the oil pan off of a 2AZ, but I don't think there's much to see with just the lower pan removed. Pretty sure the balance shaft assembly is in the way. However, if you find bearing material or the like in the bottom of the lower pan, then you have your answer.

You are correct. Not a whole lot to see under there. I replaced the oil pan gasket when doing the timing chain correction and the balance shaft cover is blocking the view of it all. I was thinking of removing that cover as well in hopes of having a confirmed cause for the issue. Owner of the vehicle said I don't have to look into it further if I don't want to but I'm very curious to find out what it is.