Good afternoon. I have a 2015 4 runner that I just replaced valve seals. I did this with the engine in the vehicle and without removing the timing chain cover. I have the cams back in and am having trouble getting the time chain on correctly. I can get all of the slack out on bank 2 up to the intake phaser and have that cam lined up with the timing marks. On bank 1, I need to rotate the cam clockwise to then install the chain to get it to rotate back to the right position to have the cam time correctly. The problem is that when I rotate this cam, the exhaust phaser also rotate and then the flat side of that phaser is not longer in the right position to allow space to get the chain on the intake phaser.

I'm sure there is a simple solution, but this is a puzzle to me right now. I'm not ever sure I'm making sense explaining this, but hopefully someone else has done this and understands what I'm talking about.

If anyone has any suggestion, I would great appreciate it.

Thanks,
Keith

My guess is that you are battling the chain tensioner which is extended and trying to get things back together correctly without collapsing the chain tensioner is going to be a battle. You would have to remove the timing cover to collapse and pin the tensioner.

I have the chain tensioner off, as there is an access panel on the timing chain cover.

Thanks,
Keith

I managed to get the chain on after finding the details in the service manual. Here was my situation and solution:

I was replacing the valve seals without removing the timing chain cover. After removing the timing chain from the VVT, I secured it with a zip tie to keep it from falling into the engine. At some point, the zip tie must have broken, as I found the timing chain laying in the engine. Not knowing if the chain had dropped off the crank gear, I was uncertain how to time the motor without removing the timing chain cover.

I didn't want to remove the timing chain cover, as this would allow more opportunities for me to mess something up, require additional parts/gaskets, and would take a lot more time. Instead, I used a borescope to look at the crank gear to see if the yellow link was on the right tooth. Unfortunately I couldn't see the dot on the correct tooth, as the space between the sprocket and timing chain cover was too tight. I could see the yellow link and I could also see the dot on the crank sensor plate and the line on the block to align TDC. So I aligned TDC from that plate and mark and confirmed #1 cylinder was at TDC on the exhaust stoke.

Once this was aligned, I noticed the yellow link was approximately two links away from where it should be on the sprocket base one photos and videos I found online. So I assumed the chain had slipped of the crankshaft gear when it fell and I needed to compensate for this with the orange links that are supposed to line up with the timing marks on the VVTs by placing them in place two links away from the timing marks.

My issue with getting the chain on the VVTs was resolved by first placing the chain on the bank 2 VVT while keeping it off the bank 1 VVT gears. Then I rotated the crankshaft to rotate the timing chain to the position needed to get the chain on the bank 1 VVT. After it was on both VVTs, I rotated the crankshaft back to the TDC mark. This left a lot of slack between the VVTs, which was correct. I then rotated the camshafts in bank 1 counter clockwise to align the timing marks and remove the slack. This put the slack under bank 1 where the timing chain tensioniser is located, which is correct. I then installed the tensioniser. Lastly, I rotated the crankshaft a couple full rotations to make sure everything was turning smoothly with no binding.

I was still a little nervous that I didn't time this correctly, since I didn't have the cover off to do it the right way. But after many, many hours of research and staring at the engine, I felt confident it would at least turn over without blowing up. I just wasn't confident it was timed correctly, as I feared I may be off a tooth or two.

When I started it, it fired up almost instantly with NO CODES. So far I've only driven about 5 miles, but it seems to be right.

I hope this helps someone else that ran into my issue, as I couldn't find any information online for what to do if you drop the timing chain when making this repair.

Have a great day,
Keith