Stretched Timing Chains? 1GR-FE 4.0L

Introducing my 2008 TRD Sport 4x4 DCSB with 249,500mi. The truck was my grandfathers before he passed away and I came into possession of it around 190,000mi a few years ago.

Several months ago when outside temps were in the 10s, the truck started showing a pending P0016 on my cheap Autel scanner. One day on my way home from work the code fully popped the MIL a few minutes after starting the truck cold. After clearing it hasn't returned since.

The truck doesn't idle very smoothly and has developed a loud, resonant, deep rattle like noise from the engine when going up steep inclines at low RPMs (1000-1500) or briefly when taking a sharp turn. It is almost reminiscent of a power steering groan. It makes the noise in drive, neutral, rolling backward on an incline, with the wheel straight or turned, but only under specific conditions. RPM has to be kept around 1000-1500 on an incline, sometimes no incline, sometimes just turning.

All this lead me to remove my valve covers (again) to verify timing and this is what I found. To me it looks like the chain has stretched and caused timing at all marks to become slightly retarded. I also noticed that the secondary chain between intake and exhaust cams was decently loose on the sprockets before turning the motor over 720 degrees back to 0 again. Slack disappeared after rotating the motor over again. Not sure if this is normal.

I would like some opinions on how this looks before I go ahead spend the time and money on new chains, sprockets, tensioners, and guides.


Appreciate any insight.

 

Dont you need to keep rotating until the 2x orange links line up with the marks? Ive never timed one so maybe someone else will chime in @TnShooter

Any other codes? P0016 is known for timing chain but I did have an issue with one of my oil control valves dying. Presented codes 0011, 0012, and 0016, idled & ran terribly etc.

Those pics make it look like it was well cared for / clean on the inside aka regular oil changes

 

The paint mark on the chain are more for installation. You’d be tuning the engine for a long time to get paint marks to line back up. The most you should have to turn it would be 1 extra turn at the crank. TDC happens 2x. Once on compression, and once on exhaust. That’s the reason you “might” have to rotate the crank one extra time.

To me, the drivers side looks to be a half tooth off.
Compare OPs picture to this one.

 

Right, painted links on the chain itself I believe are just for installation purposes, so you can line up the correct teeth on the sprocket(s). As you can see in the original post I have marked the correct tooth on the sprocket as well as the timing mark on the cam bearing caps with yellow paint pen.

@TnShooter would you say timing is only off on Bank II (Drivers Side)? Tensioner on the main chain is on Bank I, so, I would think if the chain is stretching, Bank I is where I'd see it first. Please correct me if this is wrong.

Appreciate the feedback.

 

Can you post a picture of the timing mark on the crank sprocket as well just to confirm it is lined up as well? Also, pop the tensioner inspection cover off and take a picture of the tensioner. That will help determine if the chain is stretched or not.

 

Truck is currently back together sitting in the driveway and I didn't get the chance to snap a pic of the pulley. After checking the first time with the crank at 0 degrees, I spun the motor over twice back to 0 and results were the same, except the Bank I secondary chain no longer had any slack.

If I pull it all apart again ill make sure to grab pics of the crank pulley lined up aswell.

Below is an image of my tensioner from what I could see with valve covers removed, it has definitely ratcheted out at least twice.

 

P0016 is for cam sensor 1.
The crank pulls the slack down and out from bank 2 cam to the crank.
It makes sense that bank 1 would be retard with a a stretched chain. And your is retarded.

@Bishop84 has a lot more experience with the 1GR than I do.
I bet he knows exactly what the first signs and symptoms are.

 

My understanding is Stretched chains are often due to an ovetheated chain. I.e. a broken guide or other frivtion. You could check stretch by seeing how many degrees slop you have when you switch direction. A quick indicator is the colored timing marks fade when heated. Yours look crisp.

 

I have a very similar situation on my 08, but no codes. Discovered while preparing to pull the cams for leaking valve seals. Cylinder #2 has the leak, I assume.
Did this go anywhere or do others have input?

https://www.tacomaworld.com/threads/remedy-leaking-valve-guide-seals.848730/#post-30367548