Hey guys, my 2007 4runner started to throw CELs last month and I kept getting an error code P0016."Camshaft Position Sensor". I took it to my friend at the local Toyota Dealer and he found that the timing chain had stretched almost half of a tooth. He said the whole thing needed to be replaced. He is working on it next week and its going to run me 1500$ . Has anyone else had this done? My 2007 sr5 just hit 201000 but I havn't had any other issues besides a water pump. Thanks for the reply.

I've heard of timing chains stretching over time. You must drive a ton to have 201K! I have not torn into the front of the 4 runner v6 but I did do the timing belt on a nissan 3.3 v6. I'd advise you to replace anything else you can while the timing chain cover is off. For instance on the 3.3 nissan motor I went ahead and replaced the cam seals a small coolant hose basically anything that I cant reach while the front of the engine is put together.

I'd just inspect everything for leaks and such while you're replacing the timing chain, if its bad fix it, simple as that.

I assume your buddy is installing a new chain and sprockets also? Its amazing what just the width of a tooth can do for timing.

Try and get some pics of the process, that would be cool to look at. Maybe replace your seals while you are in there.

You only have to worry about the seals for a timing belt because it's dry. Since it's a chain it's ALWAYS wet...at least it better be.

Timing chains do stretch..but usually don't have to worry about it for at least 250k miles. It they start stretching earlier then that..then I suspect you may not have been keeping up on your oil changes.

The V6 is an interference engine. So if the chain is stretched enough to jump a tooth or two...then it'll be the same as if a timing belt breaks...you could end up destroying your engine.

I suggest you get this fixed soon. Replace the chain and guides. Usually this comes as a kit (chains, sprockets, guides). It's a lot more involved then a timing belt since oil/gaskets are now introduced into the equation. You also have to drop the oil pan which on some vehicles requiring to raise the engine or drop the steering linkage.


Good Luck

So. He is doing it this week for 1500$ he said approx $600 for parts and $900 labor. I got a quote from the dealer and is was 3400$ OUCH!! I have been pretty regular with the oil changes and maintenance dont really know how I could have maintained the engine better.

It does happen even for engines that are maintained well. But it's rare. The only times I've ever seen a chain need replacing before 250k miles is for a neglected engine. When I removed the chain cover it was coked with sludge.

Just going to add this for future reference, should take some of the anxiety out of the issue.

Wells Vehicle Electronics
-Episode 5- Replacing a stretched timing chain on a Toyota 4.0L V6 - P0016
https://www.youtube.com/watch?v=UR50da0sDOc

There's obviously more episodes, but this is of the most interest for me today. I'm actually replacing the upper intake manifold gasket, just wanted to see how it comes apart.

...and I'll just add that I was getting this code intermittently, and noticed that my oil was a bit low (though still above the "low" mark on the dip stick). I topped it up and haven't had the code since. Maybe it's just a coincidence and it will return, but it's ok at the moment.

I get this code when the outside temp is below freezing and I do 3 cold starts in a row. When it's warm outside or I do mostly hot starts, the code goes away.

I watched all the Wells videos to understand what's going on, and I get that the code is tripped after a certain condition is met during 'drive cycles', but I cannot figure out why outside temp plays such a significant role in my case. I'm starting to suspect that the oil viscosity variation is messing with VVT system.

Not trying to jack this thread but curious on everyone's opinion on when a timing chain should be replaced if it's not kicking out codes or showing any type of issues.

Never.

I’m doing the head gaskets on my 2004 right now and my Haynes manual lists wear specs for the chain and sprockets. The chain measures fine, measured across 15 pins per the book, but the diameter of the crank sprocket and idler are both .001 - .0015” under Haynes’ spec. The exhaust cam sprockets are also a bit undersized when measured with their respective chains wrapped around them. The guides measure about .002” wear, barely any grooves at all (spec. Is .039).

Didn’t have any issues with codes or running prior to this and I’m curious what the consensus is on whether or not to replace the timing kit, or sprockets, etc. and wondering if I’m just being paranoid...but specs exist for a reason too.
I’d love to have all new Toyota parts in there but the cost is pretty rough (I just bought this in March too) and I’m not sure I trust any of the eBay stuff. I see that Cloyes makes a kit, anyone have any experience with it?

Thanks for the feedback.

The information in this threads conflicts with some of the stuff I heard in the past (but not really)… or at least maybe I didn’t get the full picture before.

I thought the timing chain was “good for the life of the motor”. I asked about needing to get this done and I was basically told it’s not needed by the dealer.

I think the entire topic came about because I needed to do a timing belt on my Acura, only had 65k miles but at 11 years old, my “selling point” was that it was an interference engine, and better do it before I break a belt and it grenades. For some reason I had it in my mind this entire time that the V6 was not an interference engine, perhaps because of the chain vs belt longevity.

I’m basically at 203k miles, but everything appears to be running well.

I’m going to add on...I took the timing components to work today and measured with something (blade micrometers) besides a set of calipers with short jaws that won’t reach far enough.

The crankshaft sprocket is right at the wear limit, but everything else is well above the tolerance for wear. I have a new one coming in because it’s cheap enough and I’m curious just how much bigger it will be.