Timing Chain Tensioner Location

There was a pretty decent DIY on this forum - for a 2001 Chevy Prism, but the work is essentially identical for all 1ZZ-FE engines.

https://www.corolland.com/forums/index.php?/topic/23007-1zz-fe-timing-chain-tensioner-diy/

Dom's right - usually the tensioner is fine, just the o-ring shrunk, causing it to leak. If you have a difficult time finding the right o-ring or don't feel the tensioner looks right - just replace the tensioner. From the dealership + o-ring, set me back about $28. Many have been able to get that even cheaper.

You don't have to remove the valvecover - though usually, when the tensioner starts leaking (most after 100K miles) - might be worthwhile to remove the valvecover and replace the grommets and o-ring around there as well. The valvecover may not be leaking yet - but since you are right there, might as well change them. Allow gives you access to check valve clearances - let you access the condition of the the end of the engine as well.

Replacing the tensioner is pretty much plug and play - the only tricky part is getting the tensioner to release the plunger from the "hook". Once you look at some pictures of the tensioner, you'll understand. Having the valvecover off - you can visually see the plunger release as well as hear it snap in position.

If you feel uncomfortable in removing the valvecover - you can easily do this with the valvecover in place - just have to wiggle the crankshaft back and forth to dislodge the hook and listen for the popping noise.

As for timing chain lifespan - as long as you stay on top of the maintenance - should last the life of the car. There is no set replacement interval on the chain - just audible checks. Note that this is an interference engine - so when it lets go, valve damage is very likely. Should you be worried - nope - just change the oil on regular intervals and note any unusual or excessive chain noise. Proactively replacing the chain is no guarantee that you will avoid chain breakage. Could be a sprocket that loses teeth, or the chain guides wearing out and eating the chain, timing chain tensioner could get stuck and wear out the chain or put too much slack in it. Once the engine gets up to 200K or 250K miles - then I'd say it be worthwhile to tear into it and see if the chain is overly stretched out. Remember that there have been a number of 300K+ mile Corollas with the original chain still on there. I wouldn't worry too much about the chain.

Sounds like you got the gist of it. Valvecover off is by choice - you can do it with it still on, just have to make sure you hear the "click" or "pop" when the hook unlatches from the plunger. Definitely don't want to start the car if the tensioner is not "open". I forget how many bolts there are on the valvecover - but there quite a few. Some may not be 100% obvious, as they could be holding down a bracket - one of them is the stud that attaches to the plastic engine cover. Generally recommended to always replace the o-ring and grommets on the valvecover when it is off. Also, you need to put a dab of FIPG material on the joint between the head and timing cover. It will be pretty obvious, as there is likely to be a big glob of stuff on there from the factory.

Before we get too far - is your tensioner leaking? You have close the amount of miles where this might start leaking, but don't change it for the sake of changing it, unless it is already leaking. Some have well over a 100K+ miles with the original timing tensioner still on the car. You gain nothing if this is preventative maintenance - in fact, you could cause damage if the installation was incorrect.

Little different material - FIPG (Form in Place Gasket). Some FIPG are sold as "RTV" but not all "RTV" can be classified as a FIPG replacement. You can get the Toyota branded stuff or get the three-bond or Permatex alternatives for a fraction of the price / exact same stuff. Just make sure it says FIPG material - might also say black silicone or liquid gasket or gasket maker on there. If you can't find any - get the Toyota stuff - part number 00295-00130 - runs about $15-$20 per 3oz.

Correct, the valvecover uses an o-ring - not the old fashioned cork/rubber gasket. So it just pops into a groove on the bottom of the valvecover. For this - I'd stick with OEM parts - since people only tend to replace them every 100K miles or so. Not much difference in price either - I think both run about $20-$25.

Toyota branded stuff is supposedly exactly the same as the Three-Bond material. Can be harder to find - hence lots of people recommend Permatex - heck, I can pick up some of it at Target.

Permatex - I've used those for many applications, no problems at all. Just follow the instructions, remember that a little goes a long way - should be good to go.

Lately - I've been using Permatex Ultra Grey High Torque or Permatex Right Stuff gasket maker - works just like the Prematex Ultra Black, but these setup a bit faster (15 minutes / hour - vs two hours for tack free on the Ultra Black).