Scotty from what I saw, knows little about hybrids. Just saying.

 

That may be so, but I do like this specific comparison to a 90's era Celica, the bulletproof era, where he shows the water pump separated from the engine. This allows much easier access and lower repair bills, at higher initial costs due to the water pump needing its own belts and pulleys, but at least this shows one specific reason why cars during this time period were so reliable. Catastrophic valve damage due to chain failure is a very real danger to higher mileage vehicles, although I don't see it anywhere in the Avalon maintenance manual which covers up to 120,000 miles, not sure what that means.

 

What! Timing chains are scary! It's not like Toyota's have been using them since 2001 if not earlier 🙃 . By the time any timing chain goes bad, someone would have severely neglected the engine. You don't change the timing belt unless it is out of spec or if you are well over 250,000 miles by which point you are due for a engine overhaul anyway. The timing chain snapping is the least of your worries. In addition, the water pump is electric motor driven. Not engine driven as far as I know. I suggest doing a bit more research on the A25A.

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The major parameters of A25A-FKS 2.5 D-4S Engine - bore/stroke, power and torque, oil specs and capacity, the main problems and advices to prevent them.

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I didn't know the water pump has its own motor, I assumed it was engine driven based on where it was the referenced in the diagram. I would love, love to hear the details on "the timing chain snapping is the least of your worries". What else, please tell, can cause catastrophic engine failure, and will fail well before the timing chain?

 

Also, this is not pic of hybrid engine, as hybrids do not have alternators.
Maybe it should've not even been used as ground for concern.

 

I already said I was wrong about the water pump, the concern about the timing chain and bent valves however is still there, I already referenced a few examples of that.

 

There is nothing new about timing chains. They don't break without reason and there are not many recent instances of timing chains breaking. Don't worry about it. Do your basic maintenance and you will be fine, stop overthinking this.

 

I have driven A LOT of cars and more specifically a lot of Toyotas. I’ve been around Japanese cars a long time. Yeah I’m sure there’s an example of anything failing but a Toyota timing chain is not gonna just snap for no good reason. Trust me you will be bored of the car before something that serious breaks. My 08 Camry Hybrid still has the original factory brake pads.

 

Not snapping.
Stretching. Also, tensioner failing.

 

Folks those of you who are worried about timing chain. I had Mercedes (not exactly a pinnacle of quality) OM606 Engine with 345k Miles with original chain when sold.
Change oil in time and drive the nice Toyota car you have worry free.

 

I was just reading that a new, improved engine oil spec is coming, API service SP. Designed to deal with two issues related to direct injection on gas engines. One of the two issues is timing chain wear, resulting, IIRC from increased soot in the oil. I still would take a timing chain over a belt each and every time.

 

Don't complicate this by mixing "science" in. All they want is to sell more expensive oil under any pretext. Chain is made out of metal. Metal 1. expands as it heats up and 2. stretches under tension and 3. tiny little holes for links it it wear outover the time. On chain, that has easy hundred or more links, you have eventual cumulative effect, when tiny dimensional changes add to overall noticeable result. This is what tensioner is for. GDI or conventional engine. Don't matter. The higher compression engines they use, to compensate smaller size (smaller engine is cheaper to make), the higher is stress on chain.
KISS.

 

Don't complicate this by mixing "science" in. All they want is to sell more expensive oil under any pretext.

So, there is a conspiracy among the auto manufacturers (i.e., ILSAC) to make oil more expensive. And they create fictitious issues with the engines they manufacture in order to justify the more expensive oil (of which they are a major consumer) intended to solve the issues.

To do so, they falsely assert that the oil they specified at the time of manufacture was not up to the job of protecting the engines they built. Brilliant plan! And yet I find myself paying less for oil than I did 10 years ago...for a higher quality product.

If I were to follow this type of logic to its conclusion, I would disregard the Toyota maintenance schedule and use the opposite of their recommended fluids. After all, Toyota must just be trying to sell us more and more expensive cars by making our current ones wear out faster.

 

No oil will substitute for metal fatigue under tension. Oil is lubricating agent, not stretch preventing agent. Metal stretches, period. Tensioner compensates, period. Guides ensure proper chain channeling. Period. If tensioner leaks oil out or, does not have dog on it to prevent recession, after it expanded (Nissan makes them like this), at start up, tensioner will permit chain slap, until it extends. It is very basic mechanics and no oil lubricity magic will help here. No conspiracy, only simple How It Works.

 

So, you still running that SA oil in your cars?

What is colloquially called chain stretch is not actually any significant lengthening of the metal parts. It is wear of the pins and rollers from friction, causing the chain length and spacing to increase. Improved lubricity reduces the friction, reducing the wear, reducing the stretch.