Yes, I've always been aware of that, but to me it's still the same general engine in the same engine family at the same displacement. If someone truly knows the exact nitty-gritty of how significant the changes are, exact measurements and all, I'd be interested. Such as how significant the block changes actually were.

In reliability discussions, generally nobody separates the single VVTI and dual VVTI 4.0L's as to be considered independently; we're all pretty comfortable putting them all under the 4.0L umbrella.

At one time I researched the differences. IIRC they shared some common bearing shells.

The Dual VVTi block had improvements for cooling, the liner cross-hatching was improved, and they were more securely attached to the block casting.

So while the Single VVTi 1GRFE, and Dual VVTi 1GRFE, are both 4.0 liter V6 Toyota engines, they share almost nothing in actual parts.

I find that most people, especially if they aren't Toyota enthusiasts, are unaware of that.

Well looks like some good news from Blackstone anyway. All readings are below average. That with the inspection I did with endoscope is really pointing me towards over all OK inside TC at least. I'll be doing another oil change soon to see what shows up and will check with magnet and see what's on the drain plug.

I'm pretty certain I've got the annoying whining idler gear issue and that my accy belt pulley's are starting to go bad. Double checking that and will replace if they need it. The TC idler gear is just a bummer but seems like many have this and have 150-300k miles on the engine. Shame to do the work to crack the front cover to replace a $20 part and possibly have the issue return in 40k.

Feeling a little better. Gotta say seeing the metal flake in oil and hearing some interesting sounds really had me stressing for a bit. I'm hoping all is well. Truck has really good maintenance records and low miles so would be sad to think there's a major issue.

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It’s easy to release tension on the serpentine, spin the idlers and pull if necessary. I got a set when Toyota had a 25% parts sale. This year I splurged for a full tensioner that I hope I never need.
This is the pdf for changes on the 1GR-FE:

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1GR-FE-Engine.pdf (734.9 KB, 40 views)

Early in ownership, especially when driving on hilly roads, I couldn't help but notice how bad this engine sounds from inside. It made me seriously consider different headers but I didn't want to deal with warranty challenges. You get used to it, but never happy about it IMO.