as always, someone has to be different 
“As with some of Ford’s other recent small engine implementations, the belt is sealed and immersed in oil to reduce friction, reduce noise and increase the service interval. An inspection is called for at 150,000 miles, but Ford expects the belt to last the life of the engine. That’s great if they are right, but the replacement will be exceptionally complex if they are wrong.”
Any engine with variable valve timing is an interference engine. So pretty much any OHC engine made in the last 10 years will be of the interference type. Engines using the same block have gone from non-interference to interference when the heads were updated to include variable valve timing.
GM OHV truck engines might still be non-interference, but LS and new Hemi engines are.
EDIT: Nah the newest GM trucks all have VVT so they probably are all interference now.
Not so.
For one, the GM 3.5-litre pushrod variable-valve-timing overhead-valve engine with a timing chain is not an interference engine.
Follow the manufacturer’s recommendation.
This isn’t a suggestion akin to “clean your windshield before starting a long road trip”.
If your timing belt breaks while the engine is running, you have a good chance of having a downward moving opening valve (or two) make contact with an upward moving piston head (or two). An undesirable possibility. Known to kill an engine by causing more damage than is economical to fix.
3.3l is not an interferance motor. Son in law just had the water pump pully fall off while going down the freeway breaking the belt. It only had 20k since belt and pump change. New pump and belt and it runs great. That was on mothers day. Found a listing somewhere that had all toyota highlander v6s as noninterferance
It’s a good thing you mentioned that, I’m not sure the OP has been told yet.
Oh yeah. Well aware of that. I’ pretty sure it’s an interference engine, so a belt break would be bad news.
Sorry but the Toyota factory engineer I just asked about this disagrees with you.
While Toyota doesn’t publish a list if interference vs. non I’ll take his level of experience over yours.
FWIW, the Gates timing belt guide (huge PDF link) says it’s not an interference engine.
Toyota has never been very big on interference engines (unlike Honda) and at least if the Gates guide is to be believed the only interference engine with a belt they’ve made this century is the 4.7L truck V8.
Thanks Jack. Guess it’s not an interference engine. ~ enipla
on some engines (like my previous SRT-4) the valves won’t be struck by the pistons, but there’s a chance the intake and exhaust valves can strike each other (and bend) if the cams go out of sync in a certain manner.
edit: oh, and also even on a non-interference engine, you can still have a valve-piston strike if the belt lets go at high engine speeds.
Off the top of my head both the 2JZ-GE inline 6 with VVT and the UZ V8s that were used since the original LS400 are interference engines with belts. It’s probable that these were only used in Lexus branded vehicles and not Toyota branded ones in the US market.
enipla, I’m pretty sure Joey P was being sarcastic since it was mentioned at least three other times earlier in the thread before TallTrees made his post. It’s apparent TallTrees hadn’t read through the entire thread before posting.
The Toyota factory repair manual for this engine specifically warns of the possibility of a valve piston strike in the timing belt replacement instructions. That coupled with my conversation with a Toyota factory driveline engineer has me doubting the accuracy of the Gates guide.
Sorry but I have to go with the factory on this one.