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Lexus ES 300 Timing Belt - Interference or not?

Ever since the dealer recommended replacing the timing belt… “before something catastrophic happens” I have been trying to get one simple answer. Does this car have an interference engine or non-interference engine. The Lexus mechanic couldn’t (or perhaps would 't) give a straight answer to this question. He only eluded to the fact that if the belt was to break the piston “may” come into contact with the valves and the engine would be toast. I have done the obligatory web searching and have found that everyone under the sun has a different answer for this. Does anyone out there have a clue?

2003 Lexus ES 300

According to Gates (maker of timing belts) it is a non-interference engine:

While it may not damage your engine, having the belt brake will immediatly shut it down, which could be a REAL problem if you’re, say, in the middle lane of the freeway at rush hour, or passing somebody on a 2 lane road. Just replace it if it’s time.

@texases; my phobia is always the railroad tracks, always try to have enough momentum to just pass the tracks even if the engine dies, not sure if my wife gets it though.


Yes, timing belts do not normally break in your driveway or in a supermarket parking lot. A few years ago we got a panic call around midnmight from one of my wife’s friends that her daughter’s pickup truck had “just quit” on a not so nice dark road. From talking to her it apeared that the timing belt had broken.

I advised her to call the AAA and have the truck towed to a garage in the area, which I had used with good results in the past. Advised her to slip a note through the door slot with my diagnosis and recommendation. She got the truck, a small Japanese model, fixed the next day and finally learned to read her owner’s manual and become more proactive in car care.

Very expensive lesson to learn. It’s a shame that so many people learn it that way.

Technically, you have a non-interference engine. This means that valve damage is unlikely in the event of a timing belt failure, but stranger things have happened. I have seen valves bend from timing belt failure on non-interference engines, and valves remain untouched during timing belt failure on interference engines. This is not the most important point, though. As others have noted, sudden engine failure doesn’t normally happen in the driveway or in another convenient place, at a time you have no plans anyway. Unless you are the stereotypical little old lady who only uses the car to get to church and the grocery store in your town of 1,500 people, never travel, and never drive on the highway, this sudden failure could, and probably will, happen at the worst possible time. What good is an engine with a broken timing belt and no bent valves if it’s in a car that got totaled in a head-on collision while the now-deceased driver tried to pass someone on the highway with a long-overdue timing belt that finally gave out?

Damage to engine or not, a botched towing job could cost you almost as much.

Double overhead cam engines like yours can still experience damaged valves. The cam shafts prevent valve interference when they are operated by the timing belt. But if the belt breaks, the exhaust valves can fall at the same time as the intake valves, causing valve damage. I’d get the belt changed ASAP.