arseatea56

I am getting a little concerned about the serpentine belt in my 2011 ES 350 and whether the engine is interference or not and cannot find the info on the net. Can you tell me for sure whether it is or not. I appreciate your answer. Thanks. arseatea.

xjokerz

You mean timing belt? These cars use a timing chain, which never needs to be changed or serviced. That is if you don't do anything stupid to the car and drive like a lunatic every single time out. Even then I'd bet strongly on the timing chain lasting hundreds of thousands of miles.

Wilson2000

Agreed, but still an interesting question. If the timing chain broke, would the valves crash into the pistons? My guess is yes.

xjokerz

Well yeah, of course some bad things would happen but the odds of that in a Lexus design is almost impossible. I've never heard of a chain break on a Lexus.

Wilson2000

I see your point about Lexus timing chains not being prone to breakage. That said, nothing catastrophic would necessarily happen if an ES chain broke, only if it is not an interference design. Whether or not it is, is dependent on the design objectives. My guess is they used an interference design to maximize performance and efficiency, so, a broken chain would result in the engine becoming a boat anchor. However, if going for maximum reliability, designers might have used a non-interference design.

ESh

2GR-FE is an interference engine. If the timing chain snaps it would do a lot of damage but this engine has one of the best chains out there and it would never snap.

arseatea56

Because of very close tolerances, In an interference engine, if the belt breaks or slips a cog or two, the valves and pistons might be up at the same time, they would meet, and it could destroy the engine. The main reason I ask is when I start my engine, sometimes, I get that whine that we used to associate with a bad fan belt. It only lasts a second or two. The things that might cause a belt to slip or break is a bad or locked bearing in the water pump, ac compressor, or belt tensioner. If the engine is not an interference engine,. then I would be concerned, but not overly. I will have it looked at asap. The engine has 83K on it. They generally look at the belt at 90K, but I will have them check it our a little early just to make sure.

Wilson2000

You are conflating the engine component drive belt with a timing belt. Two things are wrong with this. The drive belt that runs water pump, AC compressor, regulator and power steering pump is prone to slippage and making a "whine" when it gets old, stretched and hardened. However, it has nothing to do with the valve timing and any breakage won't affect the internals of the engine. The other point you are missing is your ES has a timing chain instead of a timing belt, and the chain is not prone to breaking. So, even though the ES has an interference design, it doesn't matter unless the chain breaks. So far, or as far as I know, nobody has reported a broken timing chain on CL.

arseatea56

Thanks. That does answer my question. The only Lexus engine I ever helped change the serpentine belt was a 1992 ES300. The belt had cogs and I believe it drove everything in the engine including air, valves, water pump, tensioner, alt, etc. I do believe the noise I am experiencing is from the serpentine belt and I will have it checked for wear at the next maintenance which will be very soon. I guess worrying about belt breakage is totally unnecessary.

Wilson2000

Not exactly...You do need to worry about the serpentine belt breaking as it will cause overheating very quickly as no coolant will circulate in the engine. Many have ruined their engines by attempting to drive to the next exit or service station while overheating. This turns a $100 belt replacement into a $4-5K used engine swap! If your belt breaks, pull over immediately, shut er down, and have your SC towed to a reputable shop!

arseatea56

Yes. Thanks. I will do that.