I have two Toyotas.
One is a 1999 Sienna with 75,000 miles.
The other is a 2002 Corrolla with 110,000 miles. Do I really need to change the timing belts? I have maintained both cars well but this is expensive and I’d rather not spend the money if I really don’t have to. Both cars run well. Also - if I do need to do this, is this something my mechanic can do or should I go to the dealer? Thanks.
If the belt breaks on the Sienna, you will be stranded right then and there. Even if it’s in the center lane of an Interstate surrounded by semis. Or in the middle of nowhere in the middle of the night. Then you’ll have those fun scenarios to deal with in addition to the timing belt. Find an independent mechanic and get it done, along with the tensioner and waterpump.
The Corolla has a timing chain, which doesn’t require replacement until it stretches. It could very well last as long as the car.
Also, if the Sienna has an interference engine you will be looking at extremely costly engine work to repair the damage done to the pistons and valves if the belt breaks.
I agree with both of the above posts, but I want to make a slight revision to nfs480’s response. Instead of “if the belt breaks”, the reality of the situation is WHEN the belt breaks.
When will it break? Nobody can predict that, but the schedule for replacement that Toyota has provided should be adhered to, if you want to avoid this type of mechanical failure.
Timing belts do not give any warning signs prior to snapping, and as one of the most knowledgeable members of this board has said, “Your engine will run very nicely, right up to the nanosecond after the belt snaps”. When it snaps, pistons and valves will collide, causing bent valves and “nicked” pistons, thus necessitating that the engine be disassembled for repair.
If you compare the cost of the proactive belt replacement (as specified in the maintenance schedule provided by Toyota) with the cost of replacing valves and possibly pistons, the importance of this maintenance procedure should be obvious. And, as NYBo stated, your water pump should be replaced at the same time, along with the timing belt tensioner.
According to the Gates site, it’s not an interference design.
Okay, that is good in terms of lesser financial consequences for the OP when that belt breaks. Now, as long as the OP does not mind the other factors that you mentioned in your first post (being stranded, being “powerless” in the middle lane of an expressway), then the OP can proceed to drive the vehicle into the sunset.
look in your owners manual. it will have the timing belt replacement paragraph in there.
it should be based on mileage and years.
the good news is your sienna is NOT an interference engine. this means that when it breaks your engine won’t be trashed. BUT, rest assured you are at risk for being stranded when it does break.
so it is up to you. do you gamble? are you willing to risk being left a long way from home?
at some time, the cost of repairs is outweighed by the risk of being stranded . it’s your choice.
Here is a link to timing belt discussions on a Sienna forum.
The gist is that early Sienna motors were non-interference, later models (~2001) with VVT-i (variable valve timing) are interference. The Gates guide I have lists all Siennas 99 to present with interference models. The interval on my 2006 is 7 yr/90k based on the Owner’s Manual. At 9 years on the original timing belt, you’re probably on borrowed time. If you’re planning on keeping it, I would get the belt and water pump changed.
Ed B.
Make one of the requirements of your next vehicle be that the engine is of non-interference design,camshaft(s) not be belt driven and the water pump drive is not incorporated in the drive for the valve train. You could also consider buying a car that scheduled maintiance is included in the purchase price.Or lease or sell before any of these timing belt,water pump,interference engine issues are due for attention just some ways to lower maintiance costs,but you pay more upfront
Those criteria would certainly narrow the field, unnecessarily so. Most high fuel economy vehicles would be eliminated, for example.
But I like the idea of a timing chain, having replaced timing belts on transverse V6 engines.
Do you absolutely have to replace the belt? Yes. It’s just on what terms - your’s or the belt’s. You’re going to pay for it sooner or later, might as well do it before it breaks than after. So replace the f***ing belt (there, Cappy, is that more legible for you?)
Funny thing is, when I bought my Camry, IIRC the 6 cyl had belts but the 4 cyl is a chain. This played a role in my decision to buy the 4 cyl version.
There are two universes for car care. There are owners who keep up maintenance somewhat religiously, always hoping to avoid break downs. Then, there are owners who insist IF IT AIN’T BROKE, DON’T FIX IT… And never the twain shall meet.
lol, yup
“Then, there are owners who insist IF IT AIN’T BROKE, DON’T FIX IT.”
I always wondered who those people were who were parked on the side of the road with the hood up, waiting for a tow truck!
Seriously though, I used to know someone just like that (if it ain’t broke, don’t fix it) and he had the most incredible record of being late for social engagements, work, church, etc. because his car was so unreliable.
No matter how often others would try to inform him of the need to maintain his car, he would resist. Finally, after being stranded on a remote country road during a heavy snow storm (in the era before cell phones), he finally began to get the message. Some people are just slow learners, I guess.
Anyway, your comment was very well expressed, Rod.
“The Lord looks after fools and children,” often comes to mind when dealing with the latter group. Somehow they seem to stumble through life, complaining they got a lemon.
Yup!
When the inevitable happens, it is always some else’s fault.
My pet peeve with society today is the rampant failure to accept responsibility for one’s actions. And, in a similar manner, when people don’t act appropriately, it seems that they always blame the consequences on someone else.
Whatever happened to personal responsibility?
Ask the lawyers. 
To the OP, it can be expensive now, or it can be REALLY expensive later.
I have a 1999 Sienna. Did some research found a couple conflicting indications that the engine is or is not an interference engine. The guy I bought it from says it is not an interference engine. But even the Gates website contradicts itself. It has 182k miles and runs really well. The guy I bought it from had bought it a few months earlier from a guy that replaced the Sienna with another vehicle. He had always maintained well, but don’t know if he had replaced the timing belt for sure. I suspect he had, but don’t want to take any chances.