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What's A Good Idea When Replacing A Timing Belt

I am ready to have the timing belt on the '03 Avalon replaced. A friend suggested also doing the following replacements: water pump, tensioners, cam seals, crank seals and thermostat. Anyone in the community with a thought on this? Thanks. I appreciate the insight(s).

How many miles on it? I susbscribe to doing the water pump at least with every other belt change. The tensioner can be tested, but I can’t fault anyone for changing it when the pump is changed. I don’t think the cam & crank seals should be changed unless they’re leaking. The T-stat should be fine, although some believe in changing them out occasionally and while the coolant system is drained (when the water pump is being replaced) is as good a time as any.

Others here will have different preferences. Some things just aren’t “black & white”.

i would do the water pump far as the rest of the stuff is this the firast time the belt is been done or the 2 nd time

Timing belts now come in kits, such as this.

Buy the kit and do the job right.


Your friend has excellent advice. If you’re taking off the timing cover anyways, you should make sure everything under there is new and good to go for another 60K

@Tester has the right idea. Buy a kit. For your car I recommend Aisin or Gates.

it is also a good time to start fresh with new coolant.

the same mountainbike: “I susbscribe to doing the water pump at least with every other belt change.” How long do you keep cars that there’s an “every other” timing belt change? Assuming 100K change intervals, does that mean you change water pumps at 200,000, 400,000, and 600,000 miles?

Anyway, there are shops out there that, when the timing cover comes off, everything under there gets replaced. There are other shops that will just replace the belt. My opinion: a water pump can reasonably expected to last 100K miles without failing. But 200K? Well, not really. If you only replace the belt, there’s a chance that 40,000 miles from now the water pump may start leaking or the timing belt tensioner may fail. The odds of failure are greatly reduced by replacing all moving parts at the timing belt service. And if one of those parts do fail, you’ll be paying for the job all over again, plus the inconvenience of a broken car. Have your mechanic use a timing belt component kit as posted above and be done with it.

As for the thermostat, your call. It’s not part of the t-belt service.

Good point, ASE. Changing the water pump and tensioner every 100,000 miles is prudent. My mind was thinking of the old standard of 60,000 miles between belts. You’re right.

Since the system is drained to replace the water pump, some like to change the T-stat too. I’ve never changed a T-stat unless the engine has been overheated or the T-stat has failed, but for the price it’s worth it if it helps someone sleep better.

The Avalon in question has 85,000 miles on it and manual suggests @ 90K. So it is the first time for the time belt change. Thanks, again.

Most timing belts have a time limit too…Usually no more then 7 years. So you’re way past due.

Other than agreeing with the premise of getting everything in one shot to avoid future problems, I might add in regards to the thermostat that I consider them a maintenance item that should be replaced on occasion; say every 5 years. That would be in addition to replacing them on any new engine, head gasket job, etc, etc.

Many an engine has been ruined because of a lowly 5 dollar thermostat that suddenly decided to go south and the car owner kept motoring; aware of the temp gauge or not.

My 2005 Camry has the 1MZ-FE V6. Same as OP
My maintenance book says to replace the timing belt at 90K/108 months

OP’s book says 60K/72 months.

For 2005 Avalon, the book says 90K/108 months.

May we assume that Toyota started sourcing better parts in 2005?

Or perhaps the engine was “redesigned” so that it wasn’t as rough on belts?

In all honesty, I assume it’s all about marketing.

My opinion is that it’s all about marketing; nothing more.

My feeling is that it’s about the engine, perhaps how many bends backward and forward it needs to endure. And perhaps how tight the radii are. But maybe I’m being naieve, maybe it truely is just marketing.

If it was just marketing…then it’s either one of two things.

. The old recommendation of a 60k interval change was way too conservative.
. The new recommendation is exceeding the life of the belts and we should be seeing major increases in broken timing belts and destroyed engines. Marketing doesn’t defy the laws of physics.

I suspect it’s the design of the belt that’s increased the change interval.