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Lexus 1999-replace an unbroken timing belt?

I have a 1999 Lexus with 120,000 miles on it. During it’s recent oil change/checkup, the mechanic recommended that I replace the timing belt, even though it doesn’t show sign of breaking ‘…because Lexus recommends replacing the belt at 100,000 miles.’ He said, ‘I’d hate to see you caught on the highway somewhere with a broken belt.’ I usually adhere to the ‘If it ain’t broke don’t fix it’ rule, but because he’s very honest and reliable, he’s got me worrying. Any thoughts?

Change the belt or spend a lot more money repairing the damage when it breaks . He’s telling the truth .

You need to check to see if your car has an interference or non interference engine. If it’s non interference you could run it till it breaks if you want to eventually end up stranded, if it’s an interference engine you need to take the mechanics advice or you’ll likely end up doing significant damage to the engine. Lots of times the belt doesn’t look bad, but will crack where the teeth are made into the belt causing it to strip some of the teeth off. If your water pump is driven by the timing belt you should also change it while the timing belt is being changed, because if it goes out before the next timing belt change interval you’ll be paying double.

I recently changed the timing belt on my '02 Escort (115K miles) that has a 100K mile change interval and when I got the belt off I could see it was beginning to crack at the teeth so it probably wouldn’t have gone much longer. My engine is non interference so I wasn’t extremely concerned about it if it broke. On one of my other cars with a non interference engine I’ve had a couple timing belts strip teeth off before 100K miles.

Change it, interference or not. Your engine will immediately stop running when it breaks, and it could be at a very inconvenient moment. No reason to gamble on this.

You need to open the owner’s manual and start following the maintenance schedule. If it ain’t broke don’t fix it doesn’t work with machinery - which has to be maintained or it falls apart and ends up costing more in the long run.

You’re actually very lucky that the belt is still intact since you’re overdue both according to mileage and time. Picture this scene: you’re tooling along on 3 lane, 70 mph highway with one tractor trailer on one side and another right behind you when your car very suddenly stops running with no notice whatsoever. It will not make any noise; nothing will “look” like it needs to be changed; the car will do nothing funny beforehand. It will just die. Now you can’t speed up or maintain speed. You lose power to the steering and very shortly after that power to the brakes. If you live through this and are able to get a tow you find out the next day that your engine is destroyed and you need a new one. Its not fun.

Using the “if it aint broke, don’t fix it” method with a car is a very bad way to go. With your car it can be more expensive to have the repairs after a broken belt than to just have it replaced now. If it is an interference motor, you can do damage to the pistons, valves, cylinder block, crankshaft, connecting rods, cylinder head, and these will be much more expensive than just replacing the timing belt alone.

“even though it doesn’t show sign of breaking”

It will ‘look’ just fine until it breaks (or the teeth come off).

The belt is 13 years old. What’s a miracle is that it hasn’t broken long ago.

You changed the oil even though it wasn’t broke yet. You could have waited until it was completely broken down and then done the oil change.

For a lot of things, I to have gone from the Red Green philosophy of “If it ain’t broke, keep fixin it till it is” to the “If it ain’t broke, don’t fix it.” But that does not apply to oil (engine and AT), coolant or timing belts.

You’re overdue.

Texases is right. Or risk finding yourself standing on a barely existant shoulder in the middle a very busy road against a Jersey barrier on a dark and rainy night. In a bad part of town. A strange town. With a crooked garage.

The GS400, LS400 and SC400 have interference engines. The ES300, GS300, and SC300 do not. You won’t destroy the engine in the 300 series if the belt fails, but you will in the 400 series.

On the water pump, find out what the manufacturer recommends on changing that. On my Toyota Sienna, they recommend “inspecting” it. At 90,000 miles mine was okay, and now it has 178,000 or so. I will get the water pump changed this time, because of the high mileage, but my car has a very long lived water pump, not like some cheaper models. So, on other models with ordinary grade water pump, it makes sense to replace both.

On the other hand, due to your low mileage driving, it would be a long time before you replace the timing belt again. So, yes, it might be a good idea to replace it now. Brace yourself for a shock; this costs money. But, it is part of normal maintenance on a car. Cheaper than a new one by far.

Also, if you haven’t kept the cooling system well maintained, it might be correct to replace the water pump now. If you don’t and it fails, it could get expensivev.

Listen to all these naysayers. Our economy is in bad shape and the mechanics need the money. Since you’re driving on an old car, look at all the money you’ve saved over the years! I’m still saving. My car is 23 years old with 180,000 and I haven’t changed the belt yet either. Play the odds!

You never know when it might break (or skip a tooth). When it does, it may stop the engine right now, which means your car is going to stop rather quickly and that can be the cause of an accident.

Remember recommended change intervals are usually XXX Miles or XX months which ever comes first.

dtracy. I’m pleased that you’ve hung on so long without doing the necessary preventative maintenence, but what you’re suggesting is neither sound automotive advice nor sound financial advice. At an average of 3,000 rpm, your timing belt has wound its way around its sprockets and pulleys 540 million times. You’re beyond pushing your luck. Should it fail on an interference engine, the pistons will bang the valves and as a minimum bend a few valve stems and put dings in the pistons. Dings become hot spots and concentrated stress spots and can lead to other failures.

I support your right to take your own risk, but what you suggest is bad advice.

People who play the odds play the odds knowing what they are doing. So what are the odds? I’d give the odds of making it 23yrs / 180K on a timing belt as pretty low. Don’t mistake lucky with smart.

Of course, we don’t know what kind of mystery vehicle dtracy drives, so for all we know it has a timing chain.

Excellently stated, Cig. And an excellnt point about not knowing what dtracy drives.