When Should I Change Timing Belt (Age Or Miles)?

[bobstoc]

When should the timing belt be replaced?

I have heard both theories : Change the timing belt according to age AND/OR change the timing belt according to miles. I have a 2004 LS430 Ultra with 51k miles. When I asked my mechanic (at Lexus Dealership), he said, "Don't change it until 90k or so". But, I've also read you should change the timing belt at 6-8 years.

I'm not going to hit 90k miles for some time and I worry about the infamous timing belt failure. Any suggestions?

[billydpowell]

90k miles, or every 7 years, what ever comes first... your manual should tell you this, if you have one, if not, get one for Christmas.. Cheers.

[1990LS400]

It's 90,000 miles or 6 years - sorry Billy. I waited an extra year on my 2000 LS400 and had the timing belt and all the ancillary parts replaced on July 31, 2007 just before 90,000 miles - exactly 7 years to the day after the in-service date. I wouldn't have waited any longer based on my previous experience. It's not the timing belt that breaks. Much more often it is one of the ancillary parts - idlers, tensioner, water pump - that fails and takes out the timing belt. In fact, I've never heard of a Toyota or Lexus timing belt break due to wear. In every case it has been due to the failure of another part.

The timing belt on my first LS400 was trashed in the mid-1990's when the water pump seized at around 75,000 miles - which, of course, was just after the power train warranty had expired.

I am supprised that someone at a Lexus dealership would tell you to wait until 90,000 miles. If you are the original owner continue to pile up miles at the current rate, that could be another five or six years. But, of course, if the timing belt system does fail, the dealer gets to charge you $5,000 to $10,000 when the engine valves get friendly with the pistons.

[landar]

Imagine you are a Lexus engineer and the boss asked you to estimate how long the timing belt is going to last. You do some figuring and come back with 180,0000 miles or 12 years whichever comes first. "Good" says the boss. "Just to cover our behinds, we are going to cut everything in half".

So, its a made-up story but the point is this: Lexus has to make a recommendation based upon knowing nothing about your particular driving conditions, driving habits, climate conditions, etc. Its a "one size fits all" recommendation and that is often NOT the case.

My personal belief is that time is much less a factor in belt life than mileage in the average situation. Sure, if you live in the desert, extremely dusty conditions, high ozone and so forth, the belt may deteriorate more than normal. The Lexus schedule is based more on worst case scenarios than on "normal".

I changed my original 98 LS400 @ 94k and 12 years. The belt looked tired but not in imminent danger of breaking. I did quiz a Lexus mechanic about when I should change it and he said 90k miles. He did not even consider the time period. My current 02 LS430 is at 36k and nearly 10 years...still on the original belt and I have no intentions of changing it just yet. And I sleep fine at night. Much more critical is the water pump as Jim mentioned. If that part freezes up, its bye-bye belt, instantly. You should have the coolant changed every 3-5 yrs to keep the pump seals happy.

I notice that the newer Lexus schedule calls for the timing belt to be changed @ 90k miles or 108 months(9 years), whichever comes first. I wonder why they changed the time schedule? Most likely due to statistical data gathered over the years telling them the 6 years was overkill. This is just my opinion of course.

[1990LS400]

I wonder why they changed the time schedule?

Maybe they redesigned the damned tensioners so they wouldn't fall apart and take out the timing belt.

[landar]

Maybe they redesigned the damned tensioners so they wouldn't fall apart and take out the timing belt.

I must have struck a nerve. :whistles:

[curiousB]

As military people would say it is a question of asymmetric risk. That is to not do it, and defer the repair, is to put at risk a ruined engine (for the newer interference type) vs. delaying a $800-1,500 repair (not eliminating it, just deferring it). $5-6,000 risk vs. repair bill delayed...

So it’s easy to see why it would be biased to the safety side of the ledger, Dilbert manager or not.

What is interesting here is the complete lack of cases of report broken timing belts. Given the threads on this subject I would have expected to hear a tough luck story every few weeks. I have yet to hear of a single event. So it looks like these belts are pretty well designed.

That said, the empty feeling of those pistons bending all the valves, and the delightful $Repair$ that would entail is not a good risk reward scenario for any of us.

Morale of the story, just change the belt when needed and live for another day.

[1990LS400]

What is interesting here is the complete lack of cases of report broken timing belts.

Could it be that people who inhabit Lexus forums are enthusiasts who don't let their cars go to hell?

I've seen a number of reports of timing belt failures on ClubLexus.com which has infinitely more traffic than this forum although most of the reported failures I have seen were on gen 1 LS400's where no damage was done due the engine being non-interference. Personally, I have known only two people - other than me - who have had timing belt failures that bent their engine valves. They were not Lexus vehicles - one Honda Civic and one Toyota Camry. The Honda was low mileage and the Camry was at well over 200,000 miles. The Civic owner had the engine repaired for a few thousand $ and the Camry owner retired his car to the pasture behind his house to join some of his other past cars.

I really do think that on newer Lexus vehices, 95%+ of the time the timing belt systems could operate without failure for well over 200,000 miles or 15 years. But in the words of Dirty Harry, "Do I feel lucky? Well, do ya? Punk!". When it gets down to it, timing belt changes are pretty darn cheap compared to the price of repair after a failure. As the old saying goes: "In the end the stingy man pays the most."

[Mike Floutier]

I was wondering about this. My 2002 LS430 is coming up to 300,000 miles and had done 165,000 miles since the last cam-belt change. Also, when the belt was changed at 127,000 miles they didn't change the tensioners OR the water pump so I did think it ought to be done. HOWEVER, I still procrastinated.

One thing that made me wait was getting my wife's Volvo V70 D5's belt done at 90k miles - the old one looked perfect; "why bother" I thought.

So why did I get it changed in the end, well I'll tell you. Every time I change my oil I look at the serpentine aux drive belt and it looks fine. Then, without warning, it just disintegrates!

I can tell you it didn't take me long to arrange to get the cam-belt changed. Yet, amazingly, after 165,000 miles, the old one still looked like new.

I guess one compelling reason to get it done is - If I'm going to keep the car for another 100,000 miles I'm definitely going to get the cam-belt changed at some stage SO it makes a lot of sense to do it now; I'll only have to do it once and think about the peace of mind!

[jaswood]

Imagine you are a Lexus engineer back in the mid-1980'sand the boss asked you to estimate how long the timing belt is going to last. You do some figuring and come back with 180,0000 miles or 12 years whichever comes first. "Good" says the boss. "Just to cover our behinds, we are going to cut everything in half".

So, its a made-up story but the point is this: Lexus has to make a recommendation based upon knowing nothing about your particular driving conditions, driving habits, climate conditions, etc. Its a "one size fits all" recommendation and that is often NOT the case.

My personal belief is that time is much less a factor in belt life than mileage in the average situation. Sure, if you live in the desert, extremely dusty conditions, high ozone and so forth, the belt may deteriorate more than normal. The Lexus schedule is based more on worst case scenarios than on "normal".

I changed my original 98 LS400 @ 94k and 12 years. The belt looked tired but not in imminent danger of breaking. I did quiz a Lexus mechanic about when I should change it and he said 90k miles. He did not even consider the time period. My current 02 LS430 is at 36k and nearly 10 years...still on the original belt and I have no intentions of changing it just yet. And I sleep fine at night. Much more critical is the water pump as Jim mentioned. If that part freezes up, its bye-bye belt, instantly. You should have the coolant changed every 3-5 yrs to keep the pump seals happy.

I notice that the newer Lexus schedule calls for the timing belt to be changed @ 90k miles or 108 months(9 years), whichever comes first. I wonder why they changed the time schedule? Most likely due to statistical data gathered over the years telling them the 6 years was overkill. This is just my opinion of course.

I have GREAT personal knowledge of the maintenance history of a '91, '92(2), and '95 LS400, all with over 200,000 miles, the '95 now pushing 300,000.

The '91 and one of the '92's have had a single timing belt change, the '95, 2 changes. The '95 first at 90,000 miles second at 270,000 miles, that second one only due (might as well) to the water pump failing. I have had a good look at ALL removed belts and NONE exhibited any undue wear, no cracks, etc.

My '01 RX300 is now at 90,000 and I no plans for timing belt change.

Since that engineering "estimate" in ~'85 timing belts have endured many years of harsh use and manufacturing improvments.

[jaswood]

Imagine you are a Lexus engineer and the boss asked you to estimate how long the timing belt is going to last. You do some figuring and come back with 180,0000 miles or 12 years whichever comes first. "Good" says the boss. "Just to cover our behinds, we are going to cut everything in half".

So, its a made-up story but the point is this: Lexus has to make a recommendation based upon knowing nothing about your particular driving conditions, driving habits, climate conditions, etc. Its a "one size fits all" recommendation and that is often NOT the case.

My personal belief is that time is much less a factor in belt life than mileage in the average situation. Sure, if you live in the desert, extremely dusty conditions, high ozone and so forth, the belt may deteriorate more than normal. The Lexus schedule is based more on worst case scenarios than on "normal".

I changed my original 98 LS400 @ 94k and 12 years. The belt looked tired but not in imminent danger of breaking. I did quiz a Lexus mechanic about when I should change it and he said 90k miles. He did not even consider the time period. My current 02 LS430 is at 36k and nearly 10 years...still on the original belt and I have no intentions of changing it just yet. And I sleep fine at night. Much more critical is the water pump as Jim mentioned.

If that part freezes up, its bye-bye belt, instantly.

Yes, bye-bye serpentine accessory drive belt, NOT the timing belt.

You should have the coolant changed every 3-5 yrs to keep the pump seals happy.

I notice that the newer Lexus schedule calls for the timing belt to be changed @ 90k miles or 108 months(9 years), whichever comes first. I wonder why they changed the time schedule? Most likely due to statistical data gathered over the years telling them the 6 years was overkill. This is just my opinion of course.

...

[landar]

Yes, bye-bye serpentine accessory drive belt, NOT the timing belt.

...

You lost me there. WHY would the serpentine accessory belt go and not the timing belt if the water pump seizes?

The timing belt, not the serp accessory belt, drives the water pump directly and a seized water pump bearing is either going to (pretty quickly) shred the timing belt or cause the timing to jump a tooth or more if the pump shaft leans to one side as it freezes up (as is often the case).

[jaswood]

Last I knew it was the serpentine belt that drives the water pump.

[1990LS400]

Last I knew it was the serpentine belt that drives the water pump.

The timing belt drives the water pump on all Toyota/Lexus models with timing belts I've dealt with.

As I have recounted numerous times on this forum, the timing belt on my first LS was trashed in the mid 1990's when its water pump seized at about 75,000 miles. I had left my house on the way to work a couple of minutes before it happened, thought I smelled coolant, and then BANG! I was fortunate to be able to coast the car into a convenience store parking lot.

[LXPearl]

I had a timing belt break on an 85 Camry that I bought new. I believe it went out before 70k miles (rated 60k). I was in Texas then and the engine was non-interferance, so the repair was easy. It left me stranded on the freeway at night on my way home - not pleasant. The new timing belts are for 90k and Toyota seems to be making them better. I have heard consistent 150k miles reached. The hot & dry SW USA probably needs changing closer to the 90k.