Timing Belt Question
10-06-20, 02:28 PM
#1
Driver School Candidate
Thread Starter
Timing Belt Question
Hello All -
I recently purchased a 2004 GX470 with only 72,000 original miles on it. The timing belt was changed in 2012 with 40,000 miles. I am wondering if it needs changed again now that it has been another 8 years, but only 32,000 more miles? I have read in some places that they last 7-10 years regardless of mileage. Should I get it changed now or hold off? Thank you!
I recently purchased a 2004 GX470 with only 72,000 original miles on it. The timing belt was changed in 2012 with 40,000 miles. I am wondering if it needs changed again now that it has been another 8 years, but only 32,000 more miles? I have read in some places that they last 7-10 years regardless of mileage. Should I get it changed now or hold off? Thank you!
10-06-20, 04:04 PM
#4
Lexus Fanatic
Welcome to CL as a new poster. 
After 8 years, regardless of mileage, I'd change the belt. One thing you don't want is it snapping on you, particularly if it is an interference-engine, which can be damaged by valve/piston contact.
I never liked the idea of timing-belts.....IMO they are a PITA. Automakers used them for a while because they were cheap to produce and made the engines run quieter, but went back to oil-bathed chains for a reason.
Some technicians, when the belt is placed, especially on transverse-mounted engines, also recommend replacing the water pump as well, because it can be difficult to open up the front of the engine when it is mounted transversely, and it is easier and cheaper to both at once. But, with the truck-based GX and its fore/aft engine mount, that is less critical, because it is easier to service the front of the engine.
After 8 years, regardless of mileage, I'd change the belt. One thing you don't want is it snapping on you, particularly if it is an interference-engine, which can be damaged by valve/piston contact.
I never liked the idea of timing-belts.....IMO they are a PITA. Automakers used them for a while because they were cheap to produce and made the engines run quieter, but went back to oil-bathed chains for a reason.
Some technicians, when the belt is placed, especially on transverse-mounted engines, also recommend replacing the water pump as well, because it can be difficult to open up the front of the engine when it is mounted transversely, and it is easier and cheaper to both at once. But, with the truck-based GX and its fore/aft engine mount, that is less critical, because it is easier to service the front of the engine.
10-06-20, 05:06 PM
#6
Lexus Fanatic
10-06-20, 05:26 PM
#7
I bought my ‘06 Tundra with 4.7 V8 almost 7 years ago (with 79k miles, but I’m fairly certain the previous owner rolled the odometer back). Since I decided to keep the truck for a while, I finally had the timing belt changed last year (at around 165k). It was pretty bad (cracked up all over), but assuming it was never changed before, it held up surprisingly well.
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10-06-20, 06:18 PM
#8
Lexus Champion
10-07-20, 11:54 AM
#9
belt age is also dependent on ambient temp and humidity on top of mileage and time. if you look at your serpentine belt, likely your timing belt will be in the same condition. use only as a quick check and shouldn't be the golden rule as the timing belt is more internal protected from dust and debris.
what i've seen is that the idler or tensioner pulleys are the first to fail (seized bearings), taking the belt with it! i've ran on over 130k on the original belt and all it had were cracks (1UZ on my LS400 - typical belt change is every 90k interval). to me it likely wouldn't have snapped even with the cracks on the surface. iirc the idlers had play however so it was on borrowed time!
if it were my car, i would make sure the idlers were replaced at the same time as the belt (and water pump too). if so, then i would drive it until 90k interval. if not then i would do it all for my peace of mind!
what i've seen is that the idler or tensioner pulleys are the first to fail (seized bearings), taking the belt with it! i've ran on over 130k on the original belt and all it had were cracks (1UZ on my LS400 - typical belt change is every 90k interval). to me it likely wouldn't have snapped even with the cracks on the surface. iirc the idlers had play however so it was on borrowed time!
if it were my car, i would make sure the idlers were replaced at the same time as the belt (and water pump too). if so, then i would drive it until 90k interval. if not then i would do it all for my peace of mind!
10-07-20, 04:22 PM
#10
Pole Position
The question of TB interval can only be answered by oneself. Are you risk adverse, or do you like to gamble? Is your vehicle well taken care of, or driven hard and put away wet?
That said, I've replace four Toyota TB's myself, most long past their recommended change interval, and I'm always pleasantly surprised at how well the belts had held up, with most looking like new, even after 140K on one of them. So, I'm fine with stretching the interval by 30-50%. In a lot of cases, one of the other components that gets replaced during a TB job fails before the TB does, so waiting for a water pump or pulley to go lame is a good time to the job. But that's just what I'm comfortable with.
That said, I've replace four Toyota TB's myself, most long past their recommended change interval, and I'm always pleasantly surprised at how well the belts had held up, with most looking like new, even after 140K on one of them. So, I'm fine with stretching the interval by 30-50%. In a lot of cases, one of the other components that gets replaced during a TB job fails before the TB does, so waiting for a water pump or pulley to go lame is a good time to the job. But that's just what I'm comfortable with.
10-08-20, 05:34 AM
#12
I have never had the timing belt changed on my bought-new 2004 Lexus ES 330 with 155K+ miles.
I follow the Owner's Manual -
LEXUS MAINTENANCE SCHEDULE
1. Every 5,000 Miles or 1 Year - Oil and Oil Filter Change
2. Every 30,000 Miles or 3 Years - Air Filter Change, Cabin Filter Change, Wiper Blades Inserts Change, Check All Hoses and Belts
3. Every 100,000 Miles or 10 Years - Coolant Change
I follow the Owner's Manual -
LEXUS MAINTENANCE SCHEDULE
1. Every 5,000 Miles or 1 Year - Oil and Oil Filter Change
2. Every 30,000 Miles or 3 Years - Air Filter Change, Cabin Filter Change, Wiper Blades Inserts Change, Check All Hoses and Belts
3. Every 100,000 Miles or 10 Years - Coolant Change
10-08-20, 09:57 AM
#13
Lexus Fanatic
You are on borrowed time especially if you do mostly city driving. I've seen a Toyota timing belt go 240,000 miles but the car was 90% freeway driven, the rev up/down cycle stresses the belt much more.
10-08-20, 10:21 AM
#14
Lexus Champion
My dad used to work parts and service at a Toyota dealership and he always drilled in to me to have the timing belt replaced on schedule, as they would get cars towed in quite frequently where the timing belt had snapped.
10-08-20, 12:29 PM
#15
Lexus Fanatic
Timing belts that snap are not a huge deal if they are non-interference....LS400 is a non interference....on the other hand, if my 4.7iForce goes, my engine is in BIG trouble.