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Maximum Life Of The V8 Timing Belt ?


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My 1991 LS400 has 101,000 miles and the timing belt has never been changed. I was wondering

if it might be possible to get another 25,000 - 50,000 more miles of life out of the belt if I drive mainly on the highway and without a lead foot?

Anyone here ever get 125,000 or more miles out of their V8 timing belt? Anyone ever break their timing belt in under 125,000 miles?

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I bought my LS when it had 146,000 miles, Third owner. The second owner bought it when it had 84,000 miles. The first owner leased it. But anyways, the belt was changed at 120,000 miles by the second owner. Now, I don't know if it broke or not, the owner was a real estate agent so she did a lot of traveling, and she wasn't broke neither. lol. So, I guess it is possible to get to 125,000 or even more.

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Not replacing it electively ain't worth it!!! You know it will fail at the worst possible time under the worst possible conditions (one of Murphy's Laws) and if more than one thing goes bad, they will go bad in the worst possible sequence and combination. I'm sure there is a +50% built in durability factor, but why gamble?

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The timing belt on my the 90 LS I had was damaged (I don't remember it actually breaking) at about 80,000 miles when the water pump seized. I always replaced the belt (and related parts and the water pump) per the maintenance schedule to avoid the hassle of having it fail on a long trip.

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Water pump? Lexus uses oil cooling for the engine, not water...

ThunderRiver,

Lexus and most modern engines - now even Porsche's flat 6 opposed - are water cooled. The oil provides lubrication of moving parts.

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Well actually you are both correct. Both the oil and the coolant provide cooling, although the oil cools differently. Thunder may be thinking about old V W engines that were air cooled. In my opinion air cooled engines are great for lawnmowers, generators, and pressure washers. They are terrible in cars, especially in the winter. I froze my butt off in the winter in my dads VeeDub as the only heat came off the exhaust manifold or something.

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Oil provides a cooling function in both liquid and air cooled engines. But the cooling effect is more for particular components, like bearings and pistons, than for the block, which absorbs most of the heat. Consequently, engines are either air or liquid cooled, as they do about 80% of the cooling; the oil cooling function is assumed.

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well if the belt breaks you dont have to worry about the engine (internals ) being damaged so thats one good point but well you also could be stranded some where for a while so well do what you got to do.

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Hi after speaking to a lexus fitter here in the uk,i was told by him that it will damage my engine if the belt breaks,he said a lexus cam belt is the only one to buy as its alot better belt than aftermarket belts and will last longer,he said a lexus belt is safe for 100,000 miles..

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Meaning you have an interference engine in your '91. There have been numerous threads here about what years are interference and which aren't. I'm not sure the mystery was ever solved. :unsure:

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1990LS400, Well, I know what you meant by most conventional cars rely on water cooling. But I tell ya. In my 1994 LS400, I don't see the water pump. There is no place for me to fill in water... Last time the car was in Houston for check up, they added oil, not water. My dad and I were surprised too.. but there is no water pump in my car. For the past 7 years, we never added any water either. The only water is the windshield fluid that I bought at gas station.. :huh:

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My dad and I were surprised too.. but there is no water pump in my car.

I know that you believe this, but I would advise keeping an open mind on the subject of your car's cooling system.

Perhaps go to the dealer and ask them to simply show you where the coolant resevoir is, and how to top it up. For the sake of your engine.

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1990LS400, Well, I know what you meant by most conventional cars rely on water cooling. But I tell ya. In my 1994 LS400, I don't see the water pump. There is no place for me to fill in water... Last time the car was in Houston for check up, they added oil, not water. My dad and I were surprised too.. but there is no water pump in my car. For the past 7 years, we never added any water either. The only water is the windshield fluid that I bought at gas station..  :huh:

http://www.lextreme.com/timing.htm

review this article by moderator VFM (hosted by lextreme), and you will know where the water pump is.

actually it's burried inside the front of the engine, you can't see it without disassemble engine front end. that's why water pump is usually replaced when timing belt is changed. sorta killing 2 birds with 1 stone. u don't want to pay the labor (easily 6~8-hr times $60~$80 an hour) 2nd time just to change water pump or timing belt.

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I am nearing this very expensive repain on my 91 and even though I would rather avoid it, I know it is a necessary work at 102k miles.

Here is my concern -- I searched this site and have found no comments on how to know when you need to change your belt. Is it only dependent on the amount of miles on the vehicle/belt, or is it possible to wear to the level where it needs to be replaced before a specific mileage?

thanks

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Meaning you have an interference engine in your '91. There have been numerous threads here about what years are interference and which aren't. I'm not sure the mystery was ever solved.

Which years have interference engines is not a mystery - at least not to me and the owner of the independent repair shop to which I usually take my LS. I hope that at some point a permanent link to an authoritative web page with this information can be posted on this forum.

What really is a mystery to me is how so many Lexus dealer employees are not knowledgable about their cars. This morning I took my 2000 LS to the dealer for warranty work with one of the issues being related to the day-time running lights. Two service writers were adament that my car could not have a problem with the running lights because my car does not have them. I know that one of the two service writers had been with the dealership for quite a long time. I had to show them the page in my owners manual that explains how the day-time running lights work before they would believe me. Kind of sad.

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I am nearing this very expensive repain on my 91 and even though I would rather avoid it, I know it is a necessary work at 102k miles.

Here is my concern -- I searched this site and have found no comments on how to know when you need to change your belt. Is it only dependent on the amount of miles on the vehicle/belt, or is it possible to wear to the level where it needs to be replaced before a specific mileage?

thanks

TB itself should last 120K, but to be safe, replacing it at 90K is recommended by Lex dealers nowadays.

however, seized water pump can break the TB regardless age or mileage, that's another reason why you should change water pump while replacing TB. u don't want an old water pump to break your just-replaced TB.

in fact, while you are at it, changing the pair of disbributor caps/rotors is not a bad idea either since they need to be apart in the process of changing TB

according to local Lex dealers here, GEN 1/2 IUZFE engines in LS4/SC4 are non-interference engine, meaning no bent-valves if TB breaks.

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While we're on this topic, I'm getting ready to do mine. What parts should I replace? I know the actual belt of course :D and the water pump. Which other parts? Money is of course always a factor so I'm having my brother-in-law help me. Also, where's the cheapest place to get OEM parts? Must the water pump be OEM as well?

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http://www.lextreme.com/timing.htm

lextreme page does have the part list at the begining of article by moderator VFM.

rotors/caps/wires/plugs are really optional, but you may choose to do them at the same since all of them need to be unpluged or disassembled in the process.

in fact, I would recommend to change out the thermastat and it's gasket too. thermastat is cheap, and it will cost a lot of time or labor to replace it alone.

also, remember to go to toyata dealer to get two gallons of long-life red OAT coolant and two gallons of dis-stilled water for 1:1 mixture. essentially a coolant flush-n-refill job is part of whole 9-yards too!

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