Does anyone know with absolute certainty if a timing belt breaks on a 2000 LX 470 , will engine damage result??? My dealer says no. This forum has had other opinions. Speak the truth oh mighty Lexus sage!!!

 

yes it will

 

i heard it can almost burn out your engine, but then again, thats what i haerd

 

does your engine have a VVT-i badge? If so, a broken timing belt could be catastrophic, due to the fact that it's an "interference engine"--meaning pistons and valves will come crashing together.

 

Can you get that dealer to put it in writing? Get the service manager to sign off on that doccument? Change the timing belt and water pump every 90K miles then you don't have to ask this question.

 

A timing belt failure on any interferance motor (all variable valve timing motors are interferance motors, as well as pretty much any DOHC design or multivalve design) will result in bent valves and usually at that point it's cheaper, easier, and more reliable to just replace the entire motor. So yes, a timing belt failure as minor as it may seem is just about the worst failure you can have. Even on non-interferance motors your engine will probably not work nearly as well as it did before the failure.

Makes me mad that they don't use timing chains instead of belts. Timing chains last forever, or for some that are really paranoid they get changed every 200k miles, but that's still paranoid. Why doesn't lexus use them? Because they make the motor a little noisier (marginally at best).

Waterpump is not routine maintinance unless you just want to save on labor by combining the cost of the two. Ideally a water pump will last forever or at least for 150k-200k miles or so. GM doesn't consider it a routine maintinance item, I don't know why Lexus would.

And unlike a timing belt, if a water pump fails it's not going to destroy your motor instantly.

 

To me, timing belt and water pump are preventive maintenance. Do you want to pay someone again or even if you DIY to go back in and replace the water pump IF it fail on you???

 

tantheman,
Like VQT said, just change your t-belt and water pump @90k miles. Even if a broken t-belt doesn't bend any valves, it most probably will leave you stranded. It WILL break sooner or later, why not change it out at 90k for peace of mind?

Threxx,
Timing chains do NOT last forever. They stretch, making your cam timing and distributor timing off, losing engine power. Longer chains are even more susceptible to this. Look at any R series toyota engine 18R, 20R, 22RE etc etc. These engines usually have severe timing chain stretch by 100k miles. The shorter chains in american V8 last a bit longer, 150k miles or so. True they won't leave you stranded like a broken t-belt will but for optimal performance they should still be considered a maintanence item.

The water pump should be considered a PREVENTIVE Maintanence item. It might last 150k miles it might even last 200k miles, but what happens when it goes bad, causes an overheat and blows your head gaskets? It's a wear item and WILL go bad, why not change it ...again for peace of mind.

I prefer a belt over a chain, they are less expensive to buy last about the same and are much easier to change and much less noisy. They can also rev to 9000rpm ( of course the 1UZ can't but the belt can ). Anything over 7000rpm in american V8 use gears, not chains.

Regards

 

When I changed my timing belt the first time, it was at 153k miles... I got the car at 143k and didnt occur to me that the belt needed changing.. The mechanic said the tensior was soo bad that he could litteraly move the belt around

 

Timing chains aren't foolproof--especially not their tensioners. I remember reading in this forum about the guy whose chain tensioner failed on his 93 Q45, dropping the chain and ruining the engine.

 

Timing chains are the thing of the past and they do break with catastrophic results. Timing belts aren't that difficult to change and offer many benefits. Timing belt breakage on non-interference engines will NOT harm the engines in ANYWAY after a proper belt replacement.

 

[QUOTE]Originally posted by Threxx
[B]A timing belt failure on any interferance motor (all variable valve timing motors are interferance motors, as well as pretty much any DOHC design or multivalve design) will result in bent valves and usually at that point it's cheaper, easier, and more reliable to just replace the entire motor. So yes, a timing belt failure as minor as it may seem is just about the worst failure you can have. Even on non-interferance motors your engine will probably not work nearly as well as it did before the failure.

Makes me mad that they don't use timing chains instead of belts. Timing chains last forever, or for some that are really paranoid they get changed every 200k miles, but that's still paranoid. Why doesn't lexus use them? Because they make the motor a little noisier (marginally at best).



Because the belt is much more accurate for timing.........and thats what LEXUS is about.