New here with question
01-27-12, 05:27 PM
#16
Recovering Lexus Addict
The LS has an interference engine, meaning that the pistons and valves occupy the same space in the cylinder at different times during the cycle. If the timing belt breaks, pistons and valves will meet with expensive results. In a non-interference engine, a broken timing belt simply means coasting to a stop with no permanent damage.
01-27-12, 08:44 PM
#17
Moderator
Caddy is 100% correct. On the LS the TB acts to open and close the overhead valves that intrude into the combustion chamber when they are open. When the TB breaks some of the valves remain in the open position and get slammed by the piston heads coming up during the compression stroke. Result is some badly bent and/or broken valves, in addition to some holes and/or significant damage to the pistons. In short the top end of your motor is usually trashed in just a few seconds when the TB breaks. Something to seriously be avoided as it will likely ruin your whole day.
There is anecdotal evidence that the Lexus 90k TB replace recommendation on the LS430 motor is pretty conservative so its very likely that folks could delay it a bit and get away with it. But if you think about it pragmatically it doesn't make a lot of sense to wait for most people if they are keeping the car - it really should be done relatively soon after 90k so why push it and take a risk if you are gonna keep the car?
However if I was selling my LS with 90-100k on it and the TB had not been done, I'd sell it without doing the TB and give some discount to the buyer and let them worry about it. The discount to sell is likely smaller then the actual full maint bill for replacing TB and WP. Buyers are usually unrealistically optimistic about what a repair or Maint bill will actually cost.
There is anecdotal evidence that the Lexus 90k TB replace recommendation on the LS430 motor is pretty conservative so its very likely that folks could delay it a bit and get away with it. But if you think about it pragmatically it doesn't make a lot of sense to wait for most people if they are keeping the car - it really should be done relatively soon after 90k so why push it and take a risk if you are gonna keep the car?
However if I was selling my LS with 90-100k on it and the TB had not been done, I'd sell it without doing the TB and give some discount to the buyer and let them worry about it. The discount to sell is likely smaller then the actual full maint bill for replacing TB and WP. Buyers are usually unrealistically optimistic about what a repair or Maint bill will actually cost.
Last edited by Jabberwock; 01-27-12 at 08:49 PM.
01-28-12, 06:54 PM
#18
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In my opinion the T-belt is not something to go and push replacing as I have seen them break at 85k miles and I have also worked on cars with 180k and the original T-belt and still running. If the dealer is through the roof expensive I would recommend what most others are and get all the OEM parts and have an indy put them on for ya.
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