Timing belt

Tiny
ALLANADAMS2
  • MEMBER
  • 1995 LEXUS SC 400
  • 109,000 MILES
The timimg belt was changed at 80,000 miles in 2003. Now the car has 109,000 miles, after 10 years and 30,000 miles. The car has always been well maintained by Lexus, stays outside in Austin TX, and is in excellent condition. Lexus says the belt should be changed every 10 years and wants $1300. We experct to use it for several years at 3k miles a year. How long can we continue to drive it without danger? Does the belt break suddenly or can you tell it is going before the engine is damaged? Thank you, Allan Adams
Saturday, April 27th, 2013 AT 8:58 PM

4 Replies

Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
The reason that they say a time or mileage is becausetthe belts dry rot and will break without warning. Whats your zip code so I can get you a fair price in your area.
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Saturday, April 27th, 2013 AT 9:22 PM
Tiny
ALLANADAMS2
  • MEMBER
  • 2 POSTS
Thanks saturntech9. ZIP is 78750. The car is outside mostly in shade, used about 400 miles/month in town, sometimes sits a month with no use. Carefully driven by my wife mostly, me some. I keep the maintenance current at Lexus. Allan
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Saturday, April 27th, 2013 AT 9:40 PM
Tiny
CARADIODOC
  • MECHANIC
  • 33,752 POSTS
I wouldn't panic over the age. The mileage is more important. They're worried about dry rot but belts rarely break from that.

There's two things that can happen. The belt can break, and that would be catastrophic. Your engine is an "interference" engine design which means the open valves will be hit and bent by the pistons as they coast to a stop. That requires a valve job which can be fairly expensive. The belt could also become worn and jump a tooth or two on the sprocket. That will cause low power and sluggish acceleration but no other serious damage. On some cars the Engine Computer will detect that and shut the engine down to protect the valves.

Another potential cause of timing belt failure is a worn water pump. Its pulley is one of the idler pulleys for the timing belt on your engine. All conscientious mechanics will replace the water pump and any other tensioning devices for added insurance of a reliable repair when they replace the timing belt. One thing you can do to lower the risk of the water pump failing is to replace the engine coolant every two years as all manufacturers recommend. It is normal for acids to build up in the coolant due to the normal seepage of combustion gases into the cooling system. Antifreeze has water pump lubricant and corrosion inhibitors to address that but those additives wear out in about two years regardless of how many miles that involves.
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Saturday, April 27th, 2013 AT 10:01 PM
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
I see 336-438 for just the timing belt replacement. But to do a timing belt kit water pump belt pulleys tenisor etc would be more money for parts and labor. Belts can dry rot and break. You could always pull back the upper timing belt cover to have a look at the belt.
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Sunday, April 28th, 2013 AT 6:39 PM

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