But a local mechanic told me that the sprockets / gears are equally important to replace.
Of course, local mechanics say a lot of things.
Is he correct?
I paid $180 for the chain and would prefer not to have to pay that much more for more parts so I'm hoping that someone will tell me that the gears rarely fail.
The thing with timing chains is that over time they stretch. The links wear down since they are constantly pivoting with respect to each other. The teeth on the gears wear down with the chain, making the distance between teeth longer. If one replaces only the chain, it will not mesh very well with the worn teeth. Pretty soon the new chain will be stretched to match the teeth, just like the old one was.
I do not have a first hand experience with the engine that sits in your car though, so I do not know how likely these components need replacement after your mileage. The description above is based on what happens after 170k miles to many '92-93-ish SAAB 9000. Which by the way is a real POS setup as you pretty much have to take out the engine to replace all the hardware associated with the chain (tensioner, sprockets, guides and whatnot).
Haynes manual for the Corolla lists a couple of specs to determine whether or not chain and sprockets are due for replacement.
Maximum chain length at 16 pins (see text)................................... 122.7 mm
Crankshaft sprocket minimum diameter (with chain)......................... 51.6 mm
Camshaft sprocket minimum diameter (with chain).......................... 97.3 mm
Inspection
Pull the timing chain taut by hand, and measure the length of 16 pins. Repeat this procedure at 3 or more sections of the chain. If any of the measurements obtained exceed that given in the Specifications, the chain must be renewed.
Wrap the chain around the crankshaft sprocket and use a pair of vernier calipers to measure the diameter of the assembly. If the measurement obtained is less than that given in the Specifications, renew the chain and all the sprockets. Repeat this procedure on both camshaft sprockets.
Check the condition of the chain guide and tensioner slipper. There should be no sign of cracking or damage. As the chain runs along the guide/slipper it will create two grooves along the slipper/guide length. The maximum depth of these grooves is 1.0 mm. If their depth exceeds this, renew the slipper/guide.
Since I can't do the work myself, I have to have a mechanic do it, and I need my car back the same day - he lives near my job so he picks it up and returns it before 5 PM. So if he tears it apart and measures it and finds that it needs sprockets, he has to put it all back together so I have my car back for a day or two while the parts come in.
I could just have local dealership do it for $500 or whatever they would charge but that's a rather large fraction of what the car is worth with 210 thousand on it!
There's something to be said for owning a newer car - trying to save a buck is a PITA! : - )
I really need to learn to do this stuff myself, this is just painful. : - )
Last edited by StephanieD; 08-30-2011 at 08:13 PM.
There's something to be said for owning a newer car - trying to save a buck is a PITA! : - )
I really need to learn to do this stuff myself, this is just painful. : - )
Newer cars have their problems too. It is true that you'll save money doing the work yourself but there is an investment in time , tools and knowledge acquisition. Many of the new cars make it almost impossible to DIY service anymore.
Replacing a timing chain is doable but may be a bit difficult for you. Getting at all the bolts etc. isn't particularly pleasant especially if you don't have a garage. Assuming you have the necessary tools, you certainly should be able to do it during a weekend.
I don't know about the Corollas, but in most cars with a timing chain if it gets noisy then it is time to replace it.
Can anyone confirm that the 1ZZFE is an interference engine? Meaning that the engine can destroy itself internally if the chain breaks.
Unless there was a known problem with the chain ,I would leave it alone. Can you return the chain?
Yes the sprockets wear with the chain. Will the engine self destruct or run badly by just changing the chain and not the gears ... unless the gears are damaged or extremely worn, no. Why are you changing the chain?
After some research, you're correct. 1998 and later, it is interference engine.
So, the Interference and Non Interference engine is depended on the year it was built.
I have a friend who owns a Corolla, I don't know which year. He let a car dealer changed the timing belt, he was in L. A. coming back to the Bay Area. Half way, the timing belt came off, he did not sustain an engine damage. He had the car towed and redone the timing belt. Later the dealer that did the timing belt agreed to pay half the cost of his repair. So, if you're lucky depends on the circumstances and who was working on your car. In any rate, that is just one incident that I recalled.
Take care!
Last edited by Beekeeper2020; 01-08-2012 at 01:08 AM.
Reason: Edit for clearification
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