Piston/Valve CLASH ?

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Steve Giannoni - 24 Apr 2008 22:30 GMT

If the timing belt slips or fails, does the piston clash with the
valves ?! ... ( Specifically : '97 Corolla and '01 Prius )

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hachiroku - 25 Apr 2008 00:24 GMT

> If the timing belt slips or fails, does the piston clash with the
> valves ?! ... ( Specifically : '97 Corolla and '01 Prius )

No. Both are DOHC engines. Toyota DOHCs are all noninterference.

Most Toyota SOHC are interference.

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Daniel Who Wants to Know - 25 Apr 2008 03:41 GMT

>> If the timing belt slips or fails, does the piston clash with the
>> valves ?! ... ( Specifically : '97 Corolla and '01 Prius )
>
> No. Both are DOHC engines. Toyota DOHCs are all noninterference.
>
> Most Toyota SOHC are interference.

And the 1NZ-FXE used in the Prius has a timing chain not a belt.

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Ray O - 25 Apr 2008 05:19 GMT

> If the timing belt slips or fails, does the piston clash with the
> valves ?! ... ( Specifically : '97 Corolla and '01 Prius )

According to Gates, the '97 Corolla has an non-interference engine, which
means that the piston will not contact the valves if the timing belt slips
or fails.

The Prius has a timing chain, and if it fails, the valves will probably
contact the pistons.

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Ray O
(correct punctuation to reply)

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Mark A - 25 Apr 2008 06:05 GMT

> According to Gates, the '97 Corolla has an non-interference engine, which
> means that the piston will not contact the valves if the timing belt slips
> or fails.

If a timing belt "slips" does the value timing go out of adjustment (even if
it does not strike the piston) or is it self-adjusting ?

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Ray O - 25 Apr 2008 06:16 GMT

>> According to Gates, the '97 Corolla has an non-interference engine, which
>> means that the piston will not contact the valves if the timing belt
>> slips or fails.
>
> If a timing belt "slips" does the value timing go out of adjustment (even
> if it does not strike the piston) or is it self-adjusting ?

Now that I think about it, the only way a Toyota timing belt would slip is
if most or all of the cogs on the belt sheared off or the tensioner failed.
If a timing belt did somehow slip, the valve timing will be incorrect and is
not self adjusting.

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Ray O
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mack - 26 Apr 2008 22:24 GMT

>>> According to Gates, the '97 Corolla has an non-interference engine,
>>> which means that the piston will not contact the valves if the timing
[quoted text clipped - 7 lines]
> failed. If a timing belt did somehow slip, the valve timing will be
> incorrect and is not self adjusting.

The belt on my '86 Camry had only one or two of the cogs slough off the
belt, and it was enough to strand the car in my driveway...and evidently it
occurred upon starting ...or trying to start.

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Ray O - 27 Apr 2008 06:58 GMT

>>>> According to Gates, the '97 Corolla has an non-interference engine,
>>>> which means that the piston will not contact the valves if the timing
[quoted text clipped - 7 lines]
>> failed. If a timing belt did somehow slip, the valve timing will be
>> incorrect and is not self adjusting.

>> (correct punctuation to reply)
> The belt on my '86 Camry had only one or two of the cogs slough off the
> belt, and it was enough to strand the car in my driveway...and evidently
> it occurred upon starting ...or trying to start.

Doh! I stand corrected. I was thinking about the crankshaft side of the
belt, but yes, since the camshaft sprocket is a much smaller diameter, the
loss of one or two cogs would strand the car.

Mack gets the prize for catching Ray's error!

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Ray O
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