From: Jeff Strickland on

"Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message
news:z8qdnZTUK4aKm_fanZ2dnUVZ_tGonZ2d(a)comcast.com...
>
> "Jeff Strickland" <crwlr(a)verizon.net> wrote in message
> news:Y8faj.28686$JW4.9295(a)trnddc05...
>>I have to take issue with the comment.
>>
>> I can't say if the motor is a non-interference type or not, but the
>> determining factor is not the presence of a timing belt. That is, simply
>> using a belt as opposed to a chain does not prescribe interference or
>> non-interference. It's possible that Toyota makes such a distinction, but
>> this is not the determining factor in the grand scheme of things.
>>
>> Interference, or the lack of it, describes the ability of the pistons and
>> valves to collide should something go astray. Interference is more
>> accurately denoted by the compression ratio -- a low ratio will have more
>> room in the combustion chamber for the piston and valve to peacefully
>> co-exist.
>>
>> I have to wonder at the response you received because I do not expect the
>> ability for the pistons and valves to collide to be related to the kind
>> of valve timing mechanism. I suspect the motor is the non-interference
>> type, but not because it uses a timing belt as opposed to a timing chain.
>>
>
> The service coordinator provided the correct answer (that the 1MZ-FE
> engine is non-interference) but provided the incorrect reasoning for the
> answer. It used to be that Toyotas with timing belts were all
> non-interference, and Toyotas with Timing chains were interference, but
> that is no longer always the case.
>
>


Really! That's interesting. I was not aware that the distinction of a belt
or a chain translated through to the ability of the pistons and valves to
run into one another. It makes sense because logic says a chain is stronger
so it would be used where there could be a problem if it broke, and a belt
would be used in applications where it wouldn't matter to the valves if it
broke. But, we have all heard of belted motors that bend valve stems because
the belt broke.

I thought the decision of belts vs. chains was driven by reasons other than
whether the pistons would run into the valves, among those reasons being
weight and cost. Lower weight would lead to less inertia, and therefore
quicker revving. Belts ought to be cheaper too.






From: Ray O on

"Keith Lee" <cmarvel(a)NOSPAM.nethere.com> wrote in message
news:pan.2007.12.20.12.59.46(a)NOSPAM.nethere.com...
> On Wed, 19 Dec 2007 23:53:29 -0600, Ray O wrote:
>> The service coordinator provided the correct answer (that the 1MZ-FE
>> engine is non-interference) but provided the incorrect reasoning for the
>> answer. It used to be that Toyotas with timing belts were all
>> non-interference, and Toyotas with Timing chains were interference, but
>> that is no longer always the case.
>
> Ray:
> How do you know it is non-interference? I have seen some websites say yes
> and some say no. I have talked
> to some former auto technical people who say it isn't. Just curious about
> your info. Thanks!
>
> Keith

Good question! I don't remember where I heard that tidbit, (I think it was
from one of the Toyota Master techs who used to frequent this group) and
since it is the same engine in our Avalon, I retained it. That said, I
don't recommend waiting to find out whether I am correct or not! ;-)
--

Ray O
(correct punctuation to reply)


From: Ray O on

"mrsteveo" <mrsteveo(a)gmail.com> wrote in message
news:f92c8b47-0814-42f8-abfe-8be0792fb87b(a)s12g2000prg.googlegroups.com...
> On Dec 20, 5:00 am, Keith Lee <cmar...(a)NOSPAM.nethere.com> wrote:
>> On Wed, 19 Dec 2007 23:53:29 -0600, Ray O wrote:
>> > The service coordinator provided the correct answer (that the 1MZ-FE
>> > engine is non-interference) but provided the incorrect reasoning for
>> > the
>> > answer. It used to be that Toyotas with timing belts were all
>> > non-interference, and Toyotas with Timing chains were interference, but
>> > that is no longer always the case.
>>
>> Ray:
>> How do you know it is non-interference? I have seen some websites say
>> yes and some say no. I have talked
>> to some former auto technical people who say it isn't. Just curious
>> about your info. Thanks!
>>
>> Keith
>
> Ray O is a former employee of Toyota who donates his time and energy
> to this newsgroup among many others.
>
> So on this note, is there a comprehensive list of Toyota's or any
> vehicles where you can find out if they're interference or not?
>
> I have a 2002 Corolla -- it's a chain -- is it interference?
>
> Thanks,
>
> Steve

I don't know whether the 2002 Corolla has an interference engine or not, but
my guess is that it has an interference engine.
--

Ray O
(correct punctuation to reply)


From: Ray O on

"Jeff Strickland" <crwlr(a)verizon.net> wrote in message
news:XHzaj.39080$ZA4.12688(a)trnddc03...
>
<snipped>
>>
>> The service coordinator provided the correct answer (that the 1MZ-FE
>> engine is non-interference) but provided the incorrect reasoning for the
>> answer. It used to be that Toyotas with timing belts were all
>> non-interference, and Toyotas with Timing chains were interference, but
>> that is no longer always the case.
>>
>>
>
>
> Really! That's interesting. I was not aware that the distinction of a belt
> or a chain translated through to the ability of the pistons and valves to
> run into one another. It makes sense because logic says a chain is
> stronger so it would be used where there could be a problem if it broke,
> and a belt would be used in applications where it wouldn't matter to the
> valves if it broke. But, we have all heard of belted motors that bend
> valve stems because the belt broke.
>
> I thought the decision of belts vs. chains was driven by reasons other
> than whether the pistons would run into the valves, among those reasons
> being weight and cost. Lower weight would lead to less inertia, and
> therefore quicker revving. Belts ought to be cheaper too.
>

The distinction of belt = non-interference and chain = interference is not
universal across automakers. For example, most Hondas have interference
engines, whether or not they have a belt. Toyota used to use make engines
with belts free-wheeling, but I don't think that is still always the case.

The two main reasons for using a belt over a chain are initial cost and
noise reduction. Advancements in chain and chain tensioning technology have
made them almost as quiet as a belt, and the cost is not that much more, so
Toyota has started to use chains more often in newer engines.

--

Ray O
(correct punctuation to reply)


From: Keith Lee on
Ray:
Oh, I agree wholeheartedly that I should not wait too long. I don't travel that much; and, I won't have the
money for my local Toyota agency to replace the timing belt until early January 2008. I think that even with 10
years use of my car by two previous owners but only 72K of mileage on the car, I should be alright until then.
Thank you for the help you and the others have given me on this matter.


Happy Holidays,
Keith Lee