Cold start noise

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Old 18 May 2005, 09:50 pm   #1 (permalink)
freelait2000@yahoo.com
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Default Cold start noise

Hi,
My car is a Camry 90'(4 cylinder, automatic trans, 110k miles). Two
months ago, it began develop a noise when cold start, especially in
morning. The engine sounds no more smooth. After driving several miles,
I cannot hear it anymore. The noise is a little like metal strike,
although it is absolutely not sharp. All and all, I cannot describe it
more clearly. I once drove the car to a garage one hour earlier in
order the car was cool enough and the technician could hear the noise.
But the noise was not obvious then. The technician could not find
anything wrong. For me, I feel the engine does not sound smooth than
two month ago even when the car is hot now. The technician didn't think
there was problem though.

The timing belt was not changed before. From the newsgroup it seemed
that worn timing belt may cause this. Unfortunately after changing
timing belt and water pump, the noise is still there.
Somebody in this newsgroup mentioned knocking sensor to cold start
noise. Although I have the Haynes repair manual, I cannot find the
sensor. If there is a knocking sensor for 3SFE engine, where is it?

What can I check for the noise?


Thank you very much.

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Old 19 May 2005, 12:43 am   #2 (permalink)
Jason James
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Default Re: Cold start noise


<freelait2000@yahoo.com> wrote in message
news:1116471037.933159.143320@z14g2000cwz.googlegr oups.com...
> Hi,
> My car is a Camry 90'(4 cylinder, automatic trans, 110k miles). Two
> months ago, it began develop a noise when cold start, especially in
> morning. The engine sounds no more smooth. After driving several miles,
> I cannot hear it anymore. The noise is a little like metal strike,
> although it is absolutely not sharp. All and all, I cannot describe it
> more clearly. I once drove the car to a garage one hour earlier in
> order the car was cool enough and the technician could hear the noise.
> But the noise was not obvious then. The technician could not find
> anything wrong. For me, I feel the engine does not sound smooth than
> two month ago even when the car is hot now. The technician didn't think
> there was problem though.
>
> The timing belt was not changed before. From the newsgroup it seemed
> that worn timing belt may cause this. Unfortunately after changing
> timing belt and water pump, the noise is still there.
> Somebody in this newsgroup mentioned knocking sensor to cold start
> noise. Although I have the Haynes repair manual, I cannot find the
> sensor. If there is a knocking sensor for 3SFE engine, where is it?
>
> What can I check for the noise?
>
>
> Thank you very much.


Could be piston-slap,..this can occur after high miles without proper
oil-change maintenance or thru an overheat with a scuffed piston,..or just
thru a grade piston which was a bit too loose at the factory build.

Typically the noisy piston makes a hollow light tapping noise which gets
louder you drive off and load on the engine increases,..after about 10
minutes most moderate slappy pistons go quiet as the bore to piston
clearance reduces as the piston heats up.

Jason



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Old 26 May 2005, 01:41 pm   #3 (permalink)
freelait2000@yahoo.com
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Default Re: Cold start noise


>
> Could be piston-slap,..this can occur after high miles without proper
> oil-change maintenance or thru an overheat with a scuffed piston,..or just
> thru a grade piston which was a bit too loose at the factory build.
>
> Typically the noisy piston makes a hollow light tapping noise which gets
> louder you drive off and load on the engine increases,..after about 10
> minutes most moderate slappy pistons go quiet as the bore to piston
> clearance reduces as the piston heats up.
>
> Jason


What is the consequence of piston-slap? Could you tell me?


Thanks,

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Old 28 May 2005, 08:15 pm   #4 (permalink)
Jason James
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Default Re: Cold start noise


<freelait2000@yahoo.com> wrote in message
news:1117132864.835165.316910@g49g2000cwa.googlegr oups.com...
>
> >
> > Could be piston-slap,..this can occur after high miles without proper
> > oil-change maintenance or thru an overheat with a scuffed piston,..or

just
> > thru a grade piston which was a bit too loose at the factory build.
> >
> > Typically the noisy piston makes a hollow light tapping noise which gets
> > louder you drive off and load on the engine increases,..after about 10
> > minutes most moderate slappy pistons go quiet as the bore to piston
> > clearance reduces as the piston heats up.
> >
> > Jason

>
> What is the consequence of piston-slap? Could you tell me?
>
>
> Thanks,


None that would worry you for many years. Noisey pistons (for what-ever
reason) are a fact of life in some race engines when they are cold,...in
fact engine manufacturers of performance engines in 'muscle cars' have long
resigned themselves to the fact that the customer just wont accept piston
slap while the engine heats up. It effectively limits the optimum design
piston for turbo/supercharged engines which have higher piston-crown
temperatures.

Jason


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