timing belt?

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Old 10 Jun 2006, 12:30 pm   #1 (permalink)
J.Lef
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Default timing belt?

My son purchased a 1990 toyota camry a few years back with about 120,000
miles on it. Its the inline 4 sedan.
He know has about 180,000 miles on it, and the vehicles gas mileage has
dropped down from about 23 miles per gallon, to about 15 miles per gallon,
about 70 percent heavy urban driving.
Also, at the advice of some people on this group, he switched to hi
test gas, because of a lot of knocking on acceleration. The hi test cured
it.
The mechanic we used, suggested changing out the timing belt. We have
not done this yet on this car, and have no idea, when and if it was done
before we got it over 60,000 miles ago, but we assume the car was well
maintained, because it was almost pristine when we got it, from an elderly
lady, who commuted to work with it from new hampshire, and had her car work
all done by the dealership as called for.
The seats even lacked brand new.
So any recommendations if the timing belt could be the cause of it, and
if not, should it be changed at this point anyway. The car runs just fine,
just getting lousy gas mileage, have to use hi test, and its pep has gone
away, but that could be of old age also. LOL

Thanks



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Old 10 Jun 2006, 01:50 pm   #2 (permalink)
m Ransley
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Default Re: timing belt?

With that many miles change the belt, I dought anybody here recomended
high octane when your issue is simply timing. But with a lack of power
you really need some work done to it, if compression is good you should
never get less than 20-24

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Old 10 Jun 2006, 02:52 pm   #3 (permalink)
johngdole@hotmail.com
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Default Re: timing belt?

Was the mileage drop gradual?

Timing belt, cam, crank, oil pump seals, water pump and drive belts
should be changed every 60K miles (although a few might strech the
pulleys and pump to 120K miles, I wouldn't). Timing belt stretches some
and retards spark timing and leads to poor performance, but not sure
about causing the engine to knock. Does it knock at highway speeds or
low speeds only?

There could be other reasons for the drop in MPG. Have the spark plugs
been replaced at all? I'd use NGK's Iridium IX BCPR5EIX-11 or at least
the cheaper NGK G-Power Platinum BCPR5EGP. Are the plug wires in good
shape? Is the oxygen sensor still good? Is the EGR system working
properly? Was the fuel filter ever changed? Is there a vacuum leak
(check PCV grommet and valve cover gasket)? Is the engine using oil?

How's the temperature gauge doing? Is it flucturating as the load
increases/decreases? I hope it's not the head gasket.


J.Lef wrote:
> My son purchased a 1990 toyota camry a few years back with about 120,000
> miles on it. Its the inline 4 sedan.
> He know has about 180,000 miles on it, and the vehicles gas mileage has
> dropped down from about 23 miles per gallon, to about 15 miles per gallon,
> about 70 percent heavy urban driving.
> Also, at the advice of some people on this group, he switched to hi
> test gas, because of a lot of knocking on acceleration. The hi test cured
> it.
> The mechanic we used, suggested changing out the timing belt. We have
> not done this yet on this car, and have no idea, when and if it was done
> before we got it over 60,000 miles ago, but we assume the car was well
> maintained, because it was almost pristine when we got it, from an elderly
> lady, who commuted to work with it from new hampshire, and had her car work
> all done by the dealership as called for.
> The seats even lacked brand new.
> So any recommendations if the timing belt could be the cause of it, and
> if not, should it be changed at this point anyway. The car runs just fine,
> just getting lousy gas mileage, have to use hi test, and its pep has gone
> away, but that could be of old age also. LOL
>
> Thanks


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Old 10 Jun 2006, 03:21 pm   #4 (permalink)
Jason James
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Default Re: timing belt?


"J.Lef" <j.lef@verizon.net> wrote in message
news:nlDig.2882$891.1296@trndny01...
> My son purchased a 1990 toyota camry a few years back with about 120,000
> miles on it. Its the inline 4 sedan.
> He know has about 180,000 miles on it, and the vehicles gas mileage has
> dropped down from about 23 miles per gallon, to about 15 miles per gallon,
> about 70 percent heavy urban driving.
> Also, at the advice of some people on this group, he switched to hi
> test gas, because of a lot of knocking on acceleration. The hi test cured
> it.


The knocking or pre-ignition noise and the drop in mileage if they are
connected, could be due to too far advanced ignition which has moved outside
the engine management's ability to correct. Why that has happened could
include belt stretching. On the otherhand, engines which have a build-up of
carbon in their combustion chambers, can suffer "engine knock". In that case
the engine would be consuming oil.

Jason


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Old 10 Jun 2006, 03:47 pm   #5 (permalink)
J.Lef
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Default Re: timing belt?

....
> Was the mileage drop gradual?


Yes. Over the space of about two years the mileage started
dropping, and acelleration diminished, even though it is still peppy, not
what it used to be.
I had a complete tuneup on it, and change my filters and oil on a
timely basis. The car usually does not need any oil, between changes(every
four thousand miles), sometimes maybee I have to add one. The knocking was
only occurring on brisk acellerations. If I got off the pedal a little and
took it easy, the knocking would stop. It would happen going away from a
stoplight if I needed to move, or getting on a freeway, or accellerating to
the passing lane. My son drives the car moderately, so it is not abused.
Upon switching to premium, 95 pecent of the knocking stops, so thats
what we have been using for the past two years. The temp gauge, stays rock
solid where it always has been, and barely moves once up to temp. This is a
great running car, and my son was thinking about throwing a new set of tires
on for another 30,000 miles of driving, but is unsure now, because of the
gas mpg problem. It hardly useds any prestone either.
What do you think I should ask our mechanic to do?

Thanks to all that have responded
>
> Timing belt, cam, crank, oil pump seals, water pump and drive belts
> should be changed every 60K miles (although a few might strech the
> pulleys and pump to 120K miles, I wouldn't). Timing belt stretches some
> and retards spark timing and leads to poor performance, but not sure
> about causing the engine to knock. Does it knock at highway speeds or
> low speeds only?
>
> There could be other reasons for the drop in MPG. Have the spark plugs
> been replaced at all? I'd use NGK's Iridium IX BCPR5EIX-11 or at least
> the cheaper NGK G-Power Platinum BCPR5EGP. Are the plug wires in good
> shape? Is the oxygen sensor still good? Is the EGR system working
> properly? Was the fuel filter ever changed? Is there a vacuum leak
> (check PCV grommet and valve cover gasket)? Is the engine using oil?
>
> How's the temperature gauge doing? Is it flucturating as the load
> increases/decreases? I hope it's not the head gasket.
>
>
> J.Lef wrote:
>> My son purchased a 1990 toyota camry a few years back with about 120,000
>> miles on it. Its the inline 4 sedan.
>> He know has about 180,000 miles on it, and the vehicles gas mileage has
>> dropped down from about 23 miles per gallon, to about 15 miles per
>> gallon,
>> about 70 percent heavy urban driving.
>> Also, at the advice of some people on this group, he switched to
>> hi
>> test gas, because of a lot of knocking on acceleration. The hi test cured
>> it.
>> The mechanic we used, suggested changing out the timing belt. We have
>> not done this yet on this car, and have no idea, when and if it was done
>> before we got it over 60,000 miles ago, but we assume the car was well
>> maintained, because it was almost pristine when we got it, from an
>> elderly
>> lady, who commuted to work with it from new hampshire, and had her car
>> work
>> all done by the dealership as called for.
>> The seats even lacked brand new.
>> So any recommendations if the timing belt could be the cause of it,
>> and
>> if not, should it be changed at this point anyway. The car runs just
>> fine,
>> just getting lousy gas mileage, have to use hi test, and its pep has gone
>> away, but that could be of old age also. LOL
>>
>> Thanks

>



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Old 10 Jun 2006, 04:41 pm   #6 (permalink)
johngdole@hotmail.com
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Default Re: timing belt?

Sounds like there may be a combination of two different things here.

The reduced performance and mileage is likley because of the aged,
streched timing belt retarding timing. Be prepared to change the oil
seals, water pump, pulleys at the same time at increased cost. I'd
prefer Gates Timing Kit and drive belts
(http://www.gates.com/index.cfm?location_id=540) and would stay away
from the Bando belts they now sell at the dealer. Do use Toyota coolant
and only distilled water if needed.

My two cents on the knocking part may be (1) mixture lean: false air
entry, low fuel pressure (actaully lots of causes of lean mixture); (2)
insufficient EGR flow: manifests under moderate acceleration but should
not pose as much of a problem moving from standing still as you
experienced.

The throttle body ports controlling the EGR system can be partially
blocked. I helped one guy clear it up after he cleaned the throttle
body and the ports got plugged up and then the engine knocked on
acceleration. Also, replacing the fuel filter can help rid the
start-up knocking in a 5S-FE. The lower flare nut can be a bear to
remove and the filter is supposed to be lifetime. Was your fuel filter
ever replaced? Iridium plugs that can burn leaner mixtures can also
help. But I am not sure if yours is the same problem, maybe others can
chime in.

It's probably not interal oil leaks (piston rings or valve stems)
because you are not using oil. Is there blue smoke on cold starts? Oil
reduces the octane count and contributes to detonation.


J.Lef wrote:
> ...
> > Was the mileage drop gradual?

>
> Yes. Over the space of about two years the mileage started
> dropping, and acelleration diminished, even though it is still peppy, not
> what it used to be.
> I had a complete tuneup on it, and change my filters and oil on a
> timely basis. The car usually does not need any oil, between changes(every
> four thousand miles), sometimes maybee I have to add one. The knocking was
> only occurring on brisk acellerations. If I got off the pedal a little and
> took it easy, the knocking would stop. It would happen going away from a
> stoplight if I needed to move, or getting on a freeway, or accellerating to
> the passing lane. My son drives the car moderately, so it is not abused.
> Upon switching to premium, 95 pecent of the knocking stops, so thats
> what we have been using for the past two years. The temp gauge, stays rock
> solid where it always has been, and barely moves once up to temp. This is a
> great running car, and my son was thinking about throwing a new set of tires
> on for another 30,000 miles of driving, but is unsure now, because of the
> gas mpg problem. It hardly useds any prestone either.
> What do you think I should ask our mechanic to do?
>


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Old 10 Jun 2006, 04:43 pm   #7 (permalink)
m Ransley
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Default Re: timing belt?

A good mech knows what to do, check everything. But knocking nornaly is
the timing is to advanced or pre-ignition, the fuel is igniting well
before the piston reaches top center, although to far advanced you loose
power. the oposite is a stretched belt, it retards timing and reduces
power economy. It could be set to advanced, you can buy a 15$ timing
light and see yourself, there are 2 wires to jump T & E1 on the terminal
block, if you want to do it yourself its a easy 5 minute job. But lack
of power-milage, look at a blocked Cat converter, bad o2 sensor. draging
brakes or bearings. Have you ever checked or changed the differential
oil, it is seperate from the trans and can only be done from a lift with
special wrench. There is also an engine knock sensor, but first try a
timing light, fix the knock it might be your whole issue. One idea go
see if the distributor was left loose, go and try to turn it, a mechanic
might have forgot, this could be your whole problem.

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Old 10 Jun 2006, 07:14 pm   #8 (permalink)
m Ransley
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Default Re: timing belt?

He said high octane stopped the knock, so its pre ignition, not a lean
mix, its timing related.

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Old 10 Jun 2006, 09:37 pm   #9 (permalink)
Daniel
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Default Re: timing belt?

J.Lef wrote:
> My son purchased a 1990 toyota camry a few years back with about 120,000
> miles on it. Its the inline 4 sedan.
> He know has about 180,000 miles on it, and the vehicles gas mileage has
> dropped down from about 23 miles per gallon, to about 15 miles per gallon,
> about 70 percent heavy urban driving.
> Also, at the advice of some people on this group, he switched to hi
> test gas, because of a lot of knocking on acceleration. The hi test cured
> it.

---
> So any recommendations if the timing belt could be the cause of it, and
> if not, should it be changed at this point anyway. The car runs just fine,
> just getting lousy gas mileage, have to use hi test, and its pep has gone
> away, but that could be of old age also. LOL

===========================================
First check the spark plug wire resistance. If those are original
wires, they're likely due for a change. Plugs would be due at this
point also. Use what is recommended in the owner's manual, most likely
ND platinum. To avoid problems use only Toyota spark plug wires.
That engine does not require premium fuel so something else is going
on.
The timing belt is fiberglass reinforced and the fiberglass strands
should not stretch, but with flexing over time they can break, so it is
prudent to change the timing belt.
If the EGR port (vacuum modulator or exhaust gas) is blocked, that
would explain the knocking on acceleration.
If the oxygen sensor is not responding properly that would explain the
low mileage.
The O2 sensor can be tested with a voltmeter, should be not less than 8
swings of the needle in 10 seconds.
The EGR valve exhaust gas flow can be tested by applying a vacuum at
idle to see if the engine dies when the exhaust is introduced, if not,
the port is blocked.
BTW, Prestone has a tendency to slowly destroy the cooling ability of
your radiator. Use Toyota red with distilled water if you want to
maintain it correctly and avoid build up of insulating deposits in the
radiator core and water jacket.
Also, allowing the car's state of tune to deteriorate can be
cumulative. For example, when the mileage goes down and is left
uncorrected, the hydrocarbons don't burn completely, resulting in
greater accumulation on the oxygen sensor which causes it to "become
lazy" that is respond more slowly worsening fuel economy further, and
also can put a larger burden on the catalytic converter causing that
rather expensive part to run hotter and fail sooner.

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Old 11 Jun 2006, 01:27 am   #10 (permalink)
johngdole@hotmail.com
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Default Re: timing belt?

Octane is the anti-knock index. Higher octane gas can better resist
detonation. But an engine that calls for regular gas should be running
on regular gas. High octane gas is just a temporary fix. Lean mixture,
as well as advanced timing, can lead to increased combustion
temperatures and detonation.

Preignition is caused by excessively hot cylinder components, a
condition unlike detonation, exists typically in only a small number of
cylinders. Hot valves, carbon particles, or even a spark plug not able
to properly dissipate heat can be the causes.


m Ransley wrote:
> He said high octane stopped the knock, so its pre ignition, not a lean
> mix, its timing related.


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