Ping Ray O re: temps for 4AC?

Hi Ray O

You gave me some pointers re: overheating 4AC earlier on.

I'm still not convinced that it is overheating [1] and have been logging
temp readings. What would Toyota's max temp for the 4AC 1.6 be?[2].

Cheers

H

[1] No coolant loss, no contamination of fluids etc etc and the erratic
nature of tacho and temp gauge (not dissimilar to a volvo and VW that had
poorly connected voltage regulators on/in the circuitry of the gauge).

[2] I'm guessing 130 degrees Celsius?

On Fri, 06 Oct 2006 14:25:23 +0000, Hammo wrote:
[color=blue]
> Hi Ray O
>
> You gave me some pointers re: overheating 4AC earlier on.
>
> I'm still not convinced that it is overheating [1] and have been logging
> temp readings. What would Toyota's max temp for the 4AC 1.6 be?[2].
>
> Cheers
>
> H
>
> [1] No coolant loss, no contamination of fluids etc etc and the erratic
> nature of tacho and temp gauge (not dissimilar to a volvo and VW that had
> poorly connected voltage regulators on/in the circuitry of the gauge).
>
> [2] I'm guessing 130 degrees Celsius?[/color]


130C seems a bit high! (When you consider 100 is Boiling)
Now, are you talking COOLANT temps, or are you measuring the engine itself?

Seems to me on this engine, about 190-200 would be the max for coolant
temps (that's Degrees F, BTW)

"Hammo" <hbaj2006@aapt.net.au> wrote in message
news:C14CA46E.DA10%hbaj2006@aapt.net.au...[color=blue]
> Hi Ray O
>
> You gave me some pointers re: overheating 4AC earlier on.
>
> I'm still not convinced that it is overheating [1] and have been logging
> temp readings. What would Toyota's max temp for the 4AC 1.6 be?[2].
>
> Cheers
>
> H
>
> [1] No coolant loss, no contamination of fluids etc etc and the erratic
> nature of tacho and temp gauge (not dissimilar to a volvo and VW that had
> poorly connected voltage regulators on/in the circuitry of the gauge).[/color]

By any chance, are there any aftermarket accessories installed like fog
lights, audio system, security system, remote start, etc.? If so, check the
installation very carefully to make sure any power taps or screws are not
causing the problem.

This is not easy, but you may want to check to make sure the connectors in
the back of the instrument cluster are tight and ground connections are
tight. I believe that there is a voltage regulator on the back of the
instrument cluster, but they do not fail very often.[color=blue]
>
> [2] I'm guessing 130 degrees Celsius?
>[/color]

Without looking at the actual specifications, I can't say for sure, but I do
not think the max temp is that high. My guess would be in the 115 to 200
Celsius range.

If you can get a hold of a factory repair manual, there are voltage or
resistance specifications for temperature sender output. You can measure
the voltage at the sender and then again at the instrument cluster to see if
they are the same. The repair manual also shows how to diagnose whether the
instrument cluster is working or not.
--

Ray O
(correct punctuation to reply)

On 7/10/06 1:18 AM, in article
86393$452674d3$44a4a10d$11521@msgid.meganewsservers.com, "Ray O"
<rokigawaATtristarassociatesDOTcom> wrote:
[color=blue]
>
> "Hammo" <hbaj2006@aapt.net.au> wrote in message
> news:C14CA46E.DA10%hbaj2006@aapt.net.au...[color=green]
>> Hi Ray O
>>
>> You gave me some pointers re: overheating 4AC earlier on.
>>
>> I'm still not convinced that it is overheating [1] and have been logging
>> temp readings. What would Toyota's max temp for the 4AC 1.6 be?[2].
>>
>> Cheers
>>
>> H
>>
>> [1] No coolant loss, no contamination of fluids etc etc and the erratic
>> nature of tacho and temp gauge (not dissimilar to a volvo and VW that had
>> poorly connected voltage regulators on/in the circuitry of the gauge).[/color]
>
> By any chance, are there any aftermarket accessories installed like fog
> lights, audio system, security system, remote start, etc.? If so, check the
> installation very carefully to make sure any power taps or screws are not
> causing the problem.[/color]

There are several and I am not convinced that they haven't caused the
problem. The quickest (and hence most efficient) way to check the actual
temp was to insert a thermocouple into the coolant stream at roughly the
same point as the temp sender and compare. The only draw back of this
method is that I do not know the maximum operating temp slated for the 4AC
motor.[color=blue]
>
> This is not easy, but you may want to check to make sure the connectors in
> the back of the instrument cluster are tight and ground connections are
> tight. I believe that there is a voltage regulator on the back of the
> instrument cluster, but they do not fail very often.[/color]

True, but things fail and considering I have experienced this problem before
in other vehicles, I don't consider it outside the realms of probability.
The thermocouple shows a temp of 110 and the gauge is _above_ red, which is
just not possible (without the usual obvious signs of overheating).[color=blue][color=green]
>>
>> [2] I'm guessing 130 degrees Celsius?
>>[/color]
>
> Without looking at the actual specifications, I can't say for sure, but I do
> not think the max temp is that high. My guess would be in the 115 to 200
> Celsius range.[/color]

That is the normal op temp, or do you mean max temp that should result in
the engine being damaged?[color=blue]
>
> If you can get a hold of a factory repair manual, there are voltage or
> resistance specifications for temperature sender output. You can measure
> the voltage at the sender and then again at the instrument cluster to see if
> they are the same. The repair manual also shows how to diagnose whether the
> instrument cluster is working or not.[/color]

I have replaced the sender unit and both unit where within a small amount of
the other in terms of voltage. How this translates into temperature, I
don't have that manual with me, nor do I have with me a device to increase
the voltage to ensure I have the correct voltage is applied to the gauge.

Many thanks for your input.

Hammo

On 7/10/06 1:15 AM, in article dquVg.19$HP.18@trndny08, "Hachiroku"
<Trueno@ae86.gts> wrote:
[color=blue]
> On Fri, 06 Oct 2006 14:25:23 +0000, Hammo wrote:
>[color=green]
>> Hi Ray O
>>
>> You gave me some pointers re: overheating 4AC earlier on.
>>
>> I'm still not convinced that it is overheating [1] and have been logging
>> temp readings. What would Toyota's max temp for the 4AC 1.6 be?[2].
>>
>> Cheers
>>
>> H
>>
>> [1] No coolant loss, no contamination of fluids etc etc and the erratic
>> nature of tacho and temp gauge (not dissimilar to a volvo and VW that had
>> poorly connected voltage regulators on/in the circuitry of the gauge).
>>
>> [2] I'm guessing 130 degrees Celsius?[/color]
>
>
> 130C seems a bit high! (When you consider 100 is Boiling)[/color]

100 is only boiling when coolant is pure water and does not include
dissolved salts. Also, as the coolant is in a pressurised system, boiling
at 100 would not make any sense.
[color=blue]
> Now, are you talking COOLANT temps, or are you measuring the engine itself?[/color]

Coolant[color=blue]
>
> Seems to me on this engine, about 190-200 would be the max for coolant
> temps (that's Degrees F, BTW)[/color]

Why so low? I have a pressurised system in the 4AC.

Cheers

H

"Hammo" <hbaj2006@aapt.net.au> wrote in message
news:C14D5C37.E1D7%hbaj2006@aapt.net.au...[color=blue]
>
>
>
> On 7/10/06 1:18 AM, in article
> 86393$452674d3$44a4a10d$11521@msgid.meganewsservers.com, "Ray O"
> <rokigawaATtristarassociatesDOTcom> wrote:
>[color=green]
>>
>> "Hammo" <hbaj2006@aapt.net.au> wrote in message
>> news:C14CA46E.DA10%hbaj2006@aapt.net.au...[color=darkred]
>>> Hi Ray O
>>>
>>> You gave me some pointers re: overheating 4AC earlier on.
>>>
>>> I'm still not convinced that it is overheating [1] and have been logging
>>> temp readings. What would Toyota's max temp for the 4AC 1.6 be?[2].
>>>
>>> Cheers
>>>
>>> H
>>>
>>> [1] No coolant loss, no contamination of fluids etc etc and the erratic
>>> nature of tacho and temp gauge (not dissimilar to a volvo and VW that
>>> had
>>> poorly connected voltage regulators on/in the circuitry of the gauge).[/color]
>>
>> By any chance, are there any aftermarket accessories installed like fog
>> lights, audio system, security system, remote start, etc.? If so, check
>> the
>> installation very carefully to make sure any power taps or screws are not
>> causing the problem.[/color]
>
> There are several and I am not convinced that they haven't caused the
> problem. The quickest (and hence most efficient) way to check the actual
> temp was to insert a thermocouple into the coolant stream at roughly the
> same point as the temp sender and compare. The only draw back of this
> method is that I do not know the maximum operating temp slated for the 4AC
> motor.[color=green]
>>
>> This is not easy, but you may want to check to make sure the connectors
>> in
>> the back of the instrument cluster are tight and ground connections are
>> tight. I believe that there is a voltage regulator on the back of the
>> instrument cluster, but they do not fail very often.[/color]
>
> True, but things fail and considering I have experienced this problem
> before
> in other vehicles, I don't consider it outside the realms of probability.
> The thermocouple shows a temp of 110 and the gauge is _above_ red, which
> is
> just not possible (without the usual obvious signs of overheating).[/color]

Assuming that the thermocouple is correct, then the gauge must be incorrect.
[color=blue][color=green][color=darkred]
>>>
>>> [2] I'm guessing 130 degrees Celsius?
>>>[/color]
>>
>> Without looking at the actual specifications, I can't say for sure, but I
>> do
>> not think the max temp is that high. My guess would be in the 115 to 200
>> Celsius range.[/color]
>
> That is the normal op temp, or do you mean max temp that should result in
> the engine being damaged?[color=green]
>>[/color][/color]

Oops! That was a typo! I meant that my guess was 115 to 120 degrees
Celsius. I've since checked the factory repair manual for a Previa, and the
max temp is 110 to 120 degrees Celsius so my guess (at least the one I was
thinking of and not what I typed) was in the right ballpark.

That max temp range is the temp at which the pressure relief in the radiator
cap would open and let the coolant go into the overflow bottle.
[color=blue][color=green]
>> If you can get a hold of a factory repair manual, there are voltage or
>> resistance specifications for temperature sender output. You can measure
>> the voltage at the sender and then again at the instrument cluster to see
>> if
>> they are the same. The repair manual also shows how to diagnose whether
>> the
>> instrument cluster is working or not.[/color]
>
> I have replaced the sender unit and both unit where within a small amount
> of
> the other in terms of voltage. How this translates into temperature, I
> don't have that manual with me, nor do I have with me a device to increase
> the voltage to ensure I have the correct voltage is applied to the gauge.
>
> Many thanks for your input.
>
> Hammo
>[/color]

I'm thinking that the problem is with the voltage regulator at the back of
the instrument cluster. I suspect that replacing it involves replacement
of the entire cluster. As a work around, you can install an aftermarket
temperature sender and gauge.

Sorry I haven't been more help!
--

Ray O
(correct punctuation to reply)

"Hammo" <hbaj2006@aapt.net.au> wrote in message
news:C14D5D7F.E1D9%hbaj2006@aapt.net.au...[color=blue]
>
>
>
> On 7/10/06 1:15 AM, in article dquVg.19$HP.18@trndny08, "Hachiroku"
> <Trueno@ae86.gts> wrote:
>[color=green]
>> On Fri, 06 Oct 2006 14:25:23 +0000, Hammo wrote:
>>[color=darkred]
>>> Hi Ray O
>>>
>>> You gave me some pointers re: overheating 4AC earlier on.
>>>
>>> I'm still not convinced that it is overheating [1] and have been logging
>>> temp readings. What would Toyota's max temp for the 4AC 1.6 be?[2].
>>>
>>> Cheers
>>>
>>> H
>>>
>>> [1] No coolant loss, no contamination of fluids etc etc and the erratic
>>> nature of tacho and temp gauge (not dissimilar to a volvo and VW that
>>> had
>>> poorly connected voltage regulators on/in the circuitry of the gauge).
>>>
>>> [2] I'm guessing 130 degrees Celsius?[/color]
>>
>>
>> 130C seems a bit high! (When you consider 100 is Boiling)[/color]
>
> 100 is only boiling when coolant is pure water and does not include
> dissolved salts. Also, as the coolant is in a pressurised system, boiling
> at 100 would not make any sense.
>[color=green]
>> Now, are you talking COOLANT temps, or are you measuring the engine
>> itself?[/color]
>
> Coolant[color=green]
>>
>> Seems to me on this engine, about 190-200 would be the max for coolant
>> temps (that's Degrees F, BTW)[/color]
>
> Why so low? I have a pressurised system in the 4AC.
>
> Cheers
>
> H
>[/color]

Yup, a pressurized cooling system with a proper mixture of
antifreeze/coolant will raise the boiling temperature, much like a pressure
cooker. This allows the engine to operate at a more efficient temperature
range.

--

Ray O
(correct punctuation to reply)

On 7/10/06 2:26 PM, in article
c18c1$45272cc7$180ffe52$17443@msgid.meganewsservers.com, "Ray O"
<rokigawaATtristarassociatesDOTcom> wrote:
[color=blue]
>
> "Hammo" <hbaj2006@aapt.net.au> wrote in message
> news:C14D5C37.E1D7%hbaj2006@aapt.net.au...[color=green]
>>
>>
>>
>> On 7/10/06 1:18 AM, in article
>> 86393$452674d3$44a4a10d$11521@msgid.meganewsservers.com, "Ray O"
>> <rokigawaATtristarassociatesDOTcom> wrote:
>>[color=darkred]
>>>
>>> "Hammo" <hbaj2006@aapt.net.au> wrote in message
>>> news:C14CA46E.DA10%hbaj2006@aapt.net.au...
>>>> Hi Ray O
>>>>
>>>> You gave me some pointers re: overheating 4AC earlier on.
>>>>
>>>> I'm still not convinced that it is overheating [1] and have been logging
>>>> temp readings. What would Toyota's max temp for the 4AC 1.6 be?[2].
>>>>
>>>> Cheers
>>>>
>>>> H
>>>>
>>>> [1] No coolant loss, no contamination of fluids etc etc and the erratic
>>>> nature of tacho and temp gauge (not dissimilar to a volvo and VW that
>>>> had
>>>> poorly connected voltage regulators on/in the circuitry of the gauge).
>>>
>>> By any chance, are there any aftermarket accessories installed like fog
>>> lights, audio system, security system, remote start, etc.? If so, check
>>> the
>>> installation very carefully to make sure any power taps or screws are not
>>> causing the problem.[/color]
>>
>> There are several and I am not convinced that they haven't caused the
>> problem. The quickest (and hence most efficient) way to check the actual
>> temp was to insert a thermocouple into the coolant stream at roughly the
>> same point as the temp sender and compare. The only draw back of this
>> method is that I do not know the maximum operating temp slated for the 4AC
>> motor.[color=darkred]
>>>
>>> This is not easy, but you may want to check to make sure the connectors
>>> in
>>> the back of the instrument cluster are tight and ground connections are
>>> tight. I believe that there is a voltage regulator on the back of the
>>> instrument cluster, but they do not fail very often.[/color]
>>
>> True, but things fail and considering I have experienced this problem
>> before
>> in other vehicles, I don't consider it outside the realms of probability.
>> The thermocouple shows a temp of 110 and the gauge is _above_ red, which
>> is
>> just not possible (without the usual obvious signs of overheating).[/color]
>
> Assuming that the thermocouple is correct, then the gauge must be incorrect.[/color]

I agree with you here. I wasn't sure what the maximum operating temp would
be and as the temp gauge was constantly in the red, I was getting
uncomfortable about destroying the car![color=blue]
>[color=green][color=darkred]
>>>>
>>>> [2] I'm guessing 130 degrees Celsius?
>>>>
>>>
>>> Without looking at the actual specifications, I can't say for sure, but I
>>> do
>>> not think the max temp is that high. My guess would be in the 115 to 200
>>> Celsius range.[/color]
>>
>> That is the normal op temp, or do you mean max temp that should result in
>> the engine being damaged?[color=darkred]
>>>[/color][/color]
>
> Oops! That was a typo! I meant that my guess was 115 to 120 degrees
> Celsius. I've since checked the factory repair manual for a Previa, and the
> max temp is 110 to 120 degrees Celsius so my guess (at least the one I was
> thinking of and not what I typed) was in the right ballpark.[/color]

I agree with that too. I take it boiling would occur and damage would be
beyond that limit. The aftermarket gauge I got had a bulb on it that was
and inch too long to fit into the temp sender "hole". It had an upper limit
of 267 Farnheit!! The mid range was 116 celcius (~240 F).[color=blue]
>
> That max temp range is the temp at which the pressure relief in the radiator
> cap would open and let the coolant go into the overflow bottle.[/color]
------snippp-------[color=blue][color=green]
>>
>> I have replaced the sender unit and both unit where within a small amount
>> of
>> the other in terms of voltage. How this translates into temperature, I
>> don't have that manual with me, nor do I have with me a device to increase
>> the voltage to ensure I have the correct voltage is applied to the gauge.
>>
>> Many thanks for your input.
>>
>> Hammo
>>[/color]
>
> I'm thinking that the problem is with the voltage regulator at the back of
> the instrument cluster. I suspect that replacing it involves replacement
> of the entire cluster. As a work around, you can install an aftermarket
> temperature sender and gauge.
>
> Sorry I haven't been more help![/color]

You were helpful indeed!

Cheers

Hammo

"Hammo" <hbaj2006@aapt.net.au> wrote in message
news:C14DBBC2.E286%hbaj2006@aapt.net.au...[color=blue]
>
>
>
> On 7/10/06 2:26 PM, in article
> c18c1$45272cc7$180ffe52$17443@msgid.meganewsservers.com, "Ray O"
> <rokigawaATtristarassociatesDOTcom> wrote:
>[color=green]
>>
>> "Hammo" <hbaj2006@aapt.net.au> wrote in message
>> news:C14D5C37.E1D7%hbaj2006@aapt.net.au...[color=darkred]
>>>
>>>
>>>
>>> On 7/10/06 1:18 AM, in article
>>> 86393$452674d3$44a4a10d$11521@msgid.meganewsservers.com, "Ray O"
>>> <rokigawaATtristarassociatesDOTcom> wrote:
>>>
>>>>
>>>> "Hammo" <hbaj2006@aapt.net.au> wrote in message
>>>> news:C14CA46E.DA10%hbaj2006@aapt.net.au...
>>>>> Hi Ray O
>>>>>
>>>>> You gave me some pointers re: overheating 4AC earlier on.
>>>>>
>>>>> I'm still not convinced that it is overheating [1] and have been
>>>>> logging
>>>>> temp readings. What would Toyota's max temp for the 4AC 1.6 be?[2].
>>>>>
>>>>> Cheers
>>>>>
>>>>> H
>>>>>
>>>>> [1] No coolant loss, no contamination of fluids etc etc and the
>>>>> erratic
>>>>> nature of tacho and temp gauge (not dissimilar to a volvo and VW that
>>>>> had
>>>>> poorly connected voltage regulators on/in the circuitry of the gauge).
>>>>
>>>> By any chance, are there any aftermarket accessories installed like fog
>>>> lights, audio system, security system, remote start, etc.? If so,
>>>> check
>>>> the
>>>> installation very carefully to make sure any power taps or screws are
>>>> not
>>>> causing the problem.
>>>
>>> There are several and I am not convinced that they haven't caused the
>>> problem. The quickest (and hence most efficient) way to check the
>>> actual
>>> temp was to insert a thermocouple into the coolant stream at roughly the
>>> same point as the temp sender and compare. The only draw back of this
>>> method is that I do not know the maximum operating temp slated for the
>>> 4AC
>>> motor.
>>>>
>>>> This is not easy, but you may want to check to make sure the connectors
>>>> in
>>>> the back of the instrument cluster are tight and ground connections are
>>>> tight. I believe that there is a voltage regulator on the back of the
>>>> instrument cluster, but they do not fail very often.
>>>
>>> True, but things fail and considering I have experienced this problem
>>> before
>>> in other vehicles, I don't consider it outside the realms of
>>> probability.
>>> The thermocouple shows a temp of 110 and the gauge is _above_ red, which
>>> is
>>> just not possible (without the usual obvious signs of overheating).[/color]
>>
>> Assuming that the thermocouple is correct, then the gauge must be
>> incorrect.[/color]
>
> I agree with you here. I wasn't sure what the maximum operating temp
> would
> be and as the temp gauge was constantly in the red, I was getting
> uncomfortable about destroying the car![color=green]
>>[color=darkred]
>>>>>
>>>>> [2] I'm guessing 130 degrees Celsius?
>>>>>
>>>>
>>>> Without looking at the actual specifications, I can't say for sure, but
>>>> I
>>>> do
>>>> not think the max temp is that high. My guess would be in the 115 to
>>>> 200
>>>> Celsius range.
>>>
>>> That is the normal op temp, or do you mean max temp that should result
>>> in
>>> the engine being damaged?
>>>>[/color]
>>
>> Oops! That was a typo! I meant that my guess was 115 to 120 degrees
>> Celsius. I've since checked the factory repair manual for a Previa, and
>> the
>> max temp is 110 to 120 degrees Celsius so my guess (at least the one I
>> was
>> thinking of and not what I typed) was in the right ballpark.[/color]
>
> I agree with that too. I take it boiling would occur and damage would be
> beyond that limit. The aftermarket gauge I got had a bulb on it that was
> and inch too long to fit into the temp sender "hole". It had an upper
> limit
> of 267 Farnheit!! The mid range was 116 celcius (~240 F).[color=green]
>>
>> That max temp range is the temp at which the pressure relief in the
>> radiator
>> cap would open and let the coolant go into the overflow bottle.[/color]
> ------snippp-------[color=green][color=darkred]
>>>
>>> I have replaced the sender unit and both unit where within a small
>>> amount
>>> of
>>> the other in terms of voltage. How this translates into temperature, I
>>> don't have that manual with me, nor do I have with me a device to
>>> increase
>>> the voltage to ensure I have the correct voltage is applied to the
>>> gauge.
>>>
>>> Many thanks for your input.
>>>
>>> Hammo
>>>[/color]
>>
>> I'm thinking that the problem is with the voltage regulator at the back
>> of
>> the instrument cluster. I suspect that replacing it involves
>> replacement
>> of the entire cluster. As a work around, you can install an aftermarket
>> temperature sender and gauge.
>>
>> Sorry I haven't been more help![/color]
>
> You were helpful indeed!
>
> Cheers
>
> Hammo
>[/color]

Let us know your final resolution. Good luck!
--

Ray O
(correct punctuation to reply)