Need help from VW techs re fluctuating coolant overflow tank levels

I have a 2003 GTI VR6, with over 24K miles. The coolant level, when
cold, was always just below the MAX level in the overflow tank. About
a month ago, I backed the car out of the garage one morning, and
shifted into first. The coolant light began flashing and the chime
went off. I stopped and checked the coolant level. It was below the
MIN mark. I pulled back into the garage and added distilled water to
bring it up to the MIN mark. (I didn't have any G12 coolant at the
time.) It took 6 ounces of distilled water. The light did not come
back on.

Since then the coolant level, when cold, is usually half way tween the
MIN and MAX marks. But, sometimes its at the MAX mark and sometimes
it's 1/4" below the MIN mark (altho the light does not come on). The
temp gauge reads at the right end of the 190 degree hash mark. The car
does not overheat.

Why don't I have a similar amount of coolant in the overflow tank each
morning? It would seem that I don't have a coolant leak. It would
also seem that if the amount of coolant in the system is constant, then
as the overflow tank amounts vary, so do the amounts of coolant in the
radiator and engine block. The dealer says the cooling system is
operating perfectly (they don't understand why the overflow tank amount
varies either), and to keep an eye on the overflow tank amount.

Any thoughts or ideas from anyone? I just have this idea that
something must be wrong or I wouldn't have the overflow tank
fluctuations that I have on an almost daily basis.

you may have the beginning of a leak, but it's to small to detect yet. Just
keep an eye on the level and see what happens. Some fluctuation could be
caused by the expansion/contraction of the coolant and hoses at various
temperatures. after all the hoses are rubber.


> wrote in message
oups.com...
>I have a 2003 GTI VR6, with over 24K miles. The coolant level, when
> cold, was always just below the MAX level in the overflow tank. About
> a month ago, I backed the car out of the garage one morning, and
> shifted into first. The coolant light began flashing and the chime
> went off. I stopped and checked the coolant level. It was below the
> MIN mark. I pulled back into the garage and added distilled water to
> bring it up to the MIN mark. (I didn't have any G12 coolant at the
> time.) It took 6 ounces of distilled water. The light did not come
> back on.
>
> Since then the coolant level, when cold, is usually half way tween the
> MIN and MAX marks. But, sometimes its at the MAX mark and sometimes
> it's 1/4" below the MIN mark (altho the light does not come on). The
> temp gauge reads at the right end of the 190 degree hash mark. The car
> does not overheat.
>
> Why don't I have a similar amount of coolant in the overflow tank each
> morning? It would seem that I don't have a coolant leak. It would
> also seem that if the amount of coolant in the system is constant, then
> as the overflow tank amounts vary, so do the amounts of coolant in the
> radiator and engine block. The dealer says the cooling system is
> operating perfectly (they don't understand why the overflow tank amount
> varies either), and to keep an eye on the overflow tank amount.
>
> Any thoughts or ideas from anyone? I just have this idea that
> something must be wrong or I wouldn't have the overflow tank
> fluctuations that I have on an almost daily basis.
>

you may have the beginning of a leak, but it's to small to detect yet. Just
keep an eye on the level and see what happens. Some fluctuation could be
caused by the expansion/contraction of the coolant and hoses at various
temperatures. after all the hoses are rubber.


> wrote in message
oups.com...
>I have a 2003 GTI VR6, with over 24K miles. The coolant level, when
> cold, was always just below the MAX level in the overflow tank. About
> a month ago, I backed the car out of the garage one morning, and
> shifted into first. The coolant light began flashing and the chime
> went off. I stopped and checked the coolant level. It was below the
> MIN mark. I pulled back into the garage and added distilled water to
> bring it up to the MIN mark. (I didn't have any G12 coolant at the
> time.) It took 6 ounces of distilled water. The light did not come
> back on.
>
> Since then the coolant level, when cold, is usually half way tween the
> MIN and MAX marks. But, sometimes its at the MAX mark and sometimes
> it's 1/4" below the MIN mark (altho the light does not come on). The
> temp gauge reads at the right end of the 190 degree hash mark. The car
> does not overheat.
>
> Why don't I have a similar amount of coolant in the overflow tank each
> morning? It would seem that I don't have a coolant leak. It would
> also seem that if the amount of coolant in the system is constant, then
> as the overflow tank amounts vary, so do the amounts of coolant in the
> radiator and engine block. The dealer says the cooling system is
> operating perfectly (they don't understand why the overflow tank amount
> varies either), and to keep an eye on the overflow tank amount.
>
> Any thoughts or ideas from anyone? I just have this idea that
> something must be wrong or I wouldn't have the overflow tank
> fluctuations that I have on an almost daily basis.
>

Thanks. I don't think there's a coolant leak because the level
recovers at times. As a follow up, I brought the car to the dealer.
When I drove it to the dealer the cold level was a 1/4" below the MIN.
The dealer did a pressure check and said everything's okay. The next
morning, the cold level was 3/4" above the MAX. This is a pretty big
increase in overflow level. I'm thinking re-pressurizing the system to
do the pressure check resulted in the big increase in the overflow
level. That's another reason why I don't think there's a coolant leak.

I live in Phoenix, so we don't have much of a temperature variation.
Also, the car is garaged overnight. So, the garage temp is equal to or
even above the outside temp here in the winter. Wondering if I have a
slow pressure leak, which, when the pressure drops too much, the system
re-pressurizes itself and then goes thru the cycle again, and again?
Or, could going from a warm garage to a colder outside have something
to do with this? I would like to think the hoses are less sensitive
than this because they have to deal with coolant temps at 190 degrees F
for normal operation. Oh yea, the car does not overheat and the
coolant temp, when hot, is the same now as before this all started.

Thanks. I don't think there's a coolant leak because the level
recovers at times. As a follow up, I brought the car to the dealer.
When I drove it to the dealer the cold level was a 1/4" below the MIN.
The dealer did a pressure check and said everything's okay. The next
morning, the cold level was 3/4" above the MAX. This is a pretty big
increase in overflow level. I'm thinking re-pressurizing the system to
do the pressure check resulted in the big increase in the overflow
level. That's another reason why I don't think there's a coolant leak.

I live in Phoenix, so we don't have much of a temperature variation.
Also, the car is garaged overnight. So, the garage temp is equal to or
even above the outside temp here in the winter. Wondering if I have a
slow pressure leak, which, when the pressure drops too much, the system
re-pressurizes itself and then goes thru the cycle again, and again?
Or, could going from a warm garage to a colder outside have something
to do with this? I would like to think the hoses are less sensitive
than this because they have to deal with coolant temps at 190 degrees F
for normal operation. Oh yea, the car does not overheat and the
coolant temp, when hot, is the same now as before this all started.

A pressure test may show leaks where the hoses or something is letting
fluid out. You can have head gasket leaks that pressurizes the system
or maybe pump some air in a passage. This air could displace the
coolant and make the coolant appear high. If you get the right
condition where this air burps out the coolant could read low.

Coolant temps are hotter than 190. You are reading the temp at a place
where it is cool. Your system is pressurized and has
anti-freeze/antiboil solution to raise the boiling point. If you want
to confirm this hotter than 190 theory get out your infared
thermometer. It will not measure the temps in the water jacket though.
Just plain water can boil away in the waterjacket significantly
reducing the cooling capacity.

wrote:

>Thanks. I don't think there's a coolant leak because the level
>recovers at times. As a follow up, I brought the car to the dealer.
>When I drove it to the dealer the cold level was a 1/4" below the MIN.
>The dealer did a pressure check and said everything's okay. The next
>morning, the cold level was 3/4" above the MAX. This is a pretty big
>increase in overflow level. I'm thinking re-pressurizing the system to
>do the pressure check resulted in the big increase in the overflow
>level. That's another reason why I don't think there's a coolant leak.
>
>I live in Phoenix, so we don't have much of a temperature variation.
>Also, the car is garaged overnight. So, the garage temp is equal to or
>even above the outside temp here in the winter. Wondering if I have a
>slow pressure leak, which, when the pressure drops too much, the system
>re-pressurizes itself and then goes thru the cycle again, and again?
>Or, could going from a warm garage to a colder outside have something
>to do with this? I would like to think the hoses are less sensitive
>than this because they have to deal with coolant temps at 190 degrees F
>for normal operation. Oh yea, the car does not overheat and the
>coolant temp, when hot, is the same now as before this all started.


Jim B.

A pressure test may show leaks where the hoses or something is letting
fluid out. You can have head gasket leaks that pressurizes the system
or maybe pump some air in a passage. This air could displace the
coolant and make the coolant appear high. If you get the right
condition where this air burps out the coolant could read low.

Coolant temps are hotter than 190. You are reading the temp at a place
where it is cool. Your system is pressurized and has
anti-freeze/antiboil solution to raise the boiling point. If you want
to confirm this hotter than 190 theory get out your infared
thermometer. It will not measure the temps in the water jacket though.
Just plain water can boil away in the waterjacket significantly
reducing the cooling capacity.

wrote:

>Thanks. I don't think there's a coolant leak because the level
>recovers at times. As a follow up, I brought the car to the dealer.
>When I drove it to the dealer the cold level was a 1/4" below the MIN.
>The dealer did a pressure check and said everything's okay. The next
>morning, the cold level was 3/4" above the MAX. This is a pretty big
>increase in overflow level. I'm thinking re-pressurizing the system to
>do the pressure check resulted in the big increase in the overflow
>level. That's another reason why I don't think there's a coolant leak.
>
>I live in Phoenix, so we don't have much of a temperature variation.
>Also, the car is garaged overnight. So, the garage temp is equal to or
>even above the outside temp here in the winter. Wondering if I have a
>slow pressure leak, which, when the pressure drops too much, the system
>re-pressurizes itself and then goes thru the cycle again, and again?
>Or, could going from a warm garage to a colder outside have something
>to do with this? I would like to think the hoses are less sensitive
>than this because they have to deal with coolant temps at 190 degrees F
>for normal operation. Oh yea, the car does not overheat and the
>coolant temp, when hot, is the same now as before this all started.


Jim B.

wrote:
> A pressure test may show leaks where the hoses or something is
letting
> fluid out. You can have head gasket leaks that pressurizes the system
> or maybe pump some air in a passage. This air could displace the
> coolant and make the coolant appear high. If you get the right
> condition where this air burps out the coolant could read low.
>

Are you saying I have a head gasket leak? Wouldn't there be other
indications of a head gasket leak, such as coolant and oil mixing?

> Coolant temps are hotter than 190. You are reading the temp at a
place
> where it is cool. Your system is pressurized and has
> anti-freeze/antiboil solution to raise the boiling point. If you want
> to confirm this hotter than 190 theory get out your infared
> thermometer. It will not measure the temps in the water jacket
though.
> Just plain water can boil away in the waterjacket significantly
> reducing the cooling capacity.
>

I'm reading the water temp off the dash gauge. Isn't the purpose of a
sealed pressurized cooling system to capture boiled water vapors (using
the overflow tank) so the cooled back into water can be put back into
the radiotor (using the pressurized vacuum)?

I'm confused. Are you saying I might have a head gasket lead (even
without any other indications) or that my cooling system is functioning
normally? Thanks.

wrote:
> A pressure test may show leaks where the hoses or something is
letting
> fluid out. You can have head gasket leaks that pressurizes the system
> or maybe pump some air in a passage. This air could displace the
> coolant and make the coolant appear high. If you get the right
> condition where this air burps out the coolant could read low.
>

Are you saying I have a head gasket leak? Wouldn't there be other
indications of a head gasket leak, such as coolant and oil mixing?

> Coolant temps are hotter than 190. You are reading the temp at a
place
> where it is cool. Your system is pressurized and has
> anti-freeze/antiboil solution to raise the boiling point. If you want
> to confirm this hotter than 190 theory get out your infared
> thermometer. It will not measure the temps in the water jacket
though.
> Just plain water can boil away in the waterjacket significantly
> reducing the cooling capacity.
>

I'm reading the water temp off the dash gauge. Isn't the purpose of a
sealed pressurized cooling system to capture boiled water vapors (using
the overflow tank) so the cooled back into water can be put back into
the radiotor (using the pressurized vacuum)?

I'm confused. Are you saying I might have a head gasket lead (even
without any other indications) or that my cooling system is functioning
normally? Thanks.

There are 3 passages in a head gasket. Or 3 types of openings. The
combustion chamber, the coolant pasages and the oil passages. The
passages in the gaskets are not all close to the outside of the
engine. Some may be right in the middle of the block or head. You can
have head gaskets leaking with no external signs. It is possible that
there is a void between the combustion chamber and a water passage.

I am saying that something weird is going on. I am saying that you
could have a leaking head gasket. I am saying that pressurized tests
do not always show leaks. When you work on air conditioning systems
you can leak test using pressure. You can leak test using vacuum also.
Note that there are some tests done with a hot engine, some done with
a cold engine. I define a hot engine as one with the oil temperature
at the normal temp after the car has been driven at highway speeds for
15-20 minutes. A gas engine can show normal water temp in 10 minutes
of city driving but the oil temp has not risen to normal temp.

Have you ever looked at a head gasket? Ask at the parts store if they
have one you can look at and if the parts counter person knows about
the egine for the gasket he/she can point out how all those holes have
different functions. Oil, water and combustion.

A good radiator shop may be able to offer a better diagnosis.

wrote:

>
wrote:
>> A pressure test may show leaks where the hoses or something is
>letting
>> fluid out. You can have head gasket leaks that pressurizes the system
>> or maybe pump some air in a passage. This air could displace the
>> coolant and make the coolant appear high. If you get the right
>> condition where this air burps out the coolant could read low.
>>
>
>Are you saying I have a head gasket leak? Wouldn't there be other
>indications of a head gasket leak, such as coolant and oil mixing?
>
>> Coolant temps are hotter than 190. You are reading the temp at a
>place
>> where it is cool. Your system is pressurized and has
>> anti-freeze/antiboil solution to raise the boiling point. If you want
>> to confirm this hotter than 190 theory get out your infared
>> thermometer. It will not measure the temps in the water jacket
>though.
>> Just plain water can boil away in the waterjacket significantly
>> reducing the cooling capacity.
>>
>
>I'm reading the water temp off the dash gauge. Isn't the purpose of a
>sealed pressurized cooling system to capture boiled water vapors (using
>the overflow tank) so the cooled back into water can be put back into
>the radiotor (using the pressurized vacuum)?
>
>I'm confused. Are you saying I might have a head gasket lead (even
>without any other indications) or that my cooling system is functioning
>normally? Thanks.


Jim B.