2002 P.T. Cruiser Overheating Problems?

"Bob AZ" > wrote in message
...
> Don
>
> I have read the several replies to your query. Should not the Coolant
> Overflow System/Reservoir take care of ridding any bubbles from the
> coolant system?

If a head gasket is failing then the compression stoke will produce a lot
of gasses going into the coolant - endless supply of bubbles.

As for trapped air - you obviously never had a fishtank with a
side-mount filter that used siphon hoses to draw water from
the tank.

Ted

Ted Mittelstaedt wrote:

> As for trapped air - you obviously never had a fishtank with a
> side-mount filter that used siphon hoses to draw water from
> the tank.

An engine cooling system doesn't rely on a siphon. However, the OP
asked why the bubbles wouldn't bleed off into the overflow tank.
Normally the overflow tube is on the low pressure side of the radiator
cap. In order for anything to go into that tank pressure would have to
build high enough. Bubbles won't cause that.

miles wrote:
> Ted Mittelstaedt wrote:
>
>> As for trapped air - you obviously never had a fishtank with a
>> side-mount filter that used siphon hoses to draw water from
>> the tank.
>
> An engine cooling system doesn't rely on a siphon. However, the OP
> asked why the bubbles wouldn't bleed off into the overflow tank.
> Normally the overflow tube is on the low pressure side of the radiator
> cap. In order for anything to go into that tank pressure would have to
> build high enough. Bubbles won't cause that.

That's not how many modern "overflow" tanks work. They are actually part
of the pressurized system, and coolant is pumped THROUGH them
continually. They're really not an "overflow" tank anymore, they're more
akin to a surge tank on an old liquid-cooled aircraft engine, only
pressurized.

Steve wrote:

> That's not how many modern "overflow" tanks work. They are actually part
> of the pressurized system, and coolant is pumped THROUGH them
> continually. They're really not an "overflow" tank anymore, they're more
> akin to a surge tank on an old liquid-cooled aircraft engine, only
> pressurized.

I've thought I saw what I think you are referring to. They always say
to add fluid to that tank and never take off the radiator cap to do so.
However, the tank is still a thin walled plastic tank with a non
pressurized cap. So guess I haven't seen what you're referring to!

Miles > writes:

> Steve wrote:
>
>> That's not how many modern "overflow" tanks work. They are actually
>> part of the pressurized system, and coolant is pumped THROUGH them
>> continually. They're really not an "overflow" tank anymore, they're
>> more akin to a surge tank on an old liquid-cooled aircraft engine,
>> only pressurized.
>
> I've thought I saw what I think you are referring to. They always say
> to add fluid to that tank and never take off the radiator cap to do
> so. However, the tank is still a thin walled plastic tank with a non
> pressurized cap. So guess I haven't seen what you're referring to!

I find my wife's 2000 Intrepid really frustrating -- if I can believe
the FSM, it really does have a conventional overflow tank -- but the
overflow tank and pressure tank are molded in a single piece. The
only cap is the pressure cap. The "correct" way to fill it is to put
on a special funnel that mates to the pressure cap fitting. The
result is that there is *always* air in the system.

Hmmm... it actually looks like I could puncture the overflow side so
I could fill it, and put a cork in it...

Joe Pfeiffer wrote:
> Miles > writes:
>
>> Steve wrote:
>>
>>> That's not how many modern "overflow" tanks work. They are actually
>>> part of the pressurized system, and coolant is pumped THROUGH them
>>> continually. They're really not an "overflow" tank anymore, they're
>>> more akin to a surge tank on an old liquid-cooled aircraft engine,
>>> only pressurized.
>> I've thought I saw what I think you are referring to. They always say
>> to add fluid to that tank and never take off the radiator cap to do
>> so. However, the tank is still a thin walled plastic tank with a non
>> pressurized cap. So guess I haven't seen what you're referring to!
>
> I find my wife's 2000 Intrepid really frustrating -- if I can believe
> the FSM, it really does have a conventional overflow tank -- but the
> overflow tank and pressure tank are molded in a single piece. The
> only cap is the pressure cap. The "correct" way to fill it is to put
> on a special funnel that mates to the pressure cap fitting. The
> result is that there is *always* air in the system.
>
> Hmmm... it actually looks like I could puncture the overflow side so
> I could fill it, and put a cork in it...

I believe both sides of the reservoir are pressurized - IOW I don't
believe that the "overflow" side is vented to the outside as that would
require some sort of isolation valving between the two compartments, and
I don't believe their is any. I haven't understood the purpose of that
funnel, and don't have or use it on either of my two Concordes (same car
for this discussion as your wife's Intrepid), and have never had any
problems after servicing and refilling the coolant system.

The idea is that the coolant continuously circulates thru the pressure
chamber (when the engine is running) and any air in the system will find
its way there and be trapped there, so the rest of the system is air
free. There is a bleeder valve in the intake area that is supposed to be
open when refilling to prevent air being trapped in the block during
refill. Any small amount of air will then make its way to the reservoir
when the engine is run in normal subsequent driving.

--
Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

Bill Putney > writes:

> Joe Pfeiffer wrote:
>>
>> I find my wife's 2000 Intrepid really frustrating -- if I can believe
>> the FSM, it really does have a conventional overflow tank -- but the
>> overflow tank and pressure tank are molded in a single piece. The
>> only cap is the pressure cap. The "correct" way to fill it is to put
>> on a special funnel that mates to the pressure cap fitting. The
>> result is that there is *always* air in the system.
>>
>> Hmmm... it actually looks like I could puncture the overflow side so
>> I could fill it, and put a cork in it...
>
> I believe both sides of the reservoir are pressurized - IOW I don't
> believe that the "overflow" side is vented to the outside as that
> would require some sort of isolation valving between the two
> compartments, and I don't believe their is any. I haven't understood
> the purpose of that funnel, and don't have or use it on either of my
> two Concordes (same car for this discussion as your wife's Intrepid),
> and have never had any problems after servicing and refilling the
> coolant system.
>
> The idea is that the coolant continuously circulates thru the pressure
> chamber (when the engine is running) and any air in the system will
> find its way there and be trapped there, so the rest of the system is
> air free. There is a bleeder valve in the intake area that is supposed
> to be open when refilling to prevent air being trapped in the block
> during refill. Any small amount of air will then make its way to the
> reservoir when the engine is run in normal subsequent driving.

I guess the FSM doesn't actually say the overflow chamber isn't
pressurized -- but it refers to the other chamber as the "pressure
chamber", and the path to the overflow chamber is by way of the
radiator pressure cap.

I've never had any actual problems, either. It just annoys me.....

Miles wrote:
> Steve wrote:
>
>> That's not how many modern "overflow" tanks work. They are actually
>> part of the pressurized system, and coolant is pumped THROUGH them
>> continually. They're really not an "overflow" tank anymore, they're
>> more akin to a surge tank on an old liquid-cooled aircraft engine,
>> only pressurized.
>
> I've thought I saw what I think you are referring to. They always say
> to add fluid to that tank and never take off the radiator cap to do so.
> However, the tank is still a thin walled plastic tank with a non
> pressurized cap. So guess I haven't seen what you're referring to!

No, the kind I'm referring to can be found on first-gen LH cars, for
example. Thick-walled plastic WITH a pressure cap ON the plastic tank,
and no other radiator cap.

I *think* the PT uses the same type, but its been so long since I've
looked under the hood of a PT that I don't remember.

Joe Pfeiffer wrote:
> Miles > writes:
>
>> Steve wrote:
>>
>>> That's not how many modern "overflow" tanks work. They are actually
>>> part of the pressurized system, and coolant is pumped THROUGH them
>>> continually. They're really not an "overflow" tank anymore, they're
>>> more akin to a surge tank on an old liquid-cooled aircraft engine,
>>> only pressurized.
>> I've thought I saw what I think you are referring to. They always say
>> to add fluid to that tank and never take off the radiator cap to do
>> so. However, the tank is still a thin walled plastic tank with a non
>> pressurized cap. So guess I haven't seen what you're referring to!
>
> I find my wife's 2000 Intrepid really frustrating -- if I can believe
> the FSM, it really does have a conventional overflow tank -- but the
> overflow tank and pressure tank are molded in a single piece. The
> only cap is the pressure cap. The "correct" way to fill it is to put
> on a special funnel that mates to the pressure cap fitting. The
> result is that there is *always* air in the system.
>
> Hmmm... it actually looks like I could puncture the overflow side so
> I could fill it, and put a cork in it...

Hmmm.... no bleeder on the T-stat housing on 2nd-Gen LH cars??

Other than the fact that the bleeder is so nearly at the same level as
the overflow tank that it takes too long to force the last of the air
out of the system, I have no complaints with the first-gen system. I had
expected that pressure tank to promptly explode when the warranty
expired, but here we are 15 years and 250k miles later, still going
(knock wood).

Steve > writes:
>
> Hmmm.... no bleeder on the T-stat housing on 2nd-Gen LH cars??

No, the bleeder is there (though the thermostat has been moved away
from that housing to a location down on the side). My annoyance is
that I find it nearly impossible to see the level of the coolant in
the pressure tank due to the tank being nearly opaque and the dye
being very light in color; I can only check the level with with any
confidence with a cold engine.

> Other than the fact that the bleeder is so nearly at the same level as
> the overflow tank that it takes too long to force the last of the air
> out of the system, I have no complaints with the first-gen system. I
> had expected that pressure tank to promptly explode when the warranty
> expired, but here we are 15 years and 250k miles later, still going
> (knock wood).