overheating- 99 outback wagon

[conmadre]

i have a 99 outback wagon 2.5L, and it overheats..

it started a couple of months ago. i had driven for an hour at hight
speeds(70 mph), and when i stopped( for about 5 min)to make a u-turn, the
temp rose to 4/5 hot.. as soon as i moved forward with a little gas, it
dropped like a rock to normal.. nothing more for 2 months, temps stayed
perfect..

about 2 weeks ago it happened again after a long trip at high speeeds, i
slowed down and the temp went up...stayed kind of hot(depending on how
fast i was going) for about 15 minutes as i made my way to the house.
again, it heated after i had slowed down and was entering the city...this
time i saw what i thought must have been oil in the overflow, but my
mechanic said it was just dirt and crud from the sytem.. two mwchanics
have done compression tests and tell me they find no head leaks...

now, after having repaced the water pump, thermostat, pulled and cleaned
the radiator, it will overheat after 30-40 minutes of driving (enough time
to get good and warm, but ONLY when i stop. if i put it into neutral and
rev it up, temp will fall immediately back to normal.

I drove it fast the other day for 1 1/2 hours, cool as can be until i
stopped, temp shot up, i gave it gas(in neutral) and temp drops. there are
a lot of bubbles (and frothing after a while) flowing into the overflow
tank though... up till now i havent really been losing much or any coolant
either...

i am about to get the head gaskets redone just because i have tried
everything else....

what can it be?

 

[Edward Hayes]

Test that your cooling fans are coming on. It could be a bad temp
sensor would be my guess because of what you describe. Car moving
briskly moves air through radiator but, when going slow well you get
the idea. ed

 

[Phil]

this may sound a bit silly, but have you had the gauge checked?

 

[conmadre]

it is definitely overheating...not a temp gauge problem..also the fans work
perfectly

 

[Mickey]

i have a 99 outback wagon 2.5L, and it overheats..

it started a couple of months ago. i had driven for an hour at hight
speeds(70 mph), and when i stopped( for about 5 min)to make a u-turn, the
temp rose to 4/5 hot.. as soon as i moved forward with a little gas, it
dropped like a rock to normal.. nothing more for 2 months, temps stayed
perfect..

about 2 weeks ago it happened again after a long trip at high speeeds, i
slowed down and the temp went up...stayed kind of hot(depending on how
fast i was going) for about 15 minutes as i made my way to the house.
again, it heated after i had slowed down and was entering the city...this
time i saw what i thought must have been oil in the overflow, but my
mechanic said it was just dirt and crud from the sytem.. two mwchanics
have done compression tests and tell me they find no head leaks...

now, after having repaced the water pump, thermostat, pulled and cleaned
the radiator, it will overheat after 30-40 minutes of driving (enough time
to get good and warm, but ONLY when i stop. if i put it into neutral and
rev it up, temp will fall immediately back to normal.

I drove it fast the other day for 1 1/2 hours, cool as can be until i
stopped, temp shot up, i gave it gas(in neutral) and temp drops. there are
a lot of bubbles (and frothing after a while) flowing into the overflow
tank though... up till now i havent really been losing much or any coolant
either...

i am about to get the head gaskets redone just because i have tried
everything else....

what can it be?

What brand t-stat? I've found non-factory t-stat don't have as large
a passage as factory part. Have you ever added any "stop leak" kind
of product? Subie rads have very small passages and these kind of
products can and do block the radiator. BTDT. Any chance there is
air still trapped in the cooling system from prior service?

Lastly you may have a head gasket problem.

Mickey