xt6 cooling problems

[st asia]

Hi. I have a 1991 Subaru XT6 AWD auto trans vehicle. It experienced a
bizarre problem yesterday where both the upper and lower radiator hoses
bulged, as well as the overflow tank.

The overflow tank seemed to swell, like a balloon. The car also
expelled a great deal of fluid and pressure through the hose going from
the radiator to the oveflow tank. The antifreeze was in good condition,
but it had been about 15 below zero for the past three days.

When the problem occured, I had been driving for a short period, the
heater worked well and the temperature gauge was just barely off the c
mark. Suddenly, about a block later, the guage went all the way up to H
area, and I pulled into a parking lot, where just at that time the
antifreeze was starting to spurt out under high pressure from the rubber
hose that goes to overflow tank, as well as the overflow tank itself,
which was swelling.

I drove home, all the while with the heater on high to try and bring the
temperature down. Suddenly the car started blowing cold air out of the
heater vents. At that very time I pulled into my garage, shut off the
engine and saw there was still antifreeze being expelled under high
pressure from the overflow hose and tank, and I also noticed the upper
and lower radiator hoses were bulged. I checked the dipstick and was
relieved to not see any water or milky chocolate color.

I let the car sit for about four hours and noticed the upper and lower
radiator hoses had "imploded", just of the opposite of their bulged
condition I had noted earlier. I removed the raditaor cap with great
difficulty, as there was a vacuum in the system.

Any idea what happened and any damage that may have been done? I wonder
if the thermostat failed and the result was the sudden and drastic
buildup of pressure and heat I explained above.

I intend on changing the thermostat (any idea as to which temperature
thermostat is best to use)
and the upper and lower radiator hoses and then starting the car and see
if things are ok.

Any help or suggestions you can provide would be appreciated.

(e-mail address removed)

 

[johninKY]

My guess based on your description of the puffed up radiator etc is either
a cracked cylinder head or blown head gasket. All that excessive pressure
had to come from somewhere.

 

[CompUser]

When the problem occured, I had been driving for a short period, the
heater worked well and the temperature gauge was just barely off the c
mark. Suddenly, about a block later, the guage went all the way up to H
area, and I pulled into a parking lot, where just at that time the
antifreeze was starting to spurt out under high pressure from the rubber
hose that goes to overflow tank, as well as the overflow tank itself,
which was swelling.

Sounds like blown head gasket.

 

[st asia]

My guess based on your description of the puffed up radiator etc is either
a cracked cylinder head or blown head gasket. All that excessive pressure
had to come from somewhere.

Could it have been caused by a stuck thermostat?

 

[Richard Chang]

My guess based on your description of the puffed up radiator etc is either
a cracked cylinder head or blown head gasket. All that excessive pressure
had to come from somewhere.

The extra pressure could be from overheating. I had a Ford Contour
with a water pump that had a plastic impeller. One day the impeller
disintegrated and the water pump no longer functioned. The result was an
overheated engine and coolant coming out of everywhere.

-R.

 

[l.lichtman]

st asia wrote: (clip) I wonder

if the thermostat failed and the result was the sudden and drastic
buildup of pressure and heat I explained above. (clip)

^^^^^^^^^^^^^^^^^^^^
I think you are on the right track. The most optimistic explanation is
that the thermostat failed to open. This would cause the coolant in
the engine block to boil, in about the length of time you describe,
and, of course, bulge the hoses and cause fluids to blow out into the
coolant reserve jar. If you caught it in time, replacing the
thermostat will be both a diagnosis and a cure. It is possible that
the overheating could have caused a blown head gasket. Seems to me that
if you had a blown head gasket, air would have leaked in when it
cooled, and you would not have had a vacuum later. You'll soon know.
Good luck.

 

[johninKY]

I wo nder if the ambient temperature wa a contributing factor? Antifreeze
if not mixed correctly will "freeze" if the mixture is too weak or too
strong. Any chance I could get you to visit/join www.xt6.net?