I have a subaru with 230,000 (mostly interstate) miles on it. It's a
1998 legacy limited GT model with a 2.5 liter phase II engine. This
engine does not have the turbo installed. Whomever had it before me
optioned this out. I baught it at 70,000 miles. The car is fully loaded
so buying a new car is out of the question, plus, it's a subaru.
Anyway, the engine can sit in idle for hours upon hours at a time (4
hours running so far). The engine temp stays normal. As soon as the car
is driven 2-3 miles down the road, the car overheats (needle goes all
the way to the top immediately). The car has been tested for exhaust in
the radiator, fluid in the exhaust, test after test. Block engine
tests, they all pass. A colored fluid was placed in the radiator to
show possible leaks using a blacklight, nothing. Nothing in the
exhaust, nothing on the outside of the engine, not a clue as to the
underlying problem. The possible Blown Head Gasket isn't showing any
signs whatsoever. No leaks, no signs, nothing. The mechaninc seems to
think it's a faulty water pump. They said the top hose from the engine
to the radiator is hot and the bottom hose to the engine is cold. They
said the bottom hose shouldn't be cold, rather cool. Has anyone ever
had this problem? The thermostat has been replaced with a brand new
one. They say the radiator is in good shape. 1 week prior to this the
engine went hot and I let it cool down, then put a 50/50 solution in
and all was ok (maybe low on fluid? as the overflow tank was empty) The
engine didn't knock or jump before the overheat and was only driven 10
miles at most after the 2nd overheat and towed back. The car is in
excellent condition with a brand new tune up not 3 weeks before (by the
same mechanic who is studying this puzzle of an engine) and a brand new
oil change. Does anyone know what this might be? or heard of such a
thing? A BHG was considred and the blue to yellow fluid passed, yellow
fluid in the radiator passed, fluid in the exhast passed and all other
tests passed. When the temp went hot the first time noticed was the
cool air blowing out rather than heat. (Mechanic trated it as an air
pocket and bled the system) Now the system has been bled about 4 times
to remove any and all air pockets. We just can't figure it out! Please
help!! Thank you

RIPTYDE

Your problem is poor or no coolant circulation. If you are absolutely sure
there is no air pocket and the radiator is good, it has to be imo the water
pump and/or collapsing radiator hoses. I would replace the pump and hoses
and have the radiator checked for flow at the same time.

Riptyde wrote:
Wow!
Um - has the radiator cap been replaced and the overflow hose checked
for blockage,etc.?
Also, I wonder if a partially blocked catalytic converter could cause an
engine to overheat? (naturally I'd expect the rear O2 sensor to throw a
code) oh yeah - any ECU codes stored?

Carl


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to reply, change ( .not) to ( .net)

Is the engine really overheating or is it just a gauge issue?

Riptyde wrote: