Try solving this overheating puzzle? [Archive]

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joedog916

08-20-2010, 03:53 PM

I have a 2000 Legacy GT 2.5. In August and September of 2009, i replaced my Radiator and cap, Water pump, Tstat, and Head gaskets. Now, my car is overheating again, I replaced a new Tstat for starters. Heres the puzzle. When idling, the car is fine, go to drive it, and then it overheats. Fans turn on, water pumps, no leaks, not Heater core, no Hydrocarbons in radiator, Rad cap holds pressure, not a collapsing hose, no engine codes, oil is fine, no power loss. It only seems to overheat, when there is a load on the engine. 1 question though, if my Catco's are part blocked causing backpressure, will it show emissions in the coolant, or does the pressure have to blow the gaskets first? Even the shop my car is at are puzzled, i only took it there because the Head gaskets are under warranty if that was the problem.

BG5guy

08-20-2010, 04:42 PM

imma say either head gaskets are bad or a warped head

Airgne

08-20-2010, 06:37 PM

your head might be warped like bg5 said. also you would have a clog in you water jackets. the subaru coolant conditioner is not a good thing. its just used to get the warranty.

Sarra

08-20-2010, 08:20 PM

Only overheats when there is a load on the engine...

Oh hoh. Is the car really low on power? I'm going to guess that you are running super retarded timing, and you've got combustion happening in your heads, and you're super heating your waterjackets.

ouch1011

08-21-2010, 02:47 AM

^^ I'm 90% sure retarded timing won't cause a hot condition. Advanced timing will. And besides, if the timing were that retarded, there would be a significant power loss. OP says no loss of power.

Do you still get heat from the heater when its overheating? Does the cooling fan blow hot air? Is there is a difference in temp between the upper and lower hoses? Question 1 determines if you have any coolant flow at all. Question 2 and 3 determine if you have flow through the radiator.

JunkerXL

08-26-2010, 11:24 AM

2.5.... :smt017 im goin with heads or head gaskets on this one, wouldn't hurt make sure there is no air in the system either, though i dont think thats the issue :neutral: hope you get it solved. on the plus side, subaru failure is almost always time for subaru upgrade :smt023

:smt020

httrdd

08-26-2010, 01:16 PM

I am going to say partially blocked water jacket. It lets the coolant through under no load, but when the water pump spins faster for the higher demand it cannot keep up.

JunkerXL

08-26-2010, 01:32 PM

if thats the case, back flush the poo out of it, might make it go away. i used purple power cleaner when i did my 83 rolla, and back flushed till clean. over heating stopped :)

joedog916

08-27-2010, 03:50 PM

Thanks for all the responses. Apparently, it turned out to be just a bad thermostat, "according to the shop". So, i guess the Brand New OEM tstat i bought and put in was no good. Drove it hard in 100 degree weather and it doesn't overheat anymore. Well see though as time goes on.

httrdd

08-27-2010, 04:00 PM