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1997 Subaru Legacy Outback Limited 2.5L
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21 Posts
Discussion Starter #1
Hey everyone,
I'm somewhat new to the board, and have read quite a few posts and still cant seem to find a solid answer.

Car: 97 Legacy Outback Limited EJ25D (DOHC)
204K Miles on it.
Just replaced timing belt, idlers, tensioner, and adjuster (second time since 97), water pump, failsafe thermo, Hoses, by-pass hose, and power steering pump, radiator cap, and a P1502 Fan Relay Replacement.
I bled the system according to proper Subaru procedures, no water in oil. No oil in water, flushed heater core with hose, and did a block test to check for exhaust gases in coolant (negative).
Still having problems overheating. Everytime ithe vehicle gets hot the[y Resevoir bottle is completley full. Over time thecoolant drains back out of the bottle to almost bone dry.
Before I have replaced all the parts I mentioned, I had punched out the front pre cat only (slightly overheated not major), when I did the 2 O2 sensors and knock sensor.
Could a fuel trim cause it be it lean or rich mixture causing the timing to advance/retard? Under throttle the timing degreee shoots up to 42. At idle the O2 sensor and ST/LT Fuel are normal. Should I replace the CAT before sinking anymore money in? I really want to keep the car and trying my hardest not to have to do the Head Gaskets. ALso the overheating started after all the new parts were replaced. I hhad also flushed out the radiator when I had it out.
 

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1997 Subaru Legacy Outback Limited 2.5L
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21 Posts
Discussion Starter #2 (Edited)
My master tech is stumped. Should I go the New Cat Conv route, New Radiator, or new Water pump? The water pump I put in was a Gates Pump that was part of the of the Timing belt kit. (FYI). I'm really trying to avoid it being the head gasket issue which seems to be common. Also no external leaks on heads. Do I pull the the 2 driver side spark plugs first to check for a possible head problem before i put more money in? Plugs that are in there now are NGK Laser Iridium. I have already wated alot of money on coolant and going to start reusing it. Clean of course. BTW there were no overheating problems before the major maintenance was done. Except the slight temp rise about 1 week after the pre cat was punched out.

Any help will be greatly appreciated. I will also be contacting my guy in the Motorsports division at the Subaru Dealer in the morning to get his opinion as well.

I really wanna keep this car, it is great besides it overheating now.
 

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Lawn ornament XT
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14,366 Posts
I don't know what a failsafe thermo is... but it was only about a year ago that anyone other than Subaru started making thermostats that actually worked right in Subarus.



You wouldn't see any external leak from the heads on a '97. The phase I (dual-cam) 2.5L engine would get leaks between combustion and coolant, but not often an external leak. External leaks (and not internal) were a feature of the Phase II SOHC engine.

Subaru cats don't fail unless the car has been running wrong for a long time. I think you're barking up the wrong tree there.

Pulling out plugs for a leakdown test isn't a terrible idea, once you've verified that the stat is the right kind and not installed backwards- has been known to happen.
 

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2014 OBW 3.6R Limited, 1997 OBW 2.5L Auto (sold, but not forgotten), and 1991 Ford F150
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1,525 Posts
failsafe thermo
I'm not really familiar with a failsafe thermostat, but our cars are notorious for overheating unless a Genuine Subaru thermostat is used. I'd go there first.

Gates pumps are usually pretty good.

I'd re-use the coolant, too, if new or newish.

Good luck.
 

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2013 Outback 3.6L Limited with EyeSight
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218 Posts
Also ensure that the electrical fan is indeed coming on at the appropriate time. The fan relay is a good place to start, but that doesn't mean the fan motor is functioning properly.
 

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1997 Subaru Legacy Outback Limited 2.5L
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21 Posts
Discussion Starter #6
So we narrowed it down to the Catalytic Converter. I had punched out the pre cat (upstream) and replaced O2 sensors and my knock sensor. Cleared my codes and reset all Emission Systems. Usually takes about a week or so to complelety reset all the monitors. About then the car slowly started to overheat. Thats when I had started the timing belt/Thermo/WP and such because i thought the thermo was sticking. Sidenote: Failsafe Thermostats, if they do fail they fail open so it still allows coolant to pass through. MOre or less, I did the Combustion Leak test with the fluid, came out negative. Did a pressure test on the cooling system today and held steady pressure for 45 min or more. With a car running to lean (due to the front cat being punched out) will cause it to overheat. Vice versa with it being to rich (would take alot longer to reach operating temp).
www.ehow.com/how-does_4571194_bad-catalytic-converter-car-overheat.html#ixzz2NxrQc2zE

Scroll down and read Disruption of Air/Fuel Mixture.
I think I may have resovled my own problem with the help from a few friends out by me. Oh besides me doing the pressure test, I also power flushed the cooling system (Block/Heater Core/Radiator) and by-passed the heater core. The Catalytic Conv is my last option. I will post results soon. Need to figure out a way to trick the ECU to run rich to see if it still overheats.

Thanks for your input everyone.
 

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1997 Subaru Legacy Outback Limited 2.5L
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21 Posts
Discussion Starter #7
Just ordered a Cat today. Will be here on Thursday. Ill post results after the Cat is installed.
 

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Registered
1997 Subaru Legacy Outback Limited 2.5L
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21 Posts
Discussion Starter #8
I don't know what a failsafe thermo is... but it was only about a year ago that anyone other than Subaru started making thermostats that actually worked right in Subarus.



You wouldn't see any external leak from the heads on a '97. The phase I (dual-cam) 2.5L engine would get leaks between combustion and coolant, but not often an external leak. External leaks (and not internal) were a feature of the Phase II SOHC engine.

Subaru cats don't fail unless the car has been running wrong for a long time. I think you're barking up the wrong tree there.

Pulling out plugs for a leakdown test isn't a terrible idea, once you've verified that the stat is the right kind and not installed backwards- has been known to happen.
Just a follow up, when I was having problems, the new Thermostat I installed was exactly the same size and length as a OEM Subaru. SO that had nothing to do with it. The seems to be running better with a Decored Thermostat. Lol
 
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