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Old 02-24-2001, 01:07 PM   #1
P.K. Motorsports
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Join Date: Mar 2000
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1999 RS
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As you are no doubt aware the freeway is typically where your engine runs at its coolest. The loss of fluid in your cooling system is worrisome - have you ever observed a leak? I'm going to bet you have a broken thermostat and possibly some problem with the water pump, because I can't think of too many other things which could overheat the engine on the freeway but not at low speeds.

By the way, adjusting the AFC settings at partial throttle does nothing. Your ECU adjusts the rich/lean mixture based largely upon on exhaust O<sub>2</sub> content and thus will correct your mixture around your settings immediately. If your engine is running lean on the freeway but not at WOT then it might be as simple as an O<sub>2</sub> sensor replacement. If that were really the case you should be getting CE lights, though.

Edit: fixed subscript

[This message has been edited by P.K. Motorsports (edited February 24, 2001).]
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Old 02-24-2001, 02:40 PM   #2
SteveS
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You might have a bad head gasket (or two). Just a guess, but if you don't observe any leaking, then this would be my bet. You probably get away with it on the track, with it slowly "disappearing" and then you see the results of the problem on the freeway.

Good luck.

Steve
http://www.lagging.com/ <- currently DOWN for some d@mn reason
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Old 02-24-2001, 07:49 PM   #3
mcgyver
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Jason, which car were you?

I was there with the Black '98 that Overheated all day, without a thermostat. Mine has been unofficially determined that it is the head gasket. The bad head gasket is letting the combustion push-out the coolant out of the engine. So, when enough coolant is out, it starts to heat up.

I filled the radiator up before we went home last night and it ran COLD the whole way home @ 90+.

Also, Adrian too Overheated at Track Day, his is also a MY98. He had to limp home @ 55.

Mine's going in soon for head gaskets

Adam
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Old 02-25-2001, 12:39 AM   #4
Jason
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WHT

Have a Nice Day? Overheating! on freeway??!!

After driving 2 hrs to Thunderhill for the Subaru Track day, I noticed the engine's water temp started to cline slowly. I was only doing @85mph and the outside temp was slightly above 40F.

Checked the raditor, it was near empty. After filled with water again, I prayed it would not leak again.

Next morning, no sign of leak. Headed to track, beat the hell out of the car, no overheat!

After the event, I headed home @80mph and it OVERHEATED again!!!!

This is getting very weird. Track driving and local driving will not overheat the car, but on freeway in a cold day??!!

At this time, I turned the SAFC Lo-throttle to +10% about 3K & 4Krpm hoping it will run cooler with super rich condition.

Any suggestions? could it be as simple as a radiator cap or could it be as major as an ECU malfunction?
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Old 02-25-2001, 12:57 AM   #5
Jason
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I had the only wht MY00 Legacy on the track.
When I was on my way home, reserve coolant was almost full while radiator level was low. Strange thing is, it did NOT overheat on Track or low speed cruising.

I had hooked up the AFC blue wire to rear O2 sensor. During highway @ 80mph, it was reading about 0.4~0.5V. Before it was about 0.7V. I assume the engine was running super lean thus causing the overheat.

After adjusting the SAFC 10%+ @ crusing rpm and doing 70mph, I made it home without anymore overheating issue. But I do not know if the SAFC worked or lower speed crusing worked.

I will take the car to Santa Cruz next weekend for some inspection.
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Old 02-25-2001, 09:41 AM   #6
Tensecgn
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(1) see if the fans are comming on
(2)Pressure test your radiator cap.If it cannot hold pressure that would explain the full overflow bottle and the coolant system can`t suck the coolant back to the engine.
(3)With the car running at normal temp check to see if you have any cold spots on your radiator.
(4)check the t-stat by pulling it out and putting it in water and putting it on the stove with a temp gauge on it to see if it`s working correctly.
(5)Do a leak down test to verify that a headgasket is blown.
Tony
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Old 02-25-2001, 01:53 PM   #7
Jgrahn555
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Have a Nice Day?

That's exactly what happened to me and my 1st gen. legacy a couple months back.

cheap way: Take off your radiator cap, smell it. If it smells like exhaust fumes, it's the head gasket.

the right way: Getting a leakdown test is the best way to finalize what's really wrong with the car.

If you get the head gasket(s) done at the dealer, it will most likely run about $1200+, if you do it yourself with a buddy and a shop manual, it'll be about $500.

Plan to resurface the flywheel while you have the engine out. And if you want to upgrade your clutch, nows the time.

Jason
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Old 02-25-2001, 02:06 PM   #8
ColinL
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Why would you have the engine out to replace the head gaskets?
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Old 02-26-2001, 10:49 AM   #9
Joel Gat, 1.8L
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HEllo,

Colin, because it's a royal pain in the rear end to take the heads off with the engine in the bay, ESPECIALLY if you're doing it at home and you don't have access to a lift. I've done it both ways and it takes less time to pull the engine and take the heads off than to lay on the floor, on your back, as you work the heads off. Ugh. Nightmare

Joel
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Old 02-26-2001, 11:08 AM   #10
ColinL
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Wimp. I figure 30 minutes per cylinder head with 2 friends helping is way easier than yanking the engine.

And no, I haven't yanked the engine yet to try it that way.
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Old 02-26-2001, 02:24 PM   #11
mcgyver
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Jason,

I remember you, white Legacy w/gold '98 track wheels.

Anyway, mines confirmed, [combustable gases] in the radiator. I went to a shop today and they put the sniffer in the radiator. [He said, yep it's toast]. so, it's going in this week to Santa Cruz Subaru for head gaskets. It should fall under the Powertrain Warranty 5yr/60k.

I went to my shop and realized that I have a portable gas detector that I use for Natural Gas leaks. I tried it on my car and it Works. So, I'll bring it to the next Track Day to test people's cars if they suspect bad head gaskets.

Adam
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Old 02-26-2001, 02:28 PM   #12
WRX1
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Also, check for tiny air bubbles in the radiator. If the head gasket is going (or gone), you will have bubbles in the radiator (the worse the gasket, the biggier the bubbles). Also you could go to a mechanic and they have a special dye (sorry, can't remember the name), but they can test for co2 is the anti-freeze.
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Old 02-26-2001, 03:20 PM   #13
SteveS
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Colin ~~ I agree with Joel. Take the engine out, or at least lift it past the fenders in the bay. Working with RalliSpec, my engine was pulled in about an hour and a half. No fuss, no muss.

Steve __'Mr. O-ring'
http://www.lagging.com/

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Old 02-26-2001, 05:35 PM   #14
bratmantlz
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Question

so are these 98's with high mileage? has this been a common occurance with 98's or just a few??
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Old 02-26-2001, 07:13 PM   #15
mcgyver
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High mileage, No

I've got 41k

This didn't just start, it's been going on for many months. I remember that it Overheated once at the last Track Day back in September. It's been happening more often lately, though.

At Track Day the Overflow would fill up and actually overflow itself. You could watch the bubbles rise in the resevoir, [combustable gases] The engine was pressurising the cooling system and pushing-out the coolant, so it would take awhile to get HOT.

And, he doesn't have to pull the engine, it's probably still under warranty.

Adam

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