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Overheating 99 Legacy SUS...headgasket???


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Hello:

 

I just purchased a 99 Legacy SUS a few days ago...ran fine for a while, and yesterday, after driving for about 25 miles, I saw the temp gauge pegged to "HOT". I crank the internal heat to Max high, which blows hot for a while but then blows cold, and when I pulled over, the reserve tank is full. I filled the radiator after allowing it to cool, and drive a few miles with the same results.

 

Visually, the oil looks fine--not milky or anything. I don't notice anything unusual on the oil filler cap, and the exhaust isn't steaming. So...I'm hopeful that It's just a radiator cap or thermostat problem or something less expensive...

 

It's got the non-turbo 2.5L, and the car has about 142K miles on it. The engine runs fine otherwise, with good power.

 

TIA for any advise! The car's sitting at a gas station some 25 miles from home. Definitely not a place I'd have a major repair done on my car!!

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Hello:

 

I just purchased a 99 Legacy SUS a few days ago...ran fine for a while, and yesterday, after driving for about 25 miles, I saw the temp gauge pegged to "HOT". I crank the internal heat to Max high, which blows hot for a while but then blows cold, and when I pulled over, the reserve tank is full. I filled the radiator after allowing it to cool, and drive a few miles with the same results.

 

Visually, the oil looks fine--not milky or anything. I don't notice anything unusual on the oil filler cap, and the exhaust isn't steaming. So...I'm hopeful that It's just a radiator cap or thermostat problem or something less expensive...

 

It's got the non-turbo 2.5L, and the car has about 142K miles on it. The engine runs fine otherwise, with good power.

 

TIA for any advise! The car's sitting at a gas station some 25 miles from home. Definitely not a place I'd have a major repair done on my car!!

Welcome to the HG club.

 

Oils will look fine, Subaru 2.5 leak exhaust into the system. So the oil will never look milky.

If you just purchased the car, someone probably sold it because of the HG issues. It is not that bad, pay the $1200 to fix it and you are good for another 140k.

Sorry

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Hey thanks for the reply. Just an update for all:

 

The mechanic at the gas station removed the thermostat (didn't replace it, apparently), and filled the coolant. That did the trick (of course, I'd have to replace the thermostat, but at least it's not overheating...predictably, it runs too cool now). Just for a good measure, I invested $6 in a new radiator cap, just in case. So **Hopefully** I don't have a headgasket issue!

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Any oily looking sludge in the coolant expansion bottle?

 

Any bubbles coming up thru the coolant expansion bottle?

 

Note that you may only get the bubbles after a hard run.

 

Replace the thermostat with an OEM one. Make sure you put it in in the correct orientation if doing it yourself.

 

Do try the simple stuff first (t-stat, cap, etc) but keep a close eye on it. You are at prime age and milage for the dreaded headgasket issue.

 

Commuter

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but I think it has the begining of a blown head gasket.

The time to repair it is really now rather than after you damage something.

Sometimes that is not financially possible but don't go on a long holiday trip with this car.

I agree with cookie, all the signs point to HG failure.

The thermo removal will only help for a bit.

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Just throwing this out there, I don't know much about head gasket problems. I was thinking this could be a water pump going. The car would blow cold air if the pump was not working. Just my two cents worth.
Water pumps general leak before they go or make noises.

That could be but the 2.5s are infamous for HG issues, and all the issues point to that being the issue.

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Hmmm.

 

 

Doesn't sound too great...How long, generally, do I have till the HG absolutely needs replacing? I drive pretty gently, so hopefully that would prolong the life of HG..

 

Also, does anyone have experience with additives? Like the redline water-wetter, or SOA additive?

 

Hate to spend big bucks right before the holiday season....

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a bit. The water wetter might help a borderline overheating problem in Arizona, but you have a mechanical problem. The Subaru additive is for the next generation of engines that develop tiny external leaks, not internal.

You will have the combustion gasses venting to the cooling system under high pressure when it gets hot, and it will get worse and worse. Eventually it will become undriveable at all, and possibly damage the block and head.

Some folks have limped around town for a while with the thermostat out for a while till they could afford to fix it. The average non Subaru mechanic probaly can't even find it or diagnose it.

This would not be my choice as an ex mechanic. I would fix it or park it due to the extreme risk of damage.

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So when headgaskets are going "south", could that be a periodic problem? I drove the car about 45 miles today, and the engine ran pretty cool (cooler than regular operating temp). At lunch, I went out to a burger joint, and while I was in the drive thru, the temp went up to the normal operating temp and stayed there (I assume because the fan kicked in).

 

And if you guys could enlighten me...how are failing termostat and blown headgasket related? Does one cause the other?

 

TIA

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when the temp goes up from pulling hard or getting stuck in traffic. It might go weeks of short trip stuff without overheating again.

Taking out the thermostat lowers the temp the engine runs at. You don't really reach enough heat to make it leak. Check your water when the car cools down becuse odds are that was a bit of gas being released into the coolant at the drive in.

That is why it is so tough for a mechanic to find. By the time they go to test the engine it is cool and does not leak.It can release so little gas into the cooling system that it does not leave enough residue for a gas sniffer test to find.

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the head gasket failure is caused by poor design. Subaru has done at least three revisions to this gasket, and I have heard the latest seems to be working.

The thermostat probably did not fail at all. It is a good idea to change thermostats regularly since they work hard and are necessary for proper operation of the heater,engine cooling and fuel injection system.

Your engine will be running rich and affecting your mileage and emissions all the time you have it out.

On a car with a good design a bad thermostat can cause head gasket failure by an overheating event.In this case it is niether the thermostat's or your fault.

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The head gasket on my 1990 L went (2.2), to make a LONG story short, I took the thermostat out and drove it three years, (no heat in the winter), before the body rust forced me to part it out. The car was my daily beater, 210K with rust, did not want to put money in it.

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The head gasket on my 1990 L went (2.2), to make a LONG story short, I took the thermostat out and drove it three years, (no heat in the winter), before the body rust forced me to part it out. The car was my daily beater, 210K with rust, did not want to put money in it.
The 2.2 is a more bullet proof motor than the 2.5. If you do not fix the 2.5 then it will have bottom end issues. A 2.5 will not last last long wo issues.
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