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2002 Outback LL Bean H6
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Discussion Starter · #1 ·
While heading home this afternoon, I noticed my temp gauge was at critical. I let it sit 3 times with the fans running to get home, about 5 miles. It would cool down, but got hot again after a mile or so. No steam or anything and the engine/cap didn't feel too hot to touch.

5 hours later: there are no puddles under the car, but I do see a tiny bit of coolant splash on the engine cover, near the overflow tank, and a very small amount on the driver's side fan, really nothing that looks like a leak. Hoses seem intact and not leaking.

I've had the car since late January and put about 2000 miles on it. I drive 23 miles to work and the gauge has stayed at the halfway point until today.

This weekend I changed both the serp belt pulley bearings with new ones. Could that have something to do with it? The car/belt appears to be running fine. There is a little chirp that I hoped was one of the bearings, but it did not go away.

The dealer I bought it from had the radiator, thermostat and cap replaced. Thermostat was part 48457, looks like a Stant XACT 170 degree from the search I did. Cardoc helped me determine my CEL PO420 code is from bad cats and I think he is right.

The overflow tank is full. When I turned on the heat limping home, the air did not seem very hot, but did get hot eventually. The gauge went back to the normal spot when cooled down.

Help! I can't afford to damage the engine, so I'll have to leave my wife and kids without her car.

Thanks in advance for any advice!!
 

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2002 L.L. Bean Outback H6 3.0
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76 Posts
I own the same car. Last fall my wife said it overheated. I replaced the coolant, cap and thermostat with Subaru parts and coolant. I have never had an aftermarket thermostat work in a Subaru. Another problem I had a few years ago is the little pipe that caries coolant to the nipple by the oil filter sprang a leak. It is a cheap part through Subaru, like $16. It is about a foot long or so, a metal pipe about 5/8" in diameter. I've noticed that the coolant can be low, but the recovery tank shows a normal level.
Reciently the lower radiator hose clamp leaked, causing intermittent overheating. Again, the coolant recovery tank was normal, but I added almost a gallon to the radiator.
 

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OBW H6 VDC, Tribeca, XT6
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12,385 Posts
Check coolant level immediately in the radiator, not the overflow tank. Overflow tank is almost meaningless sometimes, it's the radiator that matters.

If it's full then answer these questions, when it overheats:
1. are the fans coming on?
2. does it overheat while driving or at idle or both?
 

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06 OBW 2.5, 05 Forester, had 03 H6 OBW
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5,966 Posts
I own the same car. Last fall my wife said it overheated. I replaced the coolant, cap and thermostat with Subaru parts and coolant. I have never had an aftermarket thermostat work in a Subaru. Another problem I had a few years ago is the little pipe that caries coolant to the nipple by the oil filter sprang a leak. It is a cheap part through Subaru, like $16. It is about a foot long or so, a metal pipe about 5/8" in diameter. I've noticed that the coolant can be low, but the recovery tank shows a normal level.
Reciently the lower radiator hose clamp leaked, causing intermittent overheating. Again, the coolant recovery tank was normal, but I added almost a gallon to the radiator.
If that pipe rusted, the one that runs under the drivers side head is probably pretty rusty as well.

I replaced both, they looked really bad, and I'm sure soon I will get a leak in one of the ones under the intake manifold.
 

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Car: 2008 Tribeca, 2010 LGT, Sold: 2005 XT Limited
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If you aren't getting heat then either the thermostat is stuck closed, you have air in the system, or the water pump is totally shot. Probable air in the system, but you should also replace the thermostat with a OEM.
 

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2002 L.L. Bean Outback H6 3.0
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76 Posts
I replaced the metal pipe that goes under the head to the heater too. It too was rusty.
 

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2002 Outback LL Bean H6
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20 Posts
Discussion Starter · #7 ·
Thanks everyone for the replies.

This morning I was able to add almost a whole gallon of premixed (diluted) antifreeze, so I possibly have a slow leak that I didn't know about.

I drove the 23 miles to work and the gauge stayed where it had been at previously. Heat seemed to work fine also.

Looks like I'm going to change the fluid and thermostat this weekend and look for the source of my leak.
 

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01 Outback LL Bean
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2,454 Posts
Are there bubbles in the overflow when running? From your description I am 95% sure it is HG.

When the HG starts to leak it leaks exhaust gas into the coolant system. This pressurizes the system above the normal 15 psi and coolant is pushed out of the main system into the over flow along with exhaust gas bubbles.

Once enough coolant is pushed out of the main system the car will overheat due to lack of coolant.

The car can be driven, short distances, for a long time if you add coolant to the main system after your trip to replace the coolant that has been displaced in to the overflow.

Check for bubbles in the overflow. If bubbles are present then have a block leak detection test run.
 

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2002 L.L. Bean Outback H6 3.0
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This is an H6, not a 4 cylinder. Head gaskets are not an issue on the 6. Sounds like a slow leak somewhere. Check the metal pipes under the engine, hose clamps and the rad. cap.
 

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01 Outback LL Bean
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2,454 Posts
HG can be an issue on any engine. I have had the HG fail on my H6 at 165k miles. I replaced mine, and a few others on this board have replaced there's as well. The H6 does not have a HG defect like the Phase I EJ25 or Phase II EJ25 but I assure you that with enough miles and time any gasket on any engine can fail. Since the H6 was not introduced until 2001, we are just starting to see how these engines behave after 10-12 years and 150k+ miles of wear.

If the engine is overheating, not boiling over coolant, but the overflow resevoir is overfilled, that sounds like HG issue to me. Users needs to report if he also has bubbles in the overflow.
 

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01 Outback LL Bean
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The key to this diagnosis is that the coolant is being displaced into the overflow but the coolant is not boiling over. The only time this is likely to happen is if the coolant system is over pressurized due to an internal HG leak.

If the coolant loss was due to a slow leak then the overflow would most likely be empty because the engine would be taking coolant out of the overflow to replace the coolant lost in the main system as the leak continued. We have the reverse in this situation.

Nothing is definitive until the user reports if he or she has bubbles and a block leak test is performed though.
 

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06 OBW 2.5, 05 Forester, had 03 H6 OBW
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I have an '03 H6 with weepy head gaskets, just a trace of damp blue crunge in the center area next to the exhaust ports.

It's a bit drier after adding some subaru magic headgasket goop (Holt's RadWeld)
 

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2002 L.L. Bean Outback H6 3.0
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HG can be an issue on any engine. I have had the HG fail on my H6 at 165k miles. I replaced mine, and a few others on this board have replaced there's as well. The H6 does not have a HG defect like the Phase I EJ25 or Phase II EJ25 but I assure you that with enough miles and time any gasket on any engine can fail. Since the H6 was not introduced until 2001, we are just starting to see how these engines behave after 10-12 years and 150k+ miles of wear.
The H6 actually dates all the way back to 1987. It does not have a known head gasket problem. Ay engine CAN have a head gasket failure, but to immediately suspect the HG as an overheating issue is jumping the gun a bit. Generally, HGs don't just fail absent another underlying conditon. The chance of an H6 having a HG failure absent any underlining other conditions is quite small. If the engine is overheated or abused in some way then yes, the HG becomes more suspect.
I have an '01 with 165,000, and an '02 with over 200,000. I was suspect of the H6 when they first became avalable in the Outback. I did a lot of homework before I purchased the first one, and found them to be a very trouble free motor.
 

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01 Outback LL Bean
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The EZ30 was not available in the US until 2001 model year.

Comparing a ER27 or EG33 to a EZ30 is like (acutally worse) comparing a EJ22 to an EJ25.

In the EJ22 to EJ25 (which are both EJ motors by the way) comparison, there is a hands down difference in reliability, especially when considering HG longevity.

Also, I stated very clearly the reason for my diagnosis, which has little to do with the type of motor, but the symptoms the owner is experiencing. There are not many scenarios that will lead to a full coolant overflow while the main cooling system is empty.
 

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2001 Outback H6
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86 Posts
As the engine heats up and the fluid expands, it goes into the overflow tank. Then as the engine cools a vacuum is created and the fluid is pulled from the overflow tank and back into the cooling system.

Since the radiator was replaced, it is possible that the hose from the radiator to the overflow is loose, or cracked and is not allowing a vacuum to be developed. The fluid could simply be pushing out the overflow as the car heats up and not being drawn back in. The next time you drive the car and the engine is hot, check the coolant level in the overflow tank. Wait till the engine cools completely and check the level again. If the level remains the same, then the coolant is not being drawn back into the engine.
 

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2002 Outback LL Bean H6
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Discussion Starter · #16 ·
Well, I drove the car home from work and continued on to a store in traffic and the temp gauge stayed where it should. I didn't notice the new posts before I left work so I didn't check for bubbles or overflow level when hot.

I ran out and checked the overflow tank just now and the level appears to be the same as it was yesterday...about 2" from the top or so. There also seems to be a bit more coolant on the driver's side fan. I wouldn't call it wet, but there is some coolant in the crevices.

I'll try to monitor the overflow tank after my drive to work (ha, 7 hours from now, better get to sleep!) and post the results asap.

The Outback has 122800 miles on it. I had the local Subaru dealership do a presale inspection and they stated there were no signs of the hgs leaking. My wallet and I hope they were right, I already know I need new cats!!

Again, thanks for all the response.
 

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1993 Legacy LSi with still functioning Air Suspension, 1999 Outback 2.5L 5MT lab Rat
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I would solve the Overheat issue 1st. I would also use Subaru parts as and in addition to replacing the Thermostat, (very important) with a Subaru Part, I would also get a replacment Subaru radiator cap. I saw that someone posted Cooling system operation theory, but the key to proper operation, is in fact the Radiator cap. Sure a cracked recovery bottle (overflow) hose would not allow a vacuum but I have seen Subaru Cooling system conditioner, Bars leaks, KW seal, what ever your poison is plug/clog and ruin the radiator cap. Also if you do not have access to a pressure tester, maybe a trip to a reputable shop could save you in the long run trying to find a small leak.
On to the Catalytic Converters, excessive temperature in your engine could be givng you a false P0420 codes.
On that note a small leak in a head gasket running thru your engine and into your Catalysts will destroy them, Catalytic Convertors do not like coolant. This is where a pressure test can determine whether your suspected leak is external or internal.
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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I think the o'flow tank should only have about 2 inches in the BOTTOM. It's tricky to see, but there are cold full and hot full markings down low on the tank.
 

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2001 Outback H6
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Why a Subaru specific rad cap? I am certainly not arguing the requirement. My BMW 740i was very particular about certain parts. But a rad cap seems like a pretty simple item. Is it a pressure thing, or simply that experience tells you that aftermarkets ones are suspect?
 

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2002 Outback LL Bean H6
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20 Posts
Discussion Starter · #20 ·
Good morning!

I drove to work and again the temp gauge stayed where it should.

However, when I arrived I left the engine running and popped the hood....the overflow tank still has the same amount of fluid and I DID see little bubbles coming to the surface in the overflow tank. :mad:

Sooo....is that definitively a head gasket leak?

Would a radiator shop be the best place to take it for a leak test? I am not sure that I have found a reputable shop to work on the Suby yet! I have been doing everything myself so far.

Thanks for the help!
 
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