Loss of Coolant - Subaru Outback - Subaru Outback Forums
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post #1 of 8 (permalink) Old 12-19-2011, 05:37 PM Thread Starter
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Loss of Coolant

My 2000 Outback seems to burn through coolant at a very fast pace. It never overheats but it'll empty a full coolant reservoir in about 3 weeks with just daily commuting.

Any thoughts of what might be causing this issue?


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post #2 of 8 (permalink) Old 12-19-2011, 07:49 PM
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A leak?

But seriously, how long has this been happening? Are there any other symptoms? Is there any evidence of oil in the coolant? Pull off the oil fill cap and see if there is a frothy mess, if so there may be coolant in the oil. In either case, you may have a bad head-gasket which is a common issue on MY2000 cars. Are you using the recommended Subaru coolant?

Coolant leaks can pop up in colder weather as rubber seals contract and get brittle and the leaks don't always happen when in the driveway, It may only leak when the car is up to operating temperature on the highway. Check the thermostat connections and coolant hoses for any perforations. Squeeze all the hoses (while they are cold) and ensure all hose clamps are tight.

There is lots of generic non-Subaru specific guidance on diagnosing coolant leaks on the interwebs...

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post #3 of 8 (permalink) Old 12-19-2011, 09:05 PM
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YOu may have a cracked radiator and never know it. They fluid can leak out and you never see a puddle. Get the system pressure tested to start.
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post #4 of 8 (permalink) Old 12-21-2011, 02:02 AM
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It might be a cracked radiator, a worn out radiator hose, lines to and from the IACV, etc etc. A pressure leak down test usually can find out there. Worst case: head gaskets

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post #5 of 8 (permalink) Old 12-21-2011, 08:24 AM
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crawling under the car should reveal the headgasket leak if it has one as they leak externally. your car was originally covered under a 100,000 mile extended headgasket warranty by Subaru, that's probably the most common scenario but let's hope for something simple.

this engine requires a Subaru Coolant Conditioner ($2.47 at Subaru last I bought it). this means a two things for you:

1. if it is leaking at the headgaskets - use two bottles of this conditioner immediately and it might stop it.

2. if it's not the headgaskets you need to get the leaked fixed and add this conditioner as most of it is probably gone with the "long term coolant flush" that's happening by adding coolant every now and again.

it's loosing coolant and has to be going somewhere. have you tried looking around/under the vehicle?

how long have you owned the car?
has it been driving perfectly fine for 3 years and then this started?

if there's a leak there's really no way to narrow it down on the internet, just need to simply look, the fluid is going somewhere and that much will have signs in the engine compartment somewhere. there are a lot of places they can leak and none are much more common than any other, except unfortunately external head gasket leaks on this engine:

radiator cap, headgaskets, lower radiator hose, upper radiator hose, thermostat housing, heater core return hose, heater core supply hose, radiator leaking side tank, throttle body return hose, throttle body supply hose.

there's a lot of hoses and clamps - if any are rusted, have been worked on before or the rubber is dry rotted - they all have a good chance of leaking.

H6 OBW VDC, H6 OB Sedan, Tribeca, Lifted XT6
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post #6 of 8 (permalink) Old 12-22-2011, 03:59 PM Thread Starter
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Thanks for the replies on this so far. I have checked under the car for any leaks or to see if coolant has been on any other parts, the only leak my car has right now is a small oil leak. I can't find any cracks in the hoses or rusty connectors or anything that looks like it might be the source of a loss of fluid. The engine never seems to run too hot, but could there be a chance of it running a little too hot and burning through the coolant quicker than normal?
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post #7 of 8 (permalink) Old 12-22-2011, 05:20 PM
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Your normal operating temp should be 170 degrees F. This puts the needle about 1/16" below center. Under normal operating conditions, it will amaze you how rock steady it will remain there. The wife's '97 is awaiting an en route water pump. It leaked at such a minuscule rate that it didn't 'mark its spot' during the warmer weather. Now it will leak at the rate of one drop/sec., but only when under neutral pressure (especially with the cap [Stant] off for checking/filling). The only indication at other times is the dry milky trail on the lower radiator hose. We check it every other day (car averages less than 15 mi./day). It has 183K on the 'meter, but I love boxers (hoarded Corvairs) & intend to keep it serviceable +. Make certain that you don't have glycol based antifreeze leaking into the crankcase! I swear that it will cause the the Babbitt layer on bearings so constructed to slough off, increasing the shaft to bearing clearances by an order of 300% or more. That translates to swift death with knocky accompaniment!!!
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post #8 of 8 (permalink) Old 12-27-2011, 06:45 AM
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Originally Posted by SoulsurferOR View Post
My 2000 Outback seems to burn through coolant at a very fast pace. It never overheats but it'll empty a full coolant reservoir in about 3 weeks with just daily commuting.

Any thoughts of what might be causing this issue?

I am the tech manager at Prestone Antifreeze. Check out these service bulletins on your car regarding coolant loss

NUMBER: 08-52-08
DATE: 08/18/08
1999MY and later Impreza & Forester
2000MY and later Legacy & Outback
2006MY and later Tribeca
SUBJECT: Coolant Overflow
If you encounter a vehicle which experiences coolant coming out of the coolant reservoir tank, it may be caused by the radiator cap pressure valve being stuck open by debris sucked up through the reservoir tank hose. As the cooling system cools down, it sucks coolant back into the radiator. If there is debris that settles to the bottom of the reservoir tank, the hose is low enough to also suck them back into radiator. This causes the radiator cap not to seal, allowing excessive amount of coolant to escape overflowing the reservoir tank. If this condition continues over time, there will not be enough coolant in the system to maintain proper engine temperature.
In order to correct the condition you need to clean (and test) or replace the radiator cap, clean out the reservoir tank, and shorten the hose slightly, following the repair procedure.
Production Line Change

The shorter coolant reservoir tank hose was used in production as shown above.
Repair Procedure/Information
1.Radiator Cap Cleaning
Many caps can be successfully cleaned. The important part is the thorough cleaning of the negative pressure valve. If this is not done completely, remaining debris may result in a repeat issue. If there is an excessive amount of debris or the sealing rubber on the cap appears to be pitted or damaged, replace the cap.
Note: If replacing the cap, skip to Step 2.

Using clean water and a brush, thoroughly clean the cap seal surface.
Note: A used toothbrush which has been cleaned works great.

Manually open the negative pressure valve. Using clean water and a brush, thoroughly clean the valve (inner and outer surface) and the valve seal surface.
Check the radiator cap valve opening pressure using a radiator cap tester to insure the cap is within specification (refer to the applicable Subaru Service Manual).
Note: If the cap is out of specification replace it.
2.Coolant Reservoir Tank Cleaning

Remove the reservoir tank (refer to the applicable Subaru Service Manual).
Using clean water, thoroughly clean the inside of the reservoir tank.
Reinstall reservoir tank. Fill with coolant to the Full mark.
Note: Be sure to use genuine Subaru Super Coolant or Subaru Long Life Coolant, depending upon what type of coolant is currently in the system.
3.Coolant Reservoir Tank Hose Modification

Remove the hose from the reservoir tank. Cut 20 mm from the bottom of the hose at a 45°angle. Reinstall hose in reservoir tank.
Start engine and permit to fully warm up.
Turn off engine and allow to fully cool down.
Recheck coolant level in reservoir and add coolant if needed.
Note: Be sure to use genuine Subaru Super Coolant or Subaru Long Life Coolant, depending upon what type of coolant is currently in the system.

Warranty/Claim Information

© 2011 ALLDATA LLC. All rights reserved.Terms of Use
NUMBER: 09-42-05
DATE: 04/15/05
All Models
Cautions Concerning Engine Coolant
The purpose of this bulletin is to inform of cautions concerning engine coolant.
When adding, replacing or servicing the cooling system always use Genuine Subaru Long Life Coolant. Genuine Subaru Long Life Coolant is a phosphate (non-amine) type and is specially formated for all Subaru vehicles equipped with aluminum engines and radiators. Coolant of other types may not provide the proper protection to aid against corrosion of aluminum parts. If an equivalent must be used, make sure it is a phosphate (non-amine) type. As a reminder, use of Genuine Subaru Long Life Coolant is mandatory on all repairs paid for by Subaru of America, Inc, that require the replenishment of coolant. This holds true for any claim type.
Do not use flushing machines.

If a flushing machine has been used to service other brand vehicles with copper radiators, a chemical reaction between copper ions and Subaru coolant may occur. This could also cause clogging of the radiator.
If regular flushing is required, only use fresh tap water. Do not use hard water. Hard water will create calcium build-up which will clog the radiator.
Whenever the coolant is changed, you must add Genuine Subaru Cooling System Conditioner. Genuine Subaru Cooling System Conditioner has been tested and approved for aluminum engines and radiators.
Do not use after-market coolant reinforcement agents, sealers and/or flushing agents as those chemicals could corrode aluminum parts.

And last, the cylinder head issue-
DATE: 02/2004
2000-2002MY Subaru Legacy and Outback;
1999-2002MY Impreza; 1999-2002MY Forester
Engine Cooling System Conditioner
Subaru of America, Inc. (SOA) has determined that over time, affected vehicles may develop small external coolant leaks at engine cylinder head gaskets. This is the result of normal expansion and contraction of engine components caused by the heating and cooling of these parts. To prevent cylinder head gasket leaks from developing or to correct existing leaks, a special Subaru Cooling System Conditioner should be added to affected vehicle cooling systems.
This Service Program will involve adding one bottle of Genuine Subaru Cooling System Conditioner to the engine cooling system.
2000-2002 MY Subaru Legacy and Outback with 2.5L engine.
1999-2002 MY Impreza with 2.5L engine.
1999-2002 MY Forester with 2.5L engine.
Affected vehicles are identified in the VIN range chart below. Only vehicles with a 2.5L engine are affected.
NOTE :Prior to performing repairs, confirm coverage for potentially affected vehicles by using the Vehicle Coverage Inquiry in the Dealer Communication System (DCS).

Vehicles identified in the preceding chart may include VINs that were not distributed in the U.S. market. Dealers will be provided a list of VINs that include the owner name and address. This information will enable dealers follow-up with owners of potentially affected vehicles. These listings contain owners names and addresses obtained from State Motor Vehicle Registration Records. The use of such motor vehicle registration data for any other purpose is unlawful. Accordingly dealers are urged to limit the use of this listing only for the purpose of completion of this service program.
SOA prepare and mail an Owner Notification Letter to owners of the affected vehicles. Because of the number of vehicles affected and parts availability, owner notification will occur on or about the dates listed in the following four stages.
1999 MY - February 16, 2004
2000 MY - March 1, 2004
2001 MY - April 1, 2004
2002 MY - May 3, 2004
A copy of the owner notification letter is included at the end of this bulletin.
Owners are being advised in the owner notification letter, found at the end of this bulletin, that if they have previously paid an authorized Subaru dealer for repairs related to this Service Program, they may be entitled to reimbursement. The owners are further advised, to qualify for any reimbursement they must submit the original repair invoice to Subaru of America, Inc. Please review the owner notification letter, which explains this procedure so that you are familiar with it, and can assist owners with any questions.
In the future, it will be necessary to add Genuine Subaru Coding System Conditioner to the coding system of affected vehicles whenever the engine coolant is replaced. As a reminder, owners will be sent update pages with their notification letter that instructs them to add the pages to their Owner's Manual and Warranty and Maintenance Booklet Except for the initial application associated with this campaign, the cost of adding the conditioner is the owner's responsibility.
For owners of affected vehicles that have this Service Program performed promptly, SOA is extending coverage under the Subaru Limited Warranty for cylinder head gasket external coolant leaks to a period of 8 years or 100,000 miles, whichever occurs first Warranty coverage begins on the date the vehicle was delivered to the first retail purchaser. If the vehicle was used as a demonstrator or company vehicle before being sold at retail, warranty coverage begins on the date the vehicle was first placed in such service.
As a further condition for this extended warranty coverage to apply, the owner must properly maintain the vehicle's cooling system in accordance with the recommended maintenance schedule and Genuine Subaru Cooling System Conditioner must be added each time the engine coolant is replaced. Resulting damage caused by a lack of maintenance or low coolant level will not be covered. Replacement of the Cooling System Conditioner during inspection and maintenance services is not covered under warranty.
Dealers are to promptly service vehicles subject to this Service Program at no charge to the vehicle owner regardless of mileage, age of the vehicle, or ownership.
For affected vehicles sold after the date on the dealer's computer list, dealers are to contact those owners and provide them with a copy of the owner notification letter. They should also arrange to make the required correction according to the instructions in the service procedure section of this bulletin.

Vehicles in Dealer Inventory
Dealers are also to promptly perform the applicable service procedures defined in this bulletin to correct affected vehicles in their inventory (new, used, demo). Additionally, whenever a vehicle subject to this Service Program is taken into dealer new or used inventory, or is in the dealership for service, necessary steps should be taken to ensure the Service Program correction has been made before selling or releasing the vehicle.
New or used vehicles listed in a recall/campaign that are in dealer stock must be:
^Immediately identified.
^Tagged or otherwise marked to prevent their delivery or use prior to inspection and/or repair.
^Inspected and/or repaired in accordance with instructions outlined in the Product Campaign Bulletin.
Any Authorized Subaru Dealer failing to perform the applicable service procedures defined in this bulletin to correct affected vehicles in their inventory (new, used, demo) prior to the vehicle being placed in service may be in breach of the Subaru Dealer Agreement.
Subaru Cooling System Conditioner
Note :Subaru Cooling System Conditioner is packaged in cases that contain 12 bottles. Each affected vehicle requires one (1) bottle. Each case contains enough material to treat 12 vehicles.
Prior to the release of this Service Program, each dealer will automatically be shipped a quantity of Subaru Cooling System Conditioner equivalent to 40% of their vehicle sales, or up to a maximum of 20 cases.
Additional quantities of the Cooling System Conditioner will be available through normal parts channels after 2/15/04. In order to maintain an adequate part supply, SOA requests that Dealers only order quantities necessary to satisfy anticipated demand.
The repair procedure involves adding Subaru Cooling System Conditioner to the cooling system. Follow the recommended procedure that applies to either a "Cold" or "Hot" engine.
Caution :The engine cooling system is under pressure and may he extremely hot. To prevent personal injury or vehicle damage he sure to take appropriate precautions while performing this procedure.
Service Procedure on a COLD Engine
NOTE :Impreza and Forester vehicle system components are shown in the images below, but Legacy and Outback models are similar. Consult your service manual for exact locations and illustrations.

1.Install rags around the radiator filler neck to prevent coolant from contaminating the engine area.

2.Take off the radiator cap and set aside.

3.Extract 125ml (4.23 oz.) of coolant from the radiator using a suitable device such as a piston syringe, meat or poultry baster, antifreeze hydrometer, etc.

4.Place the syringe into the overflow reservoir and push the coolant out of the syringe.
5.Shake the bottle of cooling system conditioner until all contents are thoroughly mixed.
6.Pour the entire bottle of cooling system conditioner into the radiator.
NOTE o NOT pour the cooling system conditioner into the overflow reservoir. The conditioner Will settle at the bottom of the reservoir and not mix in the cooling system.
7.Reinstall the original radiator cap.
8.Remove rags from around the radiator filler neck.
9.Start the vehicle and let it run until the engine is warm. This ensures the conditioner circulates and there are no air pockets in the cooling system.
Service Procedure on a HOT Engine
1.Turn the ignition key to the "ON" position (engine off).
2.Turn the air conditioning "ON" to cycle the cooling fans. Leave the air conditioning "ON" for approximately two (2) minutes. This will lower the pressure in the cooling system.
NOTE :The pressure relief on a "HOT" engine is approximate. Caution should always be taken when removing the radiator cap on a "HOT" engine. Additional A/C "ON" time may be required to relieve cooling system pressure properly.
3.Turn off the air conditioning.
4.Return the ignition key to the LOCK ("OFF") position.
5.Follow procedure for COLD engine listed above.

Type or print the necessary information on a Recall Campaign identification label. The completed label should be attached to the vehicle's upper radiator support.
Credit for performing this Service Campaign will be based on the submission of properly completed repair order information. Dealers may enter the applicable claim information through their Dealer Communications System.
Listed below is claim entry information:
Add Engine Cooling System Conditioner - Use the following information for claim submission:

Enter labor operation 122-801 for 0.2 labor hours.

Enter the applicable part number. Parts will be reimbursed at dealer cost plus applicable handling allowance.


Hope this info helps, you can email me with any cooling system questions at jay.buckley@framgrp.com
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