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1999 Outback Overheating Mysteriously


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I have been having overheating issues with my 99 Outback. I took it to a local shop and they have been unable to find anything wrong with it. The overheating happens sporadically. I have been reading alot about head gasket leaks. Are there any definitive symptoms of a head gasket leak???

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the symptoms. Sorry to joke about it but these are pretty hard to find when they start.

Do a seach on this board and you will see the trials and tribulations of others. A combustion gas test won't always show positive, compression tests only show when they are really bad, and a leakdown test does not always work because they seal when they are cooler.

Do all the usual things like radiator cap, thermostat,(Subaru brand only), check water pump, hoses, radiator, etc. Bleed the air out carefully and hope.

If you are at the point where a gunky residue shows up in the overflow tank it is prestty certain. If it were my car I would change the gaskets for PM reasons at this point to prevent problems even if they were fine.

Finally if all else fails change the gaskets with Subaru's latest version.

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the symptoms. Sorry to joke about it but these are pretty hard to find when they start.

Do a seach on this board and you will see the trials and tribulations of others. A combustion gas test won't always show positive, compression tests only show when they are really bad, and a leakdown test does not always work because they seal when they are cooler.

Do all the usual things like radiator cap, thermostat,(Subaru brand only), check water pump, hoses, radiator, etc. Bleed the air out carefully and hope.

If you are at the point where a gunky residue shows up in the overflow tank it is prestty certain. If it were my car I would change the gaskets for PM reasons at this point to prevent problems even if they were fine.

Finally if all else fails change the gaskets with Subaru's latest version.

 

Do you know anything about the conditioner that Subaru uses in vehicles that have a recall for this issue?

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The earlier cars (phase 1 engine) are not helped by the conditioner. I have a phase 2. The phase 1s (which yours should be) usually leak into the combustion chamber. Phase 2s get a small external leak which the conditioner can stop. This was a bit late for me as I had already changed the gaskets by the time Subaru came up with the conditioner.

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I'm pretty sure that you have the infamous Phase I DOHC 2.5L engine. If so, the conditioner is not for your engine, nor will it do you any good at all. Chances are that you have an internal head gasket leak. You might want to have the coolant checked for exhaust gases. Monitor this condition closely, as you do not want to cause damage to your engine through overheating.

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I'm pretty sure that you have the infamous Phase I DOHC 2.5L engine. If so, the conditioner is not for your engine, nor will it do you any good at all. Chances are that you have an internal head gasket leak. You might want to have the coolant checked for exhaust gases. Monitor this condition closely, as you do not want to cause damage to your engine through overheating.

How do you check the coolant for exhaust gases? Is this something that has to be done at the dealership?

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To find if you have antifreeze in your oil, the easiest method is to have a used oil sample analysis done. To do this you will need to go to the blackstone.com website and ask them to send you a sample bottle. It's free and takes a few days to arrive. You will then need to get a sample of engine oil out of your crankcase and into the little plastic bottle. It only takes a few ounces. The testing costs $20 with postage about $1.50. Depending on the mail transit time, you will have results in a few days, by email if you want.

 

They include a short description of the results and comments. What you are looking for is antifreeze. If you have water it will be easily seen because very much turns the oil into an ugly colored pudding. Antifreeze shows up as high amount of potasium and/or sodium in the list of elements in the oil you will get from Blackstone. They will usually identify even small amounts of 10 ppm as suspected contamination. The other numbers serve as a measure of oil condition and engine wear.

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If you want to check for residues in your cooling system - take the radiator cap off and have a look at the water in the resovoir! If there is a scum on the surface of the water, or it smells fuelly or is greasy between your fingers then there is a leak! It may not be this obvious though!

 

Also check for bubbles rising in the resocoir when the engine is running - denotes gasses being forced into the cooling system through a leaky head gasket. Also check the pressure of the radiator inlet hose - it shouldnt be rigid, if it is it denotes the system is pressurising and this may be affecting water flow, and contributing to the overheating. All these point to the same thing, a blown headgasket!

 

Im not completely familiar with the subi engines yet, but im just going through this same scenario with an old BMW atm! Head gasket leak, scum in water and overheating sporadically! Have just started a chemi-weld treatment to seal the leak for the short-term, and get some more life from the engine. But this is an old engine on a fairly valueless car, so it will do the job for a while! Im not recommending this on the Outback! I stuffed around with thermos, radiator cleaning etc etc etc... and this was the result! Just thought id share!

 

Good luck!

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What ~Outback~01 said.

 

Also, check the level of coolant in the overflow tank. Is it near the top? Does it not go down as the car cools? Is it not a nice clear green color? Yes indicates leaky HG, which is the default diagnosis for your engine.

 

I don't think you need to worry about antifreeze in the oil, and don't get sucked into replacing every cooling system part before the HGs are finally done. It just adds to the misery.

 

Good luck.

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Many people with 2.5 DOHC will initially see overheating only after an extended run, usually at highway speed. It's normally a slow leak of combustion gasses into the coolant, not coolant into the combustion chamber. Oil contamination is not normally present, with a simple headgasket problem. Prices for the repair if needed are normally less with an experienced local mechanic than the dealer, but all Subaru parts should be used in any case. Someone here may be able to recommend a good service location if they know where you live.

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