Strange cooling system issue under certain conditions: 97 OBW

[v8volvo]

Dealing with some odd cooling system symptoms on a 1997 Outback. This car has been in the family since 2003 but my folks drive it so I don't have much chance to pay attention to it. Took it in to do some work to it yesterday and on the way home it did some weird stuff.

 

The problem occurred after I idled down a long hill in traffic on a cold evening with the heater on full hot, blower fan on "2" and engine fully warm. We were inching down the hill, trans in neutral (5-speed). When we got to the bottom, I noticed the heater was blowing cool air. Soon after that, the temp gauge began to wander upward. Pulled off the road, shut down (didn't let it get hot) and checked fluids. All full and clean. Started back up and drove home with no further issues -- temp stayed normal.

 

When we were safely home, I decided to go for another spin and try to replicate the problem again. In order to get it to act up, you have to do a few certain things: heater on full blast, fan all the way up, engine warm, and IDLING. If you let it sit and do this for 5 minutes, the air eventually gets cold, and then the temp starts to climb. But if you raise the revs at any point, the cycle resets and the heater gets toasty again and no temp spike.

 

I know the Subaru thermostat/heater circuit is a funky (read: stupid!) design. I'm in the middle of swapping an EJ22 into a Vanagon and we have taken steps to avoid the thermostat issues in that setup by installing a bypass circuit that prevents cold air from the heater return hose from making the thermostat close on a warm engine. Here is my theory: with engine idling, coolant is not pumped fast enough through the heater circuit to prevent the heater core from being cooled by outside air being blown over it. Then the return to the thermostat becomes cold too, and makes the t-stat close. If you rev it up, a flood of hot coolant enters the heater core, heats it up, heats the thermostat up, and everything stays happy.

 

Am I way off on this? Shoot me down if I'm missing something.

 

I know these engines are notorious for headgasket problems. My folks bought it at 33k and it now has 95k on it. Still pretty young and a great runner. I would hate to see them have to go through a HG ordeal. Wondering if these are symptoms people see in cars that *don't* have headgasket issues or if it is a clear HG problem. The car got a new thermostat, water pump, and timing belt 15k ago.

 

Last thing: when you turn it off, there is a gurgle from the heater core. Air in the system, sounds like. But from where? It wasn't there before. Telltalte head gasket failure?

 

Apologize for the ignorant questions, I spend all day working on diesels which act very differently when they lose a HG. These Subies are a different animal and I am not as familiar with their ways and tendencies.

Edited January 29, 2010 by v8volvo

[nipper]

Actually subaru t-stat and cooling design is not funky. It is only funky when you put it in a car it was not designed for (like a vanagon).

 

You have what may be a bad head gasket, but first I want you to replace the radiator cap and see if that clears it up. Next I would replace the thermostat with one from OE only. Aftermarket chokes the coolant flow.

 

you can be getting air in the systme from a faulty radiator cap, or from a faulth head gasket.

 

Let me know what happens.

 

 

nipper

[Blacky]

Sounds like classic head gasket symptoms to me also. Sad to say.

[Rooster2]

"Last thing: when you turn it off, there is a gurgle from the heater core. Air in the system, sounds like. But from where? It wasn't there before. Telltale head gasket failure?"

 

Sad to say, the air in the cooling system, is the classic symptom of a bad HG. The "air" is actually exhaust gas escaping into the cooling system from combustion chambers through the bad HG. It is that hot air that causes the engine to over heat, while at the same time, impeding the flow of water/antifreeze through the heater core, causing the heater to blow cold air. When this is happening, you will prolly see air bubbles in the radiator over flow container. The air bubbles is/are the exhaust gas escaping from the cooling system.

[nipper]

sheesh everyone is such a pesamist in the morning

 

 

Dont go tearing into it right away if it is a HG, the car is under 100K for the extended warrenty, but over the age for it. Maybe we can get subaru to help out on the cost of repair.

 

nipper

[Fairtax4me]

"Air" in the system from a failed HG will be in the form of exhaust gases. Doing a simple block test will reveal if this is HG related.

[subaruplatt]

1

Edited January 30, 2010 by subaruplatt

[subaruplatt]

The internal low friction nature of the subaru engine is cool idling.

So yes that is what a subaru does it cools off rapidly.

Why you are overheating under these circumstances,I can't say.

I can feel the loss of heat imediately when I sit idling, I have to turn up the heat.

 

Sounds like you did everything you could think of to chill the engine.

 

This might open up head gasket leaks I don't know?

Try same test only this time leave it in 2nd or even first gear but not in neutral.

 

Why people don't avail themselves to engine braking I don't know.

[idosubaru]

This isn't strange, sounds very normal.

 

All obvious cooling system items that are fundamental to all other cars should be checked. But it's a likely head gasket, sounds like classic symptoms to me.

 

You don't even have a hard one - mechanics get really confused when they pass compression tests and early ones can even pass hydrocarbon tests - those give mechanics migraines. $1,000 later and they still don't have it fixed .

 

The extended 100,000 mile headgasket warranty mentioned is only applicable to 2000-2002 models. Occasionally there's situations where Subaru dealers or regional folks have assisted with head gasket repairs, so it's a worth a shot.

 

EJ25 headgaskets are covered like nuts on here and all over the internet, so everything you'll need or want to know is easily available.

[v8volvo]

Many thanks for all the help. Brought it in to the shop today so I could take a better look at it with some night..... Well, the news is pretty ugly. Classic HG failure. The expansion tank has a coating of black scuzz on the inside of it, coolant is dark and cruddy, bubbles coming out of the overflow hose all the time when running. I stuck my nose into the overflow tank and the stink nearly knocked me on my back. Like sticking my face into a bucket of gasoline. I'm spoiled by working on biodiesel cars all day that smell nice. Gassers really stink.

 

In any case, all the signs are pointing to one thing...... hard to avoid the unfortunate conclusion.

 

What a cruddy design. I'm bummed, I knew this motor was a ticking time bomb but I thought it might at least make it to 100k. I'm just finishing up building the car that is going to replace it and we were getting ready to sell it. Dang. I guess I will be doing gaskets in it. Or better/cheaper to swap in an EJ22?

 

My folks also have an 06 OBW with 85k on it now, bought it at 73k last year. Wondering about its HGs now too. Seems like these engines are just fragile. Nothing like my beloved Volvo Turbodiesels.....

 

So the question now is, what route do we take from here? Dump the '97 cheap with blown headgaskets as a project for someone else? Replace the gaskets and sell it? Drop in an EJ22 and sell it? Or replace the gaskets or engine then keep the '97 and sell the '06? The reason they bought the '06 is they need AWD in the winter but were getting worried about the '97 blowing its gaskets, which has now happened. However if I go ahead and fix the '97 it will be reliable again, and maybe the '06 engine will still be a question mark. Is a properly repaired EJ25 P1 or an older EJ22 a better bet than a new EJ25? We all hate the way the 2006 handles, feels very unstable, and the shift strategy of the transmission is horrible. The old '97 steers much better so if the drivetrain could be relied upon that seems like the nicer car to me...

 

Any opinions? Thanks again for all the help.

Edited January 30, 2010 by v8volvo

[idosubaru]

Properly repaired, the EJ25 head gaskets are not likely to have problems. Personally I would never drive a 1996-1999 EJ25 vehicle unless they've already been replaced, for that reason.

 

The 97 verses 06 just comes down to personal preference and money, that's it. The 97 can be a very reliable car and is likely to make another 100,000-200,000 miles with a few repairs along the way - a wheel bearing, alternator, knock sensor, etc. Not likely to have anything major if it's maintained well. The 06 isn't likely to have things like that go wrong with it.

 

06's are not known for head gasket issues. Subaru is well aware of the head gasket issue in that motor and has taken significant steps throughout the 2000's to address it. My guess is they should have it fixed by now.

[subaruplatt]

In your final questions you brought up several issues. I am currently driving an 06 impreza wagon and I find it handles extremely well. I find that careful attention to tire pressure is all that is necessary. Too much is as bad as too little. Personally I go for the factory 33/30 in the winter with my snow tires and in the sumer with the stock brigstones I go 35/32.

Maybe there are alignment issues with yours?

Recently I had the firmware re flashed and that seemed to cure the transmission from hunting. It has smoothed out the car and has perked up the throttle response. (even my wife noticed)

In regard to the 97 It would seem that you were lucky to find out about the head gaskets before any permanent damage was done and that the fix should be good.