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overheating 99 outback


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14 replies to this topic

#1 Todd C

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Posted 03 October 2003 - 11:03 AM

Hi: Just found this forum, I've been looking for something like this for a while and since my 99 legacy OB has 116k on it now this may be very helpful. Anyway I've been dealing with an intermittant oveheat problem for some months now and I cant figure it out... the car will run normal for weeks at a time and then all of a sudden the temp gage will peg. let it sit and cool down and will run fine again for quite a while. I've replaced the coolant and thermostat (subaru thermo). coolant level doesnt seem to change. no bubbles in the coolant while running. hoses are new. I have also seen it peg the temp gage and by the time I notice it the gage starts to drop to normal. within 15-30 seconds its back to normal -
What am I missing??? any suggestions appreciated
Todd :cornfuzz:

#2 Dinero

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Posted 03 October 2003 - 11:26 AM

Hmmmm......2.5L DOHC. Unfortunately, I would have to suspect problems with the head gaskets. Have the coolant ckecked for combustion gases. With the 2.5L DOHC, the head gasket failure allows the exhaust gases to force the coolant out of the engine block. Have it checked NOW, because a fairly large number of posters on this board have suffered warped heads and even total engine loss as the result of this problem.

#3 cookie

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Posted 03 October 2003 - 11:28 AM

That sounds like a head gasket, but from what I have seen here
and what happened to mine the phase two usually has exterior leaks.
I would run a test on the coolant to see if it contains exhaust gases.
I have seen other causes for this type of behavior in other brands but Subarus have weak head gaskets on the 2.5s.
Around here you can go to an auto parts dealer and get a kit to test your water.
I would do this very soon as you may avoid a warped head.

#4 1 Lucky Texan

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Posted 03 October 2003 - 11:33 AM

Todd C didn't mention confirming proper operation of the fan. Is there any correlation between idling/stopping and the temp creeping up? If so, the fan may nnot be working and you're only getting enough air through the radiatoor while moving.

just a thought

Carl
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#5 cookie

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Posted 03 October 2003 - 11:50 AM

would be the next items I would check but it sounds like head gasket behavior.
When you get a gas bubble the temp will go up and come back down relitively quickly.
I have had leaking head gaskets drive me nuts back before the testing kits were available.
There are two vehicles in my past that I never really found out why they would over heat. I must have checked the head and deck of one Ford 390 five times and the thing would still leak under certain temps and loads. The other was a Fiat.
One vehicle I found a piece of a thermostat that would circle around and block the water intake only when it felt like it.
One time we found a new water pump had been delivered and installed with no impellor.
Check the water, it's easy.

#6 Commuter

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Posted 03 October 2003 - 12:08 PM

99 Legacy Outback will be the Phase I 2.5L DOHC engine which usually suffers from "internal" headgasket leaks as described.

Been there.. :(

Is there any sludge in the coolant expansion tank? The combustion gases percolating thru the coolant will cause an oilly looking sludge. And the bubbles as mentioned.

Is it only happening under "load"? That is, highway driving, towing, going up a hill, hauling lots of people or stuff? Sometimes the leak won't even appear until the engine is stressed. I've heard of people driving around town for weeks with everything seeming to be fine (after a t-stat or whatever) and then one day they hit the highway and BAM, the overheating reappears.

In my own personal ordeal, I never once saw the temperature gauge budge. I first noticed the sludge in the coolant. Once driven, the tank would rise to a high level and bubbles would start showing up. Mine never overflowed, but that happens to people as well when the leak is of sufficient size.

Commuter

#7 Todd C

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Posted 03 October 2003 - 12:11 PM

Thanks for the quick replies... Whenever I have the overheat both fans are running, forgot to mention that. I have NO signs of external leaks at all. I have seen it happen under load and at idle. Haven't seen anything unusual in the coolant, though it has been drained and refilled probably three times in the past year. I have had this car since new and its been used hard at times, but taken care of.
I dont like the idea of doing head gaskets, not sure I'm up to that (sounds like a lot of work, but I'm too cheap to pay someone to do something I can do myself :-\ ) I guess I'll get a kit to test for gasses in the coolant and take it from there. I think I will also pull the radiator and try to flush it and the engine with a hose to make sure there's nothing in there that shouldn't be...
Todd

#8 cookie

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Posted 03 October 2003 - 12:22 PM

then this makes perfect sense as this is phase 1 head gasket behavior.
Since my forester is a 99 with a phase 2 I assumed the outback would have been so fitted.

#9 Todd C

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Posted 03 October 2003 - 12:53 PM

Excuse the question, but, what is Phase 1 and Phase 2?

Commuter: I reread your post (should have read more carefully first time) and that sounds like my problem - the driving around for weeks at a time with everything looking fine. I assume it leaks slowly until you build up enough gasses in the coolant to cause a problem...
How bad is it to do head gaskets??? :(

#10 cookie

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Posted 03 October 2003 - 12:59 PM

more complex. Phase ones had quite a repution for head gasket failure in the painful manner you are experienceing.
The phase two is single overhead cam and has a rep for bing better about head gasket failure, but Emily at CCNC (do I have the initials right?) says more of them are coming in for head gaskets now that they are getting a few miles.
The real problem to me seems to stem from the fact that they overbored this engine and left the top of the deck open.
I have the latest gasket in my phase two and I am hoping for the best.
On yours if it is a phase one the gaskets have been redesigned several time to try to fix this problem.
Make sure you get the latest revision. You won't get this at the corner autoparts store.

#11 cookie

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Posted 03 October 2003 - 01:05 PM

The other skip just did a gasket job on one of these and has his how to posted there and a lot of other good info.

#12 theotherskip

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Posted 03 October 2003 - 04:47 PM

as cookie mentioned, i wrote a site with lots of info about the head gasket failures, a diy repair, etc. you can visit it here. there is also a guestbook you can sign, and it starting to get a list together of people who have had failures. feel free to include it in any correspondence with subaru.

when i was researching, i found on a bwm site an explanation of the random overheating. you can search the archives for the exact quote, but it went something like this. after long drives, a lot of exhaust gas tends to get pushed into the cooling system. when you shut off the car, it will turn back into a gas and collect around the heads. as the car cools, the thermostat closes. when it heats up again, there is not gas surrounding the head, and it doesn't absorb heat like coolant, and it doesn't open the thermostat. it will super heat (sometime you can see the system boiling over), then finally heat the surrounding coolant enough to open the thermostat, then the car cools back down. it can send you down the wrong path thinking that the thermostat needs replacing when in it actually is working fine.

hope this helps...

#13 cookie

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Posted 03 October 2003 - 07:01 PM

I was taught in a course years ago. the way t was explained to me was that you tend to get three stages of heating in an engine.
Stage one would be you general dirve around town where it does not get that hot.
This car would be fine for that. My wife's dad had a mini in New Zealand he drove for several years like that. He just filled it every day. I could not stand it and changed the head gasket, but that is beside the point.
The second is a longer trip.This is where your car falls down.
What we were told is that all componants come up to full operating heat and pressure.
In this case exaust gas leaks past the gasket and replaces the water in the thermostat area and above. The engine then boils for a second and the water moves around and opens the thermostat stopping the boiling. This sounds pretty much like the other explanation. when this happens there would be a discharge of pressure from the radiator cap.
A limp home fix would be to pull the thermostat.
Third stage heating would be a cross country trip when everything gets as hot as it can and this is where the big failures begin. Trust me on the last one as I spent ten years running busses NY to SF.

#14 1 Lucky Texan

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Posted 03 October 2003 - 10:40 PM

Wonder why the coolant had been changed 3 times in the last year? Was 'special' care taken to 'burp' the system when refilling? Are there 'cool' areas in the radiator?

Carl
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#15 Todd C

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Posted 05 October 2003 - 09:04 PM

Refilling three times may be an exaggeration, I may have lost count. I have drained and refilled at least twice since last winter. Both times to change the thermostat because of the overheating. Both times it seemed fine for quite a while afterwards. Anyway, I think I am going to drive it once or twice to work this week while attemting to see whats going on. I haven't payed much attention to what came out of the radiator when it heated up in the past. I will now see if there are gas bubbles when it heats up. I expect there will be. I will also check into the combustion gas tests.
I expect that I will be doing head gaskets in the near future. I have checked your site 'theotherskip' and it will be very helpful. I will sign in if/when I know for sure about the head gaskets.
Thanks for all the help...
Todd




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