I have a97 Legacy Sedan 2.5GT with 90,000 miles and have been having overheating problems for about 6 months. I have taken the car to my mechanic (one that I've used and trusted for 15 years) and explained that the overheating only happens when I reach a steep hill (like the one to my house) after driving with no problems on straight roads for long distances. I had driven over 200 miles in 100+ degree heat with the AC on with no problem, but as soon as I reach the hill to my house the temperature guage would peg in about 3 seconds and start spewing fluid by the time I hit my driveway. The thermostat was changed about three times to no avail. The mechanics had done multiple tests to diagnose the problem, but nothing showed. I then took the Subie to the nearest Subaru Dealer/Service center and they performed diagnostic tests and found nothing also (they didn't even charge me). The manager had suggested that it might be the heads or head gaskets, because he had seen one other case like this. I took the car back to my mechanic and after the heads were done , it now overheats more frequently, usually after highway driving. I've since had the radiator, water pump, the thermostat was replaced again and the fans are on when the car overheats. I like my Subaru and would like to do whatever it takes to get this car running to use as a backup for a new Subaru (I put lots of milage on and would like my new car warranty to last). Any help or insights would be appreciated.

 

The Mechanics lifted the front end of the car on the hydrolic lift while in idle. No overheating. It only seems like it overheats when the car is under a load. The coolant hoses have all been replaced.
Thanks

 

There seem to be 2-3 issues with soob engines that can, under the right circumstances, lead to overheating,loss of coolant-type problems. Even worse, you can have more than one problem - like headgaste leakage - the will lead to further overlapping symptoms.

Let's start with a couple of issues that seem unique to soobs. Most newer soobs have, (IIRC - can ayone confirm?) a 'reverse flow' radiator. Coolant comes in to the bottmo and flows out (back to the engine) from the top. One issue with this is, if you ever let the overflow get empty, when the engine cools off, it will suck air into the rad., then, when driving after the t'stat opens, a bubble could be forced into the engine from the rad. Any place it hangs out is not being well cooled, will overheat, probably causing a local steam explosion or at least more gas expandsion, forcing coolant into the over flow - maybe under a lot of pressure.
Also, in some models, evidently the heater core is mounted high enough, in relation to the engine, tha air can be trapped there too. I also just read of a guy that incorrectly did a TB bypass causing a high spot that collected air, causing coolant problems.
What all this means is , it can be tricky to really confirm ALL the air is out of the coolant system.
My advice is to start with the best, known (so far) methaods of confriming minimum air entrapment in the system before assuming you have bad h'gasets.
Put the A/C system in full heat, put the front of the car on ramps-steeper the better- some folks use the curb or a steep drive way. make sure you have the o'flow tank full(even a little more than max - you will need to monitor it closely). Remove the rad. cap and open the bleeder on the other side of the rad. if equipped(anybody know which models have this for sure?) Make sure the rad is full til fluid comes out the bleeder. Start engine and run till t'stat opens and fan cycles a couple times. Check coolant level in rad. if low top it up, close bleeder, replace rad. cap. Let engine cool. Monitor o'flow tank for change in level. Open rad. cap and confirm rad is full. Add coolant if necessary to rad and o'flow tank. Start and run engine to op. temp. again, let cool, watch for lower o'flow tank level, top up if necessary.

back car off ramps and drive normally BUT monitor o'flow tank for normal levels.

If during above tests you see CONTINUOS bubbling in rad. or oily resdue in coolant you have bad h'gaskets.

If after doing the above you still have overheating problems, an exhaust gas test must be done in the coolant. Also, the sending unit could be bad/intermittent. A mechanic could confirm the engine is actually too hot.

let us know

Carl
1 Lucky Texan

 

?does the coolant system build pressure?
if not try to replace the rad cap the cool system is designed to operate under pressure, no pressure no operate.
does the system loose coolant under normal operating conditions? do you have to add coolant after a long level cruise?

 

I took the Soobie to yet another mechanic. He purged the coolant system of air (he said it was tricky and took almost 2 hrs) and I tried it again. I got 2 and 1/2 days of driving before it spilled its guts again. I brought it back and they found (I think they said) carbons in the coolant, which indicates the heads or much worse, a crack in the block (if the heads were tested and replaced properly the first time). I am now looking at replacing the block with a used or re-built if the heads check out OK again. Oh well, I'll check back in later. Thanks all.

 

Its your head gaskets. I've been thru it...Trust me when I say to replace them. Exact same symptoms as mine when they went out.

Chris