99 legacy outback overheating

[BobJ]

Here's the deal my wifes legacy outback temp would go up and down I changed the therostat, it didn't help. I changed the coolent temp sensor no help. I have bled the air out of the cooling system no good, changed the water pump, while in there new timing belt. It runs great but going up hill under a load it overheats. put it in neutral bring up rpm's a little it cools down. I have also flushed the system.

[cal_look_zero]

You could have an issue with your fans operating properly or perhaps your radiator fins are blocked up by dirt and crud, but your more likely suspect is:

 

Head gaskets!

 

Sorry to say it. Combustion gases leaking into the water jackets causes overheating under load. Fortunately you're catching it early, probably before any real damage has been done.

 

Fortunately there's a lot of USMBers up your way who can help you figure out exactly what it is, and maybe even help you fix it.

[idosubaru]

when it runs hot are the fans coming on?

 

clogged radiator (radiatorbarn.com has them for under $100 usually shipped to your door - $88 for last EJ rad i bought).

 

or headgaskets are failing. these are usually completely random and not associated with loads, etc. it could be that you "think" it's load related though if it's just started and you've only a seen a couple anecdotal overheats. look to see if you have bubbles bubbling into your coolant overflow tank while running or right after you shut the car off. if you ever see that, it's pretty classic headgasket signs. there are also test kits for analyzing the coolant for exhaust gases to test for failed HG as well.

[BobJ]

Thanks for the input, my fans are working, and I have checked the radiator and it is clean. I just have to face it and change the head gaskets.

[the3rsss]

Repeating what has been said.....overflowing or high coolant level in bottle. Bubbles in bottle. Overheats at idle after a long drive. Smell coolant bottle, when my hg failed it was like sniffing the exhaust pipe. You can do a hydrocarbons test, but if you have these symptoms chances are your headgaskets are bad. Good luck.

[Rooster2]

Just gone through this over heating nonsense on my 98. Sorry to say that it is very likely your head gaskets. On mine, I hoped it wasn't, but it was the HGs.

 

Avoid further over heating cycles, as it is very hard on the engine. It is just too easy to warp aluminum engine components. Once warped from over heating, the engine will not be reliable.

[Ionlyhave3suubs]

Not sure if you are a do-it-yourselfer or not. Either way, make sure you only use the Subaru brand oem gaskets, make sure the heads are checked while off the engine to make sure the sealing surface is flat (a machine shop can do it relatively cheap if you aren't sure how), and after the job is done use a bottle of the subaru head gasket conditioner, it helps with the sealing. If you hire a shop to do the work for you insist on the above steps to ensure a good lasting headgasket seal. Cheaper aftermarket gaskets are prone to failure, or sometimes don't seal from the beginning. Oem parts are worth the money when doing a job that requires this much labor.

[idosubaru]

I have checked the radiator and it is clean..

a clean radiator doesn't rule out anything unless you completely disassembled i and checked the internals. they clog internally before external issues decrease cooling capacity to signficant levels.

 

I have also flushed the system.

radiator can still be clogged - i haven't been able to unclog two Subaru radiators by flushing - radiator replacement was necessary both times.

 

it sounds to me like you have bad headgaskets - it is common. *but* the one thing i see is that this is not a typical symptom of Phase I EJ25 headgasket failure:

 

It runs great but going up hill under a load it overheats.

 

Phase I EJ25's with *original headgaskets* (failure modes after replacement deviate) typically overheat randomly. that yours is 100% predictable leads to me to think it's worth making sure it's not something else. sounds like headgaskets, yes, but also sounds different enough that it's worth checking into.

 

if the headgaskets have already been replaced before or some previous owner dumped gobs of stop leak in it, then that changes everything.

[1-3-2-4]

Like others said it's the HG's I had the same symptoms.. It got really bad if you turned the AC on which caused extra heat from the condenser to be put on the radiator.

 

I got my parts ready like a month ahead before I did the pull (took a week) and after that it was done.

[mwbean]

try a leakdown test with a tester. if you are a DIY

you can find one here:

 

http://www.summitracing.com/search/Part-Type/Leakdown-Testers/?keyword=leak+down+tester&kr=leak+down+tester

[the3rsss]

I think the key is the bottle. If your bottle is overflowing or bubbling its either headgaskets or radiator. Cap. One or the other. the weak spot on the original headgasket is a small strip between the combustion chamber and the water jacket. Exhaust gas leaks into your coolant creating superhot pockets of exhaust. This causes your water pump to cavitate. Since these exhaust pockets are taking up space in your cooling system, they force coolant into the bottle. Sometimes the pockets make their way to the bottle in the form of bubbes. Lteakdown and compression tests might not show this. They leak somewhat randomly. But if your bottle overflows or bubbles, its a bad cap or headgaskets! Nothing else!