Subaru overheating


Asked by May 20, 2015 at 11:42 AM about the 1999 Subaru Legacy 4 Dr Outback AWD Wagon

Question type: Maintenance & Repair

About 4 weeks ago my 99 Subaru Legacy Outback started overheating and at the same
time I lost all heat inside the car.  It just blew cold air.  I took it to the mechanic.  They said
that the bottom part of the radiator had a lot of frozen antifreeze in it.  They thawed it out,
put in a new thermostat, refilled the coolant, ran it for a couple of hours, driving it around,
etc and it didn't replicate.  Exactly 1 week later it did it again.  They couldn't relplicate at
the shop, so they put on a new radiator cap and again refilled the coolant and this time
the oil as well.  They were thinking that maybe the coolant didn't fully thaw last time, and
possibly the cap was failing some.  Yesterday I noticed it was starting to run hot again,
but for now I still have heat in the car.  I did put some coolant into the radiator, but its still
hot.  I'll check it again tomorrow to see if it needs more, I'm not sure if I put enough in
since the car is on a hill in the driveway.  There was a lot of bubbling when I put it in.  The
headgaskets and stuff were all replaced by the dealership just before I bought it a couple
of years ago.  The car has just shy of 100,000 miles on it.  It had not done this prior to the
antifreeze freezing.  Any thoughts?

19 Answers


If the engine is running radiator cap off is there a lot of bubbling?

7 of 7 people found this helpful.

Hmmm, I'll check that tomorrow after it stops snowing. If it is, what might that mean? Oh, the mechanics said they couldn't see any leaks anywhere.

1 of 1 people found this helpful.

I am wondering if simply flushing the system would fix it?

1 of 1 people found this helpful.

It would be a good idea but 1st check when the car is cold take radiator cap off top it off with water and start it is if there is a lot of bubbling

6 of 6 people found this helpful.

I will try that. What might that mean?


You mentioned bubbling on the radiator we need to make sure is not a blown head gasket, We just need to make sure the next step is to flush it I will tell you how

5 of 5 people found this helpful.

I think it was bubbling because the fluid was low. I filled it while the car was turned off.

1 of 1 people found this helpful.

Oh OK Then I sugest to flush it

2 of 2 people found this helpful.

I forgot that we have a really good shop in town that specializes in cooling systems. I'll set up an appointment there. Hopefully the third time will fix it for good.


If the coolant was partially frozen the first things to do would be thaw it out, flush it out, and add the proper mixture of antifreeze/ water to the cooling system. Since you lost heat it sounds like you were very low on coolant. That being said the coolant has to be going somewhere. HTH. -Jim

1 of 1 people found this helpful.

I had it towed to the garage today. They found a very small crack in the upper part of the radiator in the plastic piece that connects to the hose. Since the crack was in the radiator, technically, they replaced the whole radiator. They (and I) feel that the crack and leak were due to the initial freezing of the antifreeze in the old radiator. Hopefully this does the trick.

2 of 2 people found this helpful.

Thanks for the update, Amanda. Continue to monitor the coolant level and watch for leaks. Since the coolant froze the possibility exists that one of the freeze plugs popped as well. When coolant freezes it expands. In order to prevent the block from cracking freeze plugs are installed and designed to "pop" . If this happens they must be replaced or they'll leak. HTH. -Jim

3 of 3 people found this helpful.

Thanks for that tip Jim, I will keep an eye on it.

1 of 1 people found this helpful.

You're welcome. Glad to help. -Jim


You have probably got an airlock in your heater element. This mimics all the symptoms of a head gasket leak. Water has to flow through the heater element to bypass the thermostat and make it open up...See my full explanation and solution here: -

16 of 16 people found this helpful.

I have a 1998 subaru forester and its over heating

3 of 3 people found this helpful.

I have a 1998 subaru forester and its over heating can i get some help

3 of 3 people found this helpful.

I have a question about a 2000 legacy it's overheating the air conditioner get colder than crap when you turn it off the car over heard when you take the radiator cap off with the car running it gushes back out any suggestions on what might be wrong

4 of 4 people found this helpful.

Venrick,Anthony_60, I tell you that I am learning a few things about this engine, the one thing I will share that is relevant to all this is that after replacing the timing belt, water pump, guide wheels and tensioner I had a hell of a time getting the air out of the heater core, I couldn't figure out why the damn thing was overheating( the car as well as me), the clue was no heat......always keep the heater on and blowing when checking the cooling system, very important !!! You will overheat with a quickness with an air locked heater core. After filling the system, block, core and radiator, each one separate, I still had air lock....... I had to let it warm up, a little I might add cause you don't want to end up in the burn ward, and burp the air by pulling the return hose off of the core. What a pain in the ass !

1 of 1 people found this helpful.

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