1999 SUS Legacy Overheating??

Drove to NC and back last 2 days. Had the oil changed on Monday. It was bout a 6 hour trip.

 

Car seemed to be temping fine until the last leg last night, up 77 and side roads that are hilly. Temperature Gauge was on H when I saw it but I was 1/4 from home, I coasted/gently used the gas to get it home.

 

Drove to work okay today (about 1.5 miles) although it was a little rough and smelled a like coolant. Just went out a cranked it up and it came to temperature normally and didn't seem to start to overheat again.

 

Should i be worried? I think I'll take it in tomorrow just to be safe.

Do a hydrocarbon test to see if the headgaskets are bad. Could also be a sticking thermostat.

Since these engine are very sensitive when it comes to its cooling system, you should never continue to drive the car when its anywhere past the halfway mark on the gauge. A few mins at that high of temps you could've done some bad damage meaning the headgaskets. Especially if they are the original ones. Get it checked out right away and if anything I would replace the t-stat with a Subaru part and get some fresh coolant in her. GL.

My 1999 Legacy Outback SUS is blowing straight cold air. The guy I bought it off of had taken the thermostat out and so I replaced the gasket and put the thermostat back in after I tested it (put in boiling water and see what happens...it reacted so I took that as it was alright). I just put in some head gasket sealant since I knew that was an issue when I bought it (call it naive but I thought that it wouldn't be that bad of a fix compared to the 1800+ needed for my cavalier to become roadworthy). I added all new coolant and now its pegged out at the top of the thermostat gauge. I know its throwing a code for an O2 sensor. Now when i even go a 1/4 mile its jumping up to reading Hot on the gauge. Whenever I vent the radiator it blows off a lot of steam but at least now its not bubbling throughout the coolant and the vent screw.

 

Currently it's blowing straight cold air even after I let the engine cool down a bit. I need help FAST! I really want to love being a Subaru owner but as a recent college grad cash is a little tight especially only working part time for the moment.

Did you "burp" it to get all the air out of the system? It worked for me so now I'll assume it works for you...

yea i ended up burping it and just have to keep checking the coolant levels. once i feel as if ive gotten all of the air out of the radiator (and enough water into the water pump) im gonna take it for a ride a little past 20 miles and see what happens...hopefully i dont end up stranded in pittsburgh

the gasket sealant will not help and it may do some clogging os don't add any more.

 

one of two things, either you have not filled and burped it correctly or you have bad head gaskets. REALLY bad head gaskets.

 

do a search for a thread titled, ''how to fill and burp your cooling system'' or the like. do an advanced search of just titles.

 

did you remove the vent plug when you filled it? if not then it has not been burped correctly.

 

did you fill it very very very slowly? if not is has not been burped correctly.

 

these cars are picky about the t-stat, and how they are filled with coolant.

 

but since the previous owner removed the T-stat because of overheating my guess is you have bad head gaskets.

 

ej25 engine 96 - 99 have a known issue with bad head gaskets.

i did all the recommended burping on mine and had no luck either. i finally gave up, killed the engine and was going to try again later when i noticed the coolant level dropped after i had turned the engine off. i kept adding as it dropped down, took about another half gallon that way. fired it up the next day after another top off and it ran beautifully. i havent had to add any to it since last june when i did that. weirdest thing i saw, it only worked with the engine warm and not running.

Remember when I said it worked for me? Yeah, it made it through 2 more hours of delivering and then back home with no problems so I figured I was fine. Yesterday I tested it and it overheated again... it's fine under normal conditions but about 2 hours into delivering it will overheat.

 

Today I took it to a radiator shop but we couldn't replicate it. It didn't even overheat when bypassing the radiator.

 

I'm down to a few theories:

-Didn't bleed it enough

-Water pump cavitation is causing air bubbles to form and be released into the system

-Transmission fluid is superheating the coolant

-slightly clogged heater core?

 

But actually I have no idea. Fans work properly, radiator, cap, and thermostat are all new subaru oem.

I am having the same issue. I have replaced the t-stat, water pump and got a new rad cap. I can drive 90+ miles on the highway just fine. It is when I get off the highway that it overheats. It then goes from a little too hot to back to normal when I stop. When I accelerate the car goes back up. I had it pressure tested for the head gaskets there is a small leak, but used blue devil on it and it worked just fine. Air conditioner and heat work just fine. I am right in the same spot. I have no idea what is going on with my SUS. I feel like these were the troubled cars in the subaru family. If anyone has any suggestions please let me know. I am at the very-confused side of things right now.

Your gaskets are most likely bad, but not very bad at this point. At highway speeds you're moving enough coolant at high enough wind speeds to cool any "super heated" coolant caused by leaking of the head gaskets. Acceleration puts more load on the engine than when at speed or a stop (this is also when the fans are running and RPM's are low).

 

Get a hydrocarbon test to find out for sure. Get it done and report back. No one seems to get one done and drags out the diagnostics and time.

 

OEM thermostats, OEM water pumps, and OEM radiators rarely fail. If the pump fails it's because it's too old, and if the radiator fails it's usually because plastic cracked (96/97 2.5 radiators, that is). Also, in my opinion, 98/99 radiators have too small of an internal capacity when compared to the 96/97 units.

Already had my mechanic do that. The hydrocarbon test came back inconclusive. Maybe I will just try blue devil again...Love this car, do not want to see it die anytime soon!

If blue devil is a coolant additive, you're better of not using it in the long run. Anything that gets added to the coolant can cause blockages and will be harmful over a long period of time.

 

Are you seeing any bubbling in the overflow reservoir at operating temp? Next time it start overheating, stop as soon as you can and look. Is there any gunk starting to build up inside? probably not bc the hydrocarbon test was inconclusive...

 

Now, when you say inconclusive, what does that mean? There are either hydrocarbons or there are not.

 

You should also make sure that all/any air is purged from the system. Air pockets will cause random heating unlike yours, but it's worth trying anyway. Plus, you could still have air in the system anyway.

There is some gunk that does show up in the reservoir. Figured that was normal. I also drove another 90+ miles on Friday and it didn't overheat. That was after I topped off the coolant and bled out all the air. It overheats sometimes and it frustrates me. I might just do the head gaskets if this keeps happening.

I'm having a similar issue but it's weird so I'd like to see what you guys think.

 

mine is an around town car, I hardly ever take it on the highway... only 116K miles. Replaced the t-stat and water pump when I did the timing belt at 100K.

 

I had to take the car on a road trip last week from Atlanta to Dallas and back. at about 3/4 of the ride out, I stopped to get some food and came back to a small amount of antifreeze on the ground and the overflow bucket was full. Started it up, watched the temp start to climb at idle. Just a little rev and the temp came back down to normal. I decided to continue since the temp stayed normal. the next morning I topped off the radiator with 50/50. No issues again until about 1/2 way back, I got stuck in bumper to bumper traffic. The gauge started to rise, I revved it a little and it came back down to normal and stayed there. No issues the rest of the trip.

 

The car runs fine, fuel economy is good and these are the only two incidents to report. Any thoughts?

Hello;

Are the cooling fans working? Around town you should be hearing them cycle on and off especially this time of year. Another good trick is to make sure all the dirt, dust, and bugs are blown out of the radiator and condensor. Good air flow equals cool car, Steven.