This overheating needs to stop....... It stopped!!

[httrdd]

I cannot figure it out for the life of me! :smt011 I can run all day on the highway and as soon as I get off it overheats. I was thinking air flow problem, but the drivers side fan is running. Is the passenger side fan supposed to be running when the temp are too high or is that just for a/c? I am soo confused!

[Huffer]

Sounds like your radiator is partially blocked, or your thermostat is busted. Highway speed = better cooling. Last time I checked both fans are supposed to come on when you're idling...

I'd get a new thermostat first - it's a cheap part, much cheaper than fans.

[httrdd]

Just changed out t-stat last week with oem one so it cannot be that. So our fans are both supposed to run at idle? Hmm good to know. That explains why that fan does not come on with the a/c. Is there seperate relays/fuses per fan?

[Huffer]

Well if you just changed out your t-stat, you'd have had to refill the coolant? So you might have an air bubble. Try burping the system.

[httrdd]

I flushed and burped two or three times each. I am familiar on what to do with the heating system I just need to figure out what is going on here!

[StatGSR]

Id also make sure your radiator is clean. its amazing how much dirt and nastiness can clog them up and destroy the efficiency.

compressed air probably works the best. still kinda hard with it still in the car though.

[httrdd]

Now when I get going normal driving it starts to cool down. I am puzzled.

[rougeben83]

only 1 fan kicks in when mine idles...I think the pass one kicks in when you have the ac on @ idle.

[mike-tracy]

If OEM t-stat, then it's gotta be a blockage or bubble. When I ran my car w/o a t-stat it would actually go below the normal temp line. Previous owner had used stop leak in my radiator, and that probably caused the HG's to blow due to overheating (in my EJ22)

[StatGSR]

Now when I get going normal driving it starts to cool down. I am puzzled.

why?????, there is more airflow across the radiator at highway speeds.......

[httrdd]

I meant after the overheating at a stop it will start to cool down when I get going and air flow is there. It does not always happen to me everytime I get off of the highway though! It is just random! I just wish it would break so I can fix whatever is wrong already!

Now can anyone else confirm that we have one fan that runs for cooling and the other for the a/c?

[Huffer]

Either way, something is up with your radiator, or t-stat. That's the only reason your temp gauge drops at higher speeds, because of the ambient air wicking heat from the engine. When you are stationary the engine has no way of cooling itself because the coolant isn't cycling around. My guess is your t-stat is bad or installed incorrectly, or you have a blocked radiator or a huge air bubble....based on previous experience.

[httrdd]

Thanks Huffer I am going to drain the system and check the radiator again. I am actually going to physically pull it out and inspect this weekend. I have tried to burp the system numerious amount of times. Do you recomend running the engine with the cap loose to burp the system or will that just squirt coolant? I installed the t-stat the same way it cam out and it is a new one so I dunno. I just need to figure this out so I can keep modding!

[Huffer]

Pull the t-stat and test it in a pot of boiling water... it is supposed to open at a certain temp. If it's bad/won't open take it back and get a replacement.

I ran the engine on ramps, cap off and squeezed the hoses a bunch of times...sometimes the bubbles are finicky, especially if you rushed the refill...pour slowly. To test the radiator you can just pull hoses off both ends and shoot water through it - it should drain really quickly.

GL - it's damn fustrating!

[StatGSR]

when u pull the radiator be sure to clean it. and i mean the outside of it, through the fins, not the inside.

[httrdd]

On my way to the highway the temp came up as I was going down a steep hill. I am going to blead the radiator running today at work and see if that makes a difference.

[SOREN]

Just a quick note - cooling issues are really annoying. I don't actually have my Legacy yet, it's on it's way.. but I do have 3 other subies - all imprezas' though. My STi is currently experiencing cooling issues. I drove without any heat in the car for the last 2 weeks, thinking that my issue was a heater core or something, only to get heat when I hit 3000 RPM+ but idling the air was freezing (up in Edmonton, Canada). Found out that one of the main issues was indeed an air bubble. Opened the rad cap, and ran it for about 15 minutes, and was getting heat in the car again. One of my buddies' WRX's took an hour and a half with the rad cap off, running to get the bubbles out. I've now found that I do indeed have a leak, but I'm not sure where -it's in the front hoses somewhere, but I can't see it. Possible rad cap too - I'll buy another one straightaway and see if that helps.

All to say to the OP, yes. Remove the rad cap and let it run for a long time. At least 10 minutes. I'd hazard a guess that you could be looking at a bad thermostat.

This is a good thread that deals with cooling issues. Everything You Ever Needed To Know About Cooling Systems
http://www.rs25.com/forums/f190/t40373- ... stems.html (http://www.rs25.com/forums/f190/t40373-everything-you-ever-needed-know-about-cooling-systems.html)

Good luck, and please post the resolution when you get 'er figured out so you can take the puzzle out for someone else!

[httrdd]

Wow and hour and a half! :shock: I think that is my next step today then. Hopefully this gets the cooling system back to normal. If it was a block in the radiator it would happen most of the time unless it was something moving around. It has to be bubbles, cause when I go down or uphill at slower speeds the needle climbs. I will let you all know the results. Thanks guys! :smt023

Great link btw!!!!!

[httrdd]

WOW! There was a lot of bubbles coming out! Some bubbles came out as I started running it, but after it got to normal operating temps it was really bubbling and I kept squeezing the upper hose. At idle I am back where I used to be just under the half way temp mark. As I rev the engine the temp drops. Is that normal? The heat is blasting out again on full. I am going to do this again tomorrow before work to see if I can get anymore bubbles out. I am going to push my car tonight like I used to and see if it holds up.

Thanks for the great info guys! TJ

[iampetro]

i wanna know if it held up?

[httrdd]

Day 2 pushing the car and yes it did! The original problem was the t-stat (tested the old one) and after that the stubborn air. My heat comes on now in a matter of mins while warming up. It is performing better then when I got it!! Thanks for the info guys! You all really saved my a lot of money and time I could of wasted! Now I feel like a total newb!

[Huffer]

^^ glad it worked out. :)