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About a month ago the temperature would rise slightly and then fall right back to normal temp while sitting still in traffic (would happen everytime I was drivig). Had thermostat replaced (genuine subaru). Car has been working fine for a month now.

 

Just went for a roadtrip (15 hour drive), near the end of the trip after pulling off the highway and idling in traffic (or driving slower then 20km/.hr) the heat gauge would go up to the line under the red now, and it would stay there until the car started moving again, and then would drop right back down to normal temp.

 

I pulled over once while idling and the temp was high and their appeared to be coolant pooring out a bit from the top of the resovoir tank. I tested the system for air leaks and their doesn't appear to be any.

 

i'm thinking it might be a rad that's starting to plug up or another plug in a hose or something

 

The day this happened it was about 100 degress out.

 

Does anyone have any thoughts on what else to looks for

 

Drove the car a couple times since this happen (just around town) and it seems to run fine (although it's not as hot out now)

 

Heading home (another 15 hour drive) so hopefully this won't appear again.

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Whatever the problem is, I would definitely get it checked out and fixed asap. I would not drive it if it gets too near overheating. Overheating can damage the water pump seal, and on that engine, replacing the water pump is not going to be a pretty job.

 

When you saw coolant pouring into the overflow, was it blowing bubbles into the overflow at all?

 

If the thermostat was never replaced it might benefit from a new genuine Subaru thermostat at this point.

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I suggest you first have the coolant checked to see if there are any exhaust gases getting into it. If that checks out ok then I think you may need to replace the thermostat again. Also check the radiator for cool spots on it which would indicate the passages are plugged.

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Thermostat was replaced with genuine subaru one a month ago (has been running fine since then).

 

I assume coolant was bubbling (Although I didn't see it) just saw some dried coolant around the top of the resovoir cap and such the next morning when I looked)

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I noticed that the thermostat was replaced already but the new one may be defective. Did you check the coolant level after the incident happened to make sure it is full? If that is ok and there are no air pockets in the system then I would pursue what I stated earlier.

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New ones can fail though of course it isn't often. Like I stated earlier I suggest you have the coolant system checked for exhaust gases and if that is ok then make sure the radiator is ok. If that is ok then replace the thermostat.

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If the rad cap is gone, would I have had air in my system?

 

 

It depends, on where the hose is in the overflow tank. If it gets above the water line or runs out of water yes. If the cap has a poot seal then yes.

 

Do the simple and cheap things first.

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Have you seen a faulty new subaru thermostat before?
i saw it for the first time last week, brand new Subaru OEM.

 

if you're not loosing coolant then my guess is your radiator is clogged. unfortunately i just got done asking and there doesn't seem to be a definitive test. i tried a temp gun but that didn't work, too much heat generated and the temps fluctuate like crazy, every 1/16th of an inch reads different so hard to compare anything.

 

heat does bad things to oil, seals, and more - i'd fix this quick too.

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For a clog test i always used a hose. Same water that goes in should drian out. If it backs up in the tanks then it is not flowing right.

Also using the above method as long as the hose water is cold, you will feel ambiant temp spots if it is not flowing in some spots.

 

I will admit it is one of those things that can be a pita to test for, but it usually is those tests after everything else is ruled out.

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For a clog test i always used a hose. Same water that goes in should drian out. If it backs up in the tanks then it is not flowing right.
man where were you a couple weeks ago sneaky?! i did that test and that's what happened - not all that was going in was coming out, but i didn't know if that meant anything or not, a good bit was still coming out too so it wasn't obvious.

 

drove past NYC yesterday on my way to maine, thought about you nip!

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gauge would go up to the line under the red now, and it would stay there until the car started moving again, and then would drop right back down to normal temp.

 

That screams fans to me. When you're moving, you get airflow through the radiator, but when you're stopped it depends on the fans working to move air through the radiator. If the fans aren't working, it will overheat while stopped and be fine while moving.

 

Turn the A/C to max cold with it running, and take a look at the fans. Both should be running full speed.

 

The coolant out the overflow is normal if the engine is overheating.

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yea, double check the rad cap. iirc, the coolant system is a sealed system it operates under its own atmosphere. air in the system = bad mojo

 

I would also say it was the thermostat though. had this happen to me too.. brand new t-stat defective. also pay attention to the heat rating on it. Higher the heat level, the hotter the coolant needs to be before it opens.

 

was the system properly burped? and is there too much water in the system? bubbling water will cause air in the system bubbling and again = bad mojo

 

 

-Justin

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Thanks for all the suggestions. Both Fan's are coming on.

 

I managed to get the car home (another 15 hour drive) and it worked fine, ran at normal temp the whole way (It was a lot cooler outside on the way home). However I was in stop and go traffic and also a lot of hills and it still seemed okay.

 

I also forgot to mention I was noticing a wooshing noise coming from inside the dash when accelerating (like water moving).

 

Anyways I dropped the car off to my mechanic (Master subaru certified tech) who works at one of the dealers here. He's going to do a major checkover and hopefully will locate the issue.

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  • 2 weeks later...
Had a very small hole in the bottom of the rad that was causing the issue.

 

 

Just got the car back as had to wait for rad to arrive, + one of the coolant hoses had a very small leak as well.

 

My Subaru guy replaced Rad and one of the coolant Hoses, put on new clamps on all hoses, created a vacumm, filled up system and added subaru coolant conditioner.

Pressure tested the system overnight and it didn't lose any pressure. (Before rad/hose was replaced, was losing pressure overnight). He drove the car about 60-70 KM's) and it was working perfect. I picked the car up, was runnign great, no wooshing noise in dash anymore, and drove home about 120KM on the highway, when I got off the highway, heat gauge started to rise again, AT Oil temp started to flash (this never happened last time), Coolant Resovoir was full and a small bit came out the top, wooshing noise is now back in the dash and also when reving car up in park a small amount and then letting off throttle it would stall (Although he also just replaced battery cable ends so ECU is still in learning process).

 

Any thoughts? He said he did all the tests for a Head Gasket Issue, and it has no signs what so ever. He is a factory subaru Certified Master Tech.

Edited by dbullen
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