Coolant lost after autox?

[nyfries]

So few month ago I check my coolant level for the first time since I got the car. Is it right at the low line when cold but expands up I somewhere between high and low when warm up. I thought nothing of it. At that point I have autox the car about 3 times.

Level stay stable this entire time


Yestedday I went autox again and today when I check the coolant level is way pass low when cold and just above low when hot.


Not smelling or seeing any coolant leak. So I feel like its overheating thus burning coolant?

How can I prevent this from happening or this is just the cost of racing? Could it just be evaporation of water inside the coolant due to extreme engine heat? In that case should I just add more water to it? If not what kind of coolant can I use to too up? Subaru super blue coolant is way too expensive from the stealer shop. Can I just use regular blue coolant? 50/50 mix with water or just pour it straight in?

Has this happen to anyone else that drive their car hard or do any kind of HPDE?

[Sportsguy83]

Coolant loss is no good news. Might be a sign of problems to come.....

Get the Subaru coolant. $25 a gallon is not bad for coolant, and it's not like you will use it up quickly.

[nyfries]

Originally Posted by Sportsguy83

Coolant loss is no good news. Might be a sign of problems to come.....

Get the Subaru coolant. $25 a gallon is not bad for coolant, and it's not like you will use it up quickly.

The thing is coolant level stay the same in daily driving it is once I push it and drive it hard at an event that this happens?

[Sportsguy83]

Originally Posted by nyfries

The thing is coolant level stay the same in daily driving it is once I push it and drive it hard at an event that this happens?

Coolant does not evaporate unless you take your coolant temp to red and at that point engine damage is the concern. It is weird for a stock car to be loosing coolant.

[nyfries]

Just to clarify im looking at the coolant reservoir. Did some search on this forum and notice a lot of ppl is noticing this? Anybody else with this problem can chime in? In any case I will book an appointment with the dealership. I doubt they will do anything more than topping up the fluid.... I'm just worry that there might be bigger problem like sportsguy83 said. What should I look for?

[texasbound972]

Happened several times to me. The first time I took it in to the dealership. They didn't find any leaks except for the cam plate. They didn't have any idea why it was low. My guess as well with other socal86ers is that the coolant is evaporating through the small hole on top of the plastic reservoir. So for now I always keep Subaru coolant in the garage.

[nyfries]

Originally Posted by texasbound972

Happened several times to me. The first time I took it in to the dealership. They didn't find any leaks except for the cam plate. They didn't have any idea why it was low. My guess as well with other socal86ers is that the coolant is evaporating through the small hole on top of the plastic reservoir. So for now I always keep Subaru coolant in the garage.

Is there any function to the small hole? If coolant is indeed evaporating there why does that hole exist. Seem like a huge oversight on behave of Subaru/ toyota.
And I thought the cam plate only leaks oil?

[ZOMFGAARON]

I have 10,100 miles on my car, it's been serviced twice in that time, and I've noticed my coolant is low as well. I've never tracked my car but it is my dd. I'm taking it to get looked at Friday. If I cover up the small whole would it cause any issues?

[phrosty]

I noticed coolant well past low about a year after I got the car. Plenty of "spirited" driving but no autox, and stock other than an intake. Filled it back up between the markers, good to go.

It's been over a year since I did that, and I've not had any apparent coolant loss since. No clue what it was. It's my understanding that coolant should not evaporate or need replacing for an extremely long time so it's a bit puzzling, but apparently not an uncommon experience with this car.

[Euro7R]

Mines between high and low mark. Apparently that's supposed to be normal? I daily my car and sometimes rip it hard here and there.

[DarkSunrise]

I notice a very slow loss in coolant over time. My guess is either:

1) The small hole in the overflow tank allows water to evaporate slowly

2) The FULL line is actually a hot line, and if you fill to full while cold, you're actually overfilling it.

I keep my eye on it, but not too worried at the moment. I don't notice any correlation to track days, so that's probably a good sign.

[Sportsguy83]

Originally Posted by nyfries

Just to clarify im looking at the coolant reservoir. Did some search on this forum and notice a lot of ppl is noticing this? Anybody else with this problem can chime in? In any case I will book an appointment with the dealership. I doubt they will do anything more than topping up the fluid.... I'm just worry that there might be bigger problem like sportsguy83 said. What should I look for?

I think you should not be too concerned. Cars can consume coolant. The problem is it can keep getting worse until its a bad headgasket, but keep it in perspective and that is very rare to happen.

Originally Posted by nyfries

Is there any function to the small hole? If coolant is indeed evaporating there why does that hole exist. Seem like a huge oversight on behave of Subaru/ toyota.
And I thought the cam plate only leaks oil?

The small hole is there for safety. If someone overfills the reservoir (meaning anything over the "fill" line, the hole provides an escape for the extra fluid when the car is hot and it has expanded. Fluid does not evaporate through there. Fluid in the reservoir is not at evaporation temperature.

Yes, the cam plate only leaks oil.

Originally Posted by Euro7R

Mines between high and low mark. Apparently that's supposed to be normal? I daily my car and sometimes rip it hard here and there.

Take a look at it with the car cold. If its in between when the car is cold, then its good.

Originally Posted by DarkSunrise

I notice a very slow loss in coolant over time. My guess is either:

1) The small hole in the overflow tank allows water to evaporate slowly

2) The FULL line is actually a hot line, and if you fill to full while cold, you're actually overfilling it.

I keep my eye on it, but not too worried at the moment. I don't notice any correlation to track days, so that's probably a good sign.

#2 is correct.

[nyfries]

So should I just fill it up with a little Subaru coolant? Do I have to mix it with water before topping up or the coolant is alrwady premix

[Fastbrew]

When filling with Subaru supercoolant - you only need to fill to the bottom line. That's enough coolant. That is how they ship as well.