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Coolant boiling under T-stat? Most likely air...I know

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Hello all, I havent been around for the summer. Figured I would drop in and say hello with an issue.

 

Just re-sealed and fully serviced the GL-10 and noticed the heater wasnt working so well. I hooked up the heater core to a hose and flushed it both ways a bunch. Then I used one of those things that attach to the radiator to make it the highest point of the system. I proceded to bleed the crap out of the system. I got what seems to be all the air out of the system. I didnt use an oem T-stat ( I know I know) but using a hand held pyrometer, it is the same temp before and after the t-stat. My after market temp guage (mounted in the car) stays constant at temp and all seems just as it should.

 

Well after a few weeks I ended up parking in a very quiet area and noticed a faint bubbling coming from under the hood. After futher diagnosis, it seems to be coming from under the T-stat. Once the system is cool, I open the rad cap and the system is totally full, same with the over flow tank. I didnt have access to the rad burping adaptor, so I drove the front wheels up on some cinder blocks and burped it again. I didnt get a single bubble from the system? (I left it up on the cinder blocks to cool and it didnt bubble? WTF?)

 

I am going to go try it again, but being that there wasnt a single bubble that came out, I didnt change anything.

 

I am also wondering if since the out side tems are soo cold right now and my car will only warm up to about 180-182 and my t-stat is a 185. Is my problem caused by my t-stat being only partially open?

 

Mods.

-New napa brand T-stat 185deg (at warmest I can get the car is 180-182 deg with the ambient temps out side right now)

-water pump has 40k

-Most all gaskets new (cooling system doenst leak a drop)

-New dual core radiator

 

I did a search but came up with nothing.. Any ideas?

When I redid the t stat gasket on my RX (someone tried make-a-gasket instead :dead:) I reused the t stat I had even though it was an aftermarket, I had had the problem where it would take too long to open before, so i drilled 5 holes in the big side where the jiggler used to be, about 1/8" each, seems to work great for me.

-Bill

I believe you did not mention if the new therm. has a "jiggler" on it..if Not..that would be your problem providing everything else is working OK

There are a few ways this can happen. One way is to not slowly fill the cooling system while the car is running (allowing for the t-stat to open and keep filling, test dirve, repeat), or an improper T-stat. Another is air getting into the system somehow (bad rad cap, blown HG, Leak). I am fearing the middle one.

 

 

Replace the cap, refill the coolant system with the engine hot and running.

 

Good luck.

 

nipper

  • Author

It was snowing like crazy and I was under a 10x10 pop up tent when replacing the intake manifold and valve cover gaskets. When I dropped the new T-stat in. Im almost 100% sure it had a jiggler, I thought they all did? Come to think of it, I think it was gurgleing sometimes before (just not all the time). It only happened for a few mins and never gave me any trouble.

 

I dont lose any coolant, but I can hear the rad cap making funny noises. Sounds like its faulty.. It doesnt spit any out or suck any into the system? (When I did the full service, I fully cleaned the over flow tank and hoses)

 

Also- It is ONLY boiling under the t-stat and no where else in the system. When I shoot that spot with the pyrometer its 190deg. If I squeeze a rad hose it stops boiling. Thats what tells me its a trapped air bubble.

 

Im going to try a new rad cap, I was thinkin of this. It is about a year old, it came on the dual core radiator I got from the custom rad shop by my work. Ill try an OEM rad cap and t-stat.

 

The Beast I drive- What were the issues you were having prior to drilling the t-stat. What did it change?

What were the issues you were having prior to drilling the t-stat. What did it change?

 

I was having the problem where the T stat would not open when it was supposed to, it would get up to almost to the red on the temp guage before it would open, then it would open and work fine. Knowing how easy it is to blow a headgasket on a boosted car, I didnt want to risk it, and I am too cheap to go 30 miles out of my way to get an OEM t stat, I plan on replacing this motor soon with a 2.5 and am trying to spend as little cash as possible, so there are more than a few semi-permanent "temporary" repairs. I just drilled those 5 holes like I said so coolant could flow at least a little no matter what. Doing that and switching the fan to constant power has made a big improvement, it doesnt overheat in the drive through anymore :banana:

-Bill

I was having the problem where the T stat would not open when it was supposed to, it would get up to almost to the red on the temp guage before it would open, then it would open and work fine. Knowing how easy it is to blow a headgasket on a boosted car, I didnt want to risk it, and I am too cheap to go 30 miles out of my way to get an OEM t stat, I plan on replacing this motor soon with a 2.5 and am trying to spend as little cash as possible, so there are more than a few semi-permanent "temporary" repairs. I just drilled those 5 holes like I said so coolant could flow at least a little no matter what. Doing that and switching the fan to constant power has made a big improvement, it doesnt overheat in the drive through anymore :banana:

-Bill

several yrs ago on a long trip the temp gauge went also for me to the red line before opening up...no matter what I did as to try to remove the air...even with the front up on jacks, the air pocket was there ...later I found out that it was caused by a plugged

heater core..when the core was changed out..all was fine

I thought my heater core was bad too, but after I did this, i have working heat again :confused: that and I fixed my heater fan, it had 2 mummified mice in it making it vibrate like a paint mixer :-\ All is well now though.

-Bill

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