Thermosat replaced over heating

[jerros420]

Hey everyone. I am having one **** of a time on a simple thermostat replacement. I have 1996 subaru outback 2.5 with 245,000 on it but runs like a champ still. here is the thing.
Over the summer I had my radiator go bad on me it cracked right down the plastic. So I replaced the radiator and thermostat but I couldnt get the air out atfter like an hour of trying.
So pressed for time I just removed the thermostat and drove for like 2 months without one. That is until the weather got cold. now with no heat I decided to put a new Subaru thermo in and since I have had major issues.
The first day I did it I drove to work and it was cold out and the everything seemed fine temp was about half way but things felt a bit off I had heat but it wasn't hot so I figured there was air in the system still.
So the next day I topped off with bleeder vulvae open waited for bubbles to stop closed bleeder, ran another 5 minutes. but no heat. so I took it for a ride and it over heated in like 3 minutes. opened the bleeder and steam just pours out forever replace it all and let it cool and the top hose sucked shut.
re-bleed the system still no heat and steam comes out of the bleeder.
overflow it to the full line and no leaks can be seen.
please help!

[jerros420]

I for got to mention I used a head gasket sealant because I was worried that I did damage to my heads driving it when the radiator went to get home and I had some white smoke out the tail pipe. I used this product.

K&W Products/32 oz. FiberLock head gasket and block repair (401224-6) | | AutoZone.com

[canubaru]

i don't think any one here would recommend leak stop of any kind for the 96 - 99 outback engines. if you damaged the head gaskets by overheating the engine nothing is going to correct that except new subaru head gaskets.

but what is done is done. when did you add the stop leak, with the new rad or later when you removed the t-stat?

i would drain down the coolant and refill correctly. normally i would save and reuse the coolant but with the stop leak in it might just start over. (if it were summer i would fill with plain water and save the $12 until i knew it was fixed. but this time of year that could be very risky.)

you do not give much detail of how you filled the system, just that you let it idle with the vent plug open until the bubbles stopped.

you need to fill the system with both the vent plug and the rad cap open. you need to fill the system SLOWLY. if the coolant goes in faster than the air can come out you will trap an air bubble.

i use a 3/8 inch clear tube to siphon the coolant out of the jug into the rad. this goes so slowly that i have never had it trp air. as a matter of fact, i do not even run the engine to burp the system. when i have tried that i lose more coolant than i can get back in, so i do not bother.

this method is so slow that you will get bored but it works. first i do the full gallon and then i do another 1/2 gallon. close the vent plug, top off the rad, and call it a day.

i realize this is extreme and few folks will do it, but in your case what do you have to lose. a few bucks for tubing, $15 for a jug of 100% anti-freeze, and a few minutes during half time to start the process. then check it at the first commercial. and start the second jug. byt the next commercial you are done.

worst case is of course bad head gaskets, but until you fill and burp correctly you will not know.

did the cooling system use any coolant for the 2 months there was no t-stat??
is there black gunk in the rad over flow?
do you have bubbles on the overflow bottle when it over heats?
does the coolant smell like exhaust?

the typical failure mode for these engines is exhaust gases into the cooling system.

good luck.

[1 Lucky Texan]

I didn't notice what brand of t'stat you installed? Was it aftermarket?

also, you may need to change the radiator cap and check the small overflow hose for blockage.

[jerros420]

I used the Larger Subaru thermostat. I filled slowly and let the car run and burp slowly still no heat. Is it normal for steam to be pouring from the bleeder valve. that is one issue that I thought was strange

[jerros420]

I put the gasket sealant in because it was thermostat friendly but I hope it did not clog my heater core. It seams like the coolant is not circulating.

[jerros420]

I just took the thermostat out again and everything is fine now. slight heat which I am sure will go away once I drive in the cold..
i DONT GET IT. IT IS A NEW THERMOSTAT AND IT JUST SHOULD BE SO HARD TO GET THE STAT TO OPEN AND AIR TO MOVE OUT.
Any issues that can cause this problem. Such as water pump or head gasket?

[canubaru]

no heat is an air pocket problem, the coolant is not circulating.
this could be caused by bad head gaskets leaking exhaust into the coolant and building up until you have an ''air lock'' or an air pocket.
or it could be caused by improper filling which traps air in the system.

removing the t-stat greatly increases the rate of flow for the coolant. this usually allows the coolant to ''push'' the air pocket around. this eliminates the air lock and tends to eliminate the overheating since the coolant is circulating.

you said ''subaru t-stat'', was it from the dealer?
test it in a pot of water on the stove to make sure it is opening completely.

[jerros420]

the tstat was water tested and worked fine

[LvDirtJunky]

Here's a trick i do , take the radiator cap off , unscrew the bleeder valve ,take it out , slowly fill up the radiator "Threw the bleeder valve hole " , once its too the top , fill up the radiator cap side , although it should be full then start it , it shouldnt have any air in it then . Its the only way i get the air out of mine