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boiling overflow coolant


Cmosfet
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Hi all,

Sorry for longish post....

Still trying to get my loyale reliable. Its a 1991 4wd spfi, 220k on at least the chassis. I have replaced ALL coolant hoses, thermostat is a new napa one. I know i need oem. It will be ordered today. I have removed the radiator and flushed with hose. I was reasearching this site last night like mad and read that does not mean very much? I also flushed the heater core back and forth a few times...also read that will not hinder cooling even if it was clogged abit. I drove about 20 miles yesterday and coolant got a little above the c. Drove more and it reached middle and maybe a little above. Was pretty happy i got the cooling system figured out. Drove around more listening to the front wheel bearing i need to replace and when i got home i heard gurgling. Shut off car and the overflow was boiling so bad it was shaking. Temp still in the middle. Earlier this week, I have also seen a drop of coolant on one exhaust header bolt driver side. Replaced both header gaskets and i dont see it. I searched on this and could be a crack somewhere. Both studs on that side came out but looked ok.

I am reading like mad but am kinda stuck on what to do next. I am pulling timing covers off today to check for water pump leaks and what not. (Also seen a small bright green blob on timing covers bottom near pump) Similar posts i get that the radiator is bad..is this the right track.

 

Again, sorry for long post...any help would be awesome.

In case it helps .. also replaced: plugs ngk,wires ngk, cap and rotor, intake gaskets oem,pcv oem,tbi gasket oem all vacume hoses. And rad cap oem.

 

Also, is there anyone in the spokane wa area that would be willing to meet up and give me some reference as to where i am on how this thing is running, i know no one with an ea82. My sti is no reference :)

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Here's what you do:

 

Start with the engine off and car cold (not run recently).

Remove radiator cap.

Fill coolant to the level about halfway up the fill pipe, so you can clearly see the surface of the coolant. DO NOT put the radiator cap back on.

Start engine. Apply E-brake and leave in neutral. If you have a helper, have them sit in the car and rev the engine to 2000RPM or so. If no help is available, it will just take a bit longer at idle speed.

WATCH the surface of the coolant, for a few minutes.

You might see a few bubbles, medium to largish at first, gurgle to the surface. This is normal.

IF you see a constant stream of tiny bubbles, stop the car. You have a blown head gasket.

If you don't see a steady stream of tiny bubbles, and the coolant level rises to the top lip of the coolant add pipe, turn off the car. No head gasket leak.

 

What happens is called a "compression leak" - the pressure from the cylinder blows through a gap in the head gasket into the coolant passages around the cylinder. This raises the pressure of the coolant system, and eventually overcomes the seal of the radiator cap, blowing the coolant into the overflow reservoir. The only fix for this is to replace the head gaskets.

 

Hope this helps!

Edited by BirdMobile
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Ahh ok, thank you!! will do that today. I was planning on pulling motor and re seal but not this soon. Ya the previouse owner did say it overheated a few times on him and he admitted to not being very nice to it, as far as maintenance. But its rust free and in good condition so it would be worth it. Thanks again...will post back on resulys.

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Ok, i did the test and i did not see a stream of bubbles. Coolant did rise to the top and spill abit. As i reved it would suck back in and then rise again. Top hose was hot so i guess the tstat opened. I put car on ramps and got it warmed up. Shut it off, let cool and topped off while squeezing hoses and kept topping off. Did this a few times. I still hear a little gurgling behind dash so i guess i will keep trying and make sure all air is out. Although the gauge did not get to half like before. Maybe i need to drive around more? Thanks again for the help, ill keep trying and reading. And order an oem tstat :) i am also thinking of having the radiator looked at or cleaned out or replace it... i dont know how old it is...

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It sounds to me like your not having over heating issues at all then? you said that the temp gage doesnt get much higher than the middle? The gurgling sounds like air in your heater core. maybe try lifting the front up or parking on a hill while you run it, and fill to the top?

 

Is the fluid level consistently going down? if you run it and lay under the engine bay is there any drops? Are you getting white smoke? if the answer is no to these i dont think anything is wrong.

 

maybe look into getting a new radiator cap? if your leaking from the overflow reservoir while you drive or while the motor is at temp, that might be a source of your leaking. 

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Based on what I read, this is all good news.  I would suggest as well a new rad cap.  If the rad isn't pressurizing the coolant will boil at normal operating temp. (Pressure keeps coolant from boiling).  If you have a rad cap tester available can always try that instead of buying a new one.  Most auto shops will also test it for free.

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Thanks for help! Ya i dont see any smoke at all. I have seen a drop of coolant on bottom of timing cover near pump. I just pulled off the end covers to see more. Will probably get rid of all the covers soon. Fresh new oem rad cap. Oem thermostat will be here today. I have been puttng car on ramps to purge. I will do again tonight with new tstat. Im not sure of the radiator condition, i did have it out and ran water through it but like i said im not sure if that is a good test? Earlier when i was purging and left the cap off, it did geyser out if the cap hole... i dont think i let it run that long this last tine...uh..thats not normal is it?? Geyser out the rad cap opening...Thanks again, great place!!

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As the car temp rising so does the pressure in the cooling system with the cap ON. If you let the car rise to normal operating temp and try to take the cap off. it will blast out the top. Dont do that. Let the car sit and cool down while it is OFF, give it a good 10 mins or more. Then take the cap off and turn the car on, let it run to normal running temp and let the Tstat open. Make sure once the Tstat is open you are getting flow, this should be evident when the drivers side radiator hose begins to heat up. And you should begin to see swirling in the radiator with the cap still off. ( make sure your fluid level is the same level or just a tad below the radiator cap filler extension.) That will tell you your pump is working. If you have head gasket issues, like Bird said you will see a steady stream of bubbles coming up. ( small bubbles ) After awhile the fluid will heat up and expand and start flowing out, so at this point either put the cap back on or turn it off so you wont waste fluid. The best home test ive seen is running it on the road, and feeling the fins for dead spots. Or getting a line off your water heater in your home, and running hot water through it. feeling for cold spots, aka blocked passageways.

Edited by wagondragon
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Ok well i received the wrong tstat so i will have to send it back. When i went to replace it i noticed again coolant drips on the header stud. Driver side stud closest to firewall. I dont see it collecting from anywhere else and the bolt is nice and clean and wet. I think i will pick up a compression tester and check. From the searching i have done looks like a crack in the head? I see no smoke at all..well except what is dripping on the manifold haa... Im going to go ahead and do the tests again, burp coolant and do another bubble test. Oh, both studs on that side came out if thats any clue. They came out and went in ok though.

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Ok well i received the wrong tstat so i will have to send it back. When i went to replace it i noticed again coolant drips on the header stud. Driver side stud closest to firewall. I dont see it collecting from anywhere else and the bolt is nice and clean and wet.

 

Check heater hose connections.

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I having a problem with the new oem thermostat. Does the oem one have a rubber ring around the flange? The dealer said this is the cross for my vin but it dont fit at all. Also said the 21200AA121 is not available. I got a 212100aa120 which is supposed to work but i dont see how...

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