Cooling woes... Air???? ** EDIT 3/2

[Navig8r]

OK... this problem did not exist until yesterday, when I changed the thermostat.(Car would run cold anytime it was not under load...such as long downhills on highway)
So, new thermostat is in (old one had mega-sized bypass hole), filled system, ran it for a while.. seemed OK.
Went out last night... ran OK for 30 minutes or so, including 15 minutes of highway driving.
A few minutes after getting off the highway, it began to run hot, with no warm air from the heater... I'm thinking air bubble.
Pulled over and let it cool for a few minutes, then took it easy for a few minutes to my friend's house.
I let it sit for a few hours. Then we opened the cap, topped it off, and started it up. Continued to top it off after t'stat opened.
Drove home OK, except less than a mile from home, temp crept up to hot again.... AAAARRRRRGGGGGHHHHHHHHH!!!!!!
This AM... parked it facing uphill, opened bleeder and cap, and topped everything off. Ran it till it warmed up... topped off... capped up and went for a ride.
A few miles down the road... under load... runs hot... not WOW hot, just hot... with no heat from the heater.
Limp home, open bleeder.... steam everywhere.....
let it cool.... top off... go for a ride.... back to running hot after a mile or so..... not as hot as before, but hot... There is heat at the Heater this time.
Currently it is parked facing uphill... hoping this is just air......

Any thoughts??? Air???? How do I get rid of it????
I've dealt with this before on other vehicles, but no other air pocket has been this stubborn.
I know it could be a HG... but it would seem odd to coincide with me opening the system yesterday.

Thanks for reading all this!!!!

** UPDATE **
2 weeks ago, I replaced aftermarket t'stat with SUBARU t'stat. Also, new upper and lower hoses, and new cap. Re-filled, ran to operating temp with cap off.... good flow, topped off, let cool, topped off... repeat 4 times!!!
Go for drive.... 5 minutes, overheat, air bubble.... no heat....
Let cool, top off, drive home... have heat, then... no heat, but not overheating yet.
Currently parked, facing WAY uphill.... gonna run/bleed a few times today before driving again.

Anyone else had this much problem with air?????

BTW.. checked for HG by using chemical 'sniffer' that samples air in radiator for CO2..... OK both at normal temp and when overheating.

[shazapple]

Thats pretty much the only way. You can try squeezing the radiator hoses.

[Navig8r]

toppped it off... warmed it up, t'stat opened, topped it off, capped it, let it cool.
Topped off, warmed up, topped off... went for a ride... AIR again!!!!
BIG bubble had worked to rad... blocked flow....
got it to work out... topped off..... went for a ride... a few small bubbles showed themselves via the temp guage... then another blockage....AAARRRGGGHHHHH!!!!!! :evil:
I guess I'll continue to repeat until it's all out.... seems to get a bit better each time..

I DID figure out my biggest mistake, though.
I filled the block via the top hose. I should have slowly added only through the radiator. Filling the top hose allows air to get trapped 'behind' that coolant in the block. Filling via the radiator (slowly) would allow the block to be filled from the bottom up, via the lower hose, through the thermo bypass, pushing most air ahead, up and out.
Similar to how you add gear oil to an outdrive or outboard lower unit in a boat. Minimizes trapped air......
Hmmmm.. now where was my brain when I was filling things the first time?? :roll:

[shazapple]

Yeah, it took me a couple days of topping up before my system was completely full. Although I filled it through the rad cap, so after a drive or two the car stopped overheating.

[HeresMyMind]

mine did same thing, guess where is is? the shop.. getting a new HG water pump and timing belt. woot. subaru Hg's

-B

[Plays_with_Toys]

Make sure your new thermostat either has the little dingle check valve or a hole drilled in it. Cheaper t-stats don't have this.

Next, get the car to operating temperature and open the bleeder screw on the left side of the radiator (as your facing the car). It's at the very top, little plastic deal. As soon as coolant start flowing out of that hole put the screw back in. This should help release air in the system. When I filled my radiator, I opened this screw, then poured down where the radiator cap goes. You can also try burping the system by squeezing the top hose.

[Navig8r]

I actually noticed this t'stat has a very very small bypass hole...... the old one had a large hole..... I guess that would help with re-filling.... allowing coolant to get in through the lower hose, and push air up, and out the top hose, and bleeder....... Could be why mine is taking so much effort to bleed.
The old t'stat had the car running cold on downhill runs, and it took forever to warm up, so I guess this is trade-off.

BTW, yes, I am still working air out..... I dont need the car daily, so I've been 'burping' every evening after work...PITA!

[decke48]

to get the air out you need to leave the radator cap off and let it warm up until it starts to perkulate or boil and keep topping the radiator. or some subaru have valve on the top left of the radiator if your looking at it sits rights near the top radiator hose. you can open that too if you would like to. just dont drive with it open. an easy way to warm up your car is to hold the throttle at 3,000 rpm, beats letting it sit to warm up. but always check the level at idle.

[Navig8r]

OK, so I think I solved the problem. Yesterday I drained the whole system, and installed a new SUBARU thermostat. Also did new top/bottom hoses while at it. Upon closer inspection, the t'stat I took out had NO bypass hole. I am pretty sure this was contributing to my problems somehow.
Normally I am not a big fan of dealer parts. Typically siilar or better quality can be had from aftermarket sources for less $$.
The thermostat, however, seems like a good investment, at less than $20.00 from the dealer, with the gasket.

Funny (to me) sidebar:
I know a lot of Subaru parts are interchangable, but the t'stat is incredibly so. I went in and said "I need a thermostat"..... guy behind the counter says "OK" (and I am expecting usual questions, year, model, etc)
He puts one on the counter..... No questions asked... I ask "Are they all the same?" he says "Yup"..... I ask "Even the older ones?" He says "What do you have?"...... me: "'98 Legacy" Him: "Yup"

[shazapple]

Yeah, I always check the dealer since you would be surprised what is expensive and what isn't. The subaru dealer here had remanufactured Subaru alternators for $120, which was cheaper than fixing mine or going aftermarket.

[Navig8r]

Yeah, I always check the dealer since you would be surprised what is expensive and what isn't. The subaru dealer here had remanufactured Subaru alternators for $120, which was cheaper than fixing mine or going aftermarket.

Thanks for puttin the whammy on my car! I somehow killed the alternator during all this cooling work..... only $79.00 at the dealer for a reman. (with core return, of course)

Now.... to get the rest of the air out of this damn cooling system! :evil:

[Navig8r]

bump/edit

Anyone had this much trouble with air????

[Huffer]

Not me.

[Plays_with_Toys]

I don't know the exact procedure for getting air out. For me it was doing this and that and crossing my fingers.

What I did was I unscrewed the plastic screw on the left side of the radiator then filled the radiator so the air had somewhere to go. When I was getting close to max level of fluid, I closed off the screw and would squeeze the top radiator hose with quick spurts. You'll see the water level rise in the filler neck, and bubbles shoot out too. I just kept doing this until no more bubbles were coming out when I squeezed. Capped off and then warmed up the car. After warming up I filled the overflow bottle with fluid (it'll try to syphon fluid from here when the system cools, if there is no fluid, it'll draw air). I also then burped the hose again. The other check is you can bring it up to operating temperature (with the cap closed so you can actually pressurize the system), then open the plastic bleed screw at the top of the radiator. Air will escape and then fluid will start coming out. When the fluid comes out, screw it back in.

[Navig8r]

Found the problem..... Head gasket, or possibly cracked head :evil:

Hard to tell EXACT spot where the leak is coming from, due to obstructions, but I'm hoping gasket only.
Oh well....... I guess I know what I'll be doing with my free time in the forseeable future.

[Plays_with_Toys]

Well where is it generally located? I thought the same thing two weeks ago and it turned out it was the waterpump leaking at the gasket. No puddle because it was burning off on the exhaust manifold.

[Navig8r]

Bubbling / leaking from corner near front of engine, passenger side. Hard to see exactly, as it is under the upper hose.