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belvedere 01-29-2008 03:22 PM

HELP! Can't Cure Air Pocket In 02 WRX Cooling System
Hey everyone.

Despite numerous searches including the phrases (air pocket), (coolant bleeding), (coolant refill procedure) etc, I was unable to find anything that could help me with my current problem.

Knowing that Subaru coolant systems aren't the easiest to bleed, I did some research and found that many people have experienced this problem, but I was never able to find a solution. Basically, my radiator cracked (in -9 degree F weather) and I replaced it, but when under stress, the car starts to overheat. It will run idle all day long with no problem but climb a hill or stay on the highway for awhile and the temp starts raising very quickly. After poking and prodding, it seems that the coolant isn't circulating all the way. I say this because the top radiator hose seems warm/hot as usual after warming the engine up, but the bottom radiator hose to the thermostat remains cool, and not warm at all. There are also a lot of bubbles in the upper coolant reservoir (not the extra/overfill reservoir with the fill line)

In addition to replacing the radiator, I replaced the thermostat and all hoses as well.

Also, I did find the "official" Subaru guide ( [url][/url] ) for replacing engine coolant and it mentioned a bleeder cap that should be pulled. Am I to understand this is on the radiator itself (which in my case is gone since I replaced mine), or is it somewhere else?

Extra info:

2002 WRX
60,000 Miles
No performance mods.

I would greatly appreciate any feedback whatsoever as so far, I haven't been able to get any info anywhere else.

Help me wrxtuners, you're my only hope.

b7g 01-29-2008 09:09 PM

i did a wrx with a radiator without a filler cap. The motor was warm, it idled for maybe 30 min. We made sure the over flow tank had enough coolant and the radiator was full, we put in coolant through the top hose (bending it a little so the engine connecting side faces up) untill full. Than filled up the filler tank and started the car for 15 seconds, turned off the car and carefully openned the collant filler tank, and refilled it. The procedure has to be repeated several times untill the coolant in the filler tank no longer goes into the system, that is, there will be some coolant in the tank--the system is full. The down side was starting and stopping the car several times, but i found this to be the only way in our case.
Good luck and hope this helps a little...

LiL Shoaf 01-29-2008 09:10 PM

Fogive me if this double posts.. I already did one reply but it's not posting..

Anyway, I had the same problem when I installed my Koyo Rad. What I had to do was open the cap on that overflow tank (the one located on the intake manifold) and keep squeezing the upper rad hose while refilling the tank as the level drops.. After a ton of squeezing and time my issue was resolved.

MilesFox 01-29-2008 11:07 PM

if you have bubble coming up as the car is running, you may have popped the head gasket, forcing exhaust into the coolant and pudshing the coolant out into the overflow

Jave 01-30-2008 04:15 AM

I didnt have any issues filling my car after my hybrid build. just fill from the top(not rad cap) and keep filling. carw ill be fine, also it helps to know what the system holds to beginw ith.

belvedere 01-30-2008 10:27 AM

Thanks for the responses guys. The weather looks like it's going to get pretty nasty the next couple of nights here in STL, but hopefully I'll have some time to try a few of these things tonight.

So since I've already filled my system, will I need to drain it and start over?

Jave 01-30-2008 01:04 PM

you would be starting with a clean slate if you did that, but it is up to you.

MilesFox 01-30-2008 02:47 PM

no, draining the coolant is not necessary. not unless it was some 15 yr old car with 200,000 miles, i wouldnt worry about it. in fact, this may aggravate your problem

belvedere 01-30-2008 03:03 PM

I hope to hell it isn't a head gasket. I know the bubbles could indicate a gasket leak but they also could point to the air pocket issue too, right? There's definitely no leaks, no exhaust discoloration, change in exhaust smell, running like crap or anything like that.

MilesFox 01-31-2008 02:22 AM

you could expect to have some bubbles to rise when you are adding coolant. but if there are bubbles just floating up when the car is just running withthe cap off, you may have a head problem.

if that is the case, the car could still run fine and not have any problems until the bubble spuke out some coolant, and you will have to add more.

you can get away with this condition if you keep an eye on the temp gauge and add coolant when you need it.

my sedan had this type of head gasket problem. i would run the heat, and whent he heat got cold it was time to add coolant.

if it is not so bad you can try some block sealer, the liquid glass type sealers, if you in fact determine you may have a head gasket problem.

but with the sealer you have to apply it with STRAIGHT CLEAN WATER, let it do its thing, then drain, then add green coolant

LiL Shoaf 01-31-2008 04:51 PM

Depending on the amount of air pockets trapped in the system you could get bubbles for a while until you "Berp" the entire system free of air.. It if bubbles for ever then i'd worry about the head gasket. But since you just did the rad swap I'm confident it's just air pockets. I also wouldn't drain it at this piont. Let the car warm up and keep burping it..

dumdum 01-31-2008 06:54 PM

It's definatly not a head problem.It is air pockets.Happens ALL the time with the WRX's.Just make sure the vehicle is level and not on a hill where the radiator is the highest point.
[url=]Cooling System FAQ: Read if you want coolant information! - Service & Maintenance - NASIOC[/url]

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