cooling system air bubbles

[treed2@u.washington.edu (T. Reed)]

I guess I should have mentioned that when the upper radiator hose is
bulging like that, it's full of air, not water. I've felt it before under
normal warmed-up operation and if I squeeze it I can feel the water
running inside. That is not the case in my current situation, at least not
until the engine gets VERY hot and the fan finally turns on.

Furthermore, it's not an odd-shaped "bad hose" bulge, but rather just a
general "bloat", like a balloon half-filled with air. I hear you on the
cooling system pressure thing - had troubles there when my coolant level
sensor cracked about 2 yrs ago. That was a bit of a pain to track down
because the leak was so small.  And as far as bad hoses, my T-shaped 3-way
oil cooler<->water pump<->block hose blew right after I put my 2.0 in.
That was a nasty $55 surprise that got tacked on to my already expensive
engine project..

Anyway, I made -some- progress today on purging the air. I let the engine
warm up and the fan turn on by itself (at almost 7/8 of full on the temp
gauge), then the engine cooled down to 3/5ths or so and I opened the
coolant tank and held the throttle at 3500-ish. The coolant level in the
bottle went shooting down and the tank went completely dry. I added as
much water as I could before the level came back up (which it did rather
quickly) then I couldn't get the level to go down again but it's still
progress. I'll work on it some more later.

Now the fan comes on at around 3/5ths on the gauge rather than 7/8ths. It
should come on (in my past experience) at or around halfway on the gauge.
So it's getting closer..

Anyway, thanks everyone for your suggestions..

-Toby

On Sun, 23 Mar 2003 SailingFC@aol.com wrote:

> When was the last time you changed that upper radiator hose?  Sounds like you
> need to replace the hose.  If it's bulging out, it's a weak hose and the
> cooling system is not able to maintain pressure.  If there is no pressure in
> the cooling system the system can overheat.  I bet the hose goes back to its
> normal size after you open the reservoir.  Remove the hose and inspect it,
> it's probably split or separated inside.
> GL.
>
> -Dick-
> 78 Scirocco
> Original Owner
> http://members.aol.com/sailingfc/
>
>
> In a message dated 3/21/03 3:50:57 PM Pacific Standard Time,
> treed2@u.washington.edu writes:
>
> Okay, since we're on the topic of cooling systems I'll bring this up..
>
> Basically, I'm suspect that I still have air in my cooling system. The car
> runs at normal temp (a hair above the LED) until I get to a stop light.
> After 45 seconds or so of sitting, the temp has risen to 3/4 on the gauge.
> That never happened before, so I'm guessing there's still an air pocket.
>
> I already burped several huge bubbles out including one that was over a
> liter (it took that much water to fill the reservoir back up)
>
> I haven't had a chance to idle the car and watch it warm up to see if/when
> the fan is coming on (although it is on when I'm sitting at a stoplight
> like that, since I had the blower on defrost and that spins up my rad fan)
> because its so freaking rainy, but the radiator fan switch is only 2 years
> old anyway and I don't think that's it.
>
> When I have driven for a long time and park and pop the hood, the upper
> radiator hose is all bloated like its full of air but if I open the
> coolant reservoir partway its pressurized and just dumps coolant
> everywhere.
>
> Any foolproof methods you guys use to blow -all- the air out of the
> cooling system?
>
> I drilled a 3/32" hole in my thermostat in that part that looked like it
> opened (the large disc shaped piece, not the spring-loaded small one at
> the other end).. I revved the engine a bunch with the reservoir cap off, I
> did a few heating/cooling cycles. I drove the car probably 60 miles
> since I draining and filled the coolant.. What else is there?
>
> I hate vw cooling systems..
>