Date:         Tue, 23 Jul 1996 09:02:16 -0700
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         natasha!kombi@adobe.mv.us.adobe.com
Subject:      Re: Bubble in cooling system? '87 Vanagon

> So I fill the empty resrvoir (the main one you fill behind the license plate
> ) with water to start with (thinking I'll add coolant next batch as the
> water circulates). I start the engine, and let it run for a while, thinking
> the thermostat will open up the  valeve and coolant will start to flow. But
> after a few minutes of running, I see the heat start to creep up slowly, but
> steadily towards the top of the indicator, and I shut things down for fear
> of a seziure (probably paranoia, but I ain't taking chances!!).
> 
Wait -- that's the wrong coolant tank to fill!  You want to fill the other
tank -- the one with many hoses, blue cap, etc.  The level sensor is in
the top of that tank (inside is a "well" to get this thing to blink when
there is gas present).  If the LED continues to blink more than 5 seconds
after you turn on the key (you don't need to start it) then check this tank
and sensor.  *I* think VW did a good job on this cooling system, although
overcoming the long distance to the radiator is hard (of course indy cars
do this also).  Normally, you just keep the little *overflow* tank (the one
behind the license plate door) filled -- don't let it get empty, or you'll
get air in the system.  The ring-around-the-engine-lid seems to help to get
bubbles out of the system, too.  Normal maintainence is really simple -- 
changing the coolant is not so simple, but doable.  You should plan on
coolant changes once a year.

The level sensor is two wires dipped in the tank.  If you run too much
antifreeze, it doesn't conduct electricity, and blinks the LED.  I
suspect that ALL water would make the sensor (but not your engine) very
happy.  Use the *minimum* amount of antifreeze the manual recommends.
Anitfreeze does not conduct heat very well, and only raises the boiling
point of the water mix slightly.  If you live in very cold places, you
might consider running a different mix summer and winter, but this means
the pain of antifreeze changes twice a year.

> Like any pro mechanic, I THEN break out the shop manual and read about
> refilling the coolant (well after the fact!!). It describes the steps of
> elevating the front of the vehicle, clamping hoses, opening up bleed nuts
> etc. Now I don't have my tools back East yet, so I don't have anything to
> elevate the van with (other than the jack), but I do follow the procedures
> with the bleed nuts. Coolant starts to run out of the radiator valve bleed
> nut (a bit bubbly but seems to subside), but no water which I added to the
> reservoir moves at all... and the temp still continues to rise rapidly.
> 
These engines warm up quickly.  Do you mean it overheats immediately?
The overflow tank water basically only moves when the engine cools down
and sucks water in from this tank.  Also check the valve in the blue cap.
Blowing into the little pipe where the hose to the overflow tank goes
should make a nice duck call.  Sucking should block (not a one-way valve,
but the sucking has to be at 15lbs/sq" or so to release the valve).  A VW
dealer can check this for you with the right tester.  If you need a new one,
you should get the whole tank, which include the cap, the cap alone costs
almost as much and these tanks need periodic replacement -- they crack.  A
tiny (invisible) crack in this tank caused me grief!

> Soooooo..... I figure one of the following has occured:
> 
> 1) A nasty bubble has gotten into the cooling system and is preventing
> coolant from circulating properly (although I had the coolant running out of
> the radiator bleed nut which would indicate some circulation is taking place
> ).
> 
> 2) A blockage has occured somehow in the cooling system
> 
> 3) Water pump has failed (but again, there seems to be some flow if its
> flowing out of the bleed valve, and also there's no tell tale sounds or
> coolant leak to indicate the pump has gone).
> 
> 4) When the coolant sprayed around its shorted the temp sensor/coolant senor
> giving me a false overheat indication (highly unlikely but..)
> 
> There's no coolant leak since I replaced the hose.
> 
> > 
> > if you are talking about the "little hose" that i think you are (the one
> that
> > goes between the power steering pump belt, into the right side cylinder
> head)
> > that's an air-bleed hose. notice that it goes up to a "loop" around the
> engine
> > and that loop is connected to the coolant reservoir.
> > 
> 
> Hmm. don't know if we're talking about the same hose... The one I replaced
> is about 2" long, and probably about 1 1/2" - 2" in diameter (its on the
> right hand side of the engine, wedged between the power steering belts and
> the alternator belts.. in fact optimally you have to disconnect both belts
> to work on this small section of hose). Its not one of those 1/4" diameter
> hoses which connects up at the engine compartment bleed valve..
> 
> Anyway, I'd sure appreciate any tips about what may be going on (and sorry
> for the lengthy description but I thought it might shed some light).
> 
> Damn VW sure made filling coolant a bitch.. do you have to go throuigh all
> this bleed valve stuff when your topping off coolant on an average day (in
> other words when you haven't blown a hose or something)?
>  
> 
> -------- REPLY, End of original message --------
> 
> 
> 
>