Sounds as though your thermostat may be sticky and maybe the wrong value.

Replace it with a new 87 C thermostat and seeif that cures your woes.

The Vanagon cooling system generally bleeds best with the front end a couple
of feet in the air. It gets the air out of the front heater better.

Good Luck, Jake

On 12/17/06, Don Hanson <dhanson@gorge.net> wrote:
>
> Ok, I haven't been around the list here for long enough to know if I am
> gonna get a bunch of "Told-ja-so's" and "What did you expect?" and "serves
> you right for thinking you know more than Fritz and Franz at VW" but I am
> going to ask away.  If there is better place to get some ideas, point me
> there if you will, or if this is something that also happens to WBX vans,
> then perhaps someone would be so kind as to clue me in.  I am sort of new
> to  the W/C vans..
>
>   So a while back I was having overheating issues and did a bunch of work
> on the cooling system..New water pump, thermostat, coolant temp sensor,
> Flushed the radiator and replaced a couple of hoses. New belt, plus added
> Dextron coolant as per specs.  Still  having overheating till a Vanagon
> savvy friend pointed me to the radiator bleed screw.  That pretty much
> solved all, for a while..But today, my front heater started blowing
> cold..."Uh oh" says I, "My coolant is low or my belt is loose"..The temp
> gauge climbs up to about 1/2 way to hot with the defroster blowing ice cold
> air and then..the heater gets hot again and the temp gauge goes right down
> to where it runs, which is just into the warmed up range... then again, cold
> air and gauge climbing..for about 4 miles, then again warm air and back
> down  with the temp...No symmetry to the episodes..other than for about a
> week everything was just fine until today.
>     So, I get back to my shop and find the coolant slightly low...it took
> about 2 quarts..Then, I jack up the rear and open the bleed screw on the
> rad...put another couple of quarts into the rear coolant res. till it burps
> the radiator out and I get coolant overflow there at the bleed screw.
>      OK, some more data points..The motor is a 92 Cabriolet motor (1.8liter 8 valve) and I've driven it cross country without any heating
> problems. No problems till just  recently.  The front heater/defroster has
> never blown hot at idle that I can recall, but once off idle, it works just
> fine.  The rear heater..I noticed a slight coolant odor when I first turned
> it on, so I checked that also and found it a little weepy at one
> hose..tightened that and opened the bleed screw, which is
> 'semi-stripped'..There was coolant right there, no air at the hole where the
> bleed screw came out..I will probably put some silicone in the threads to
> seal that for sure...The rear heater blows hot whenever it is on...when, of
> course, the coolant is up to temp..  Maybe I need to change the waterpump
> pully to get more coolant circulation?
>   So, is there some kinda valve or temp. sensor that controls flow up to
> the front..the radiator and the heater?  I seem to have intermittent coolant
> circulation up there..Remember, new water pump, flushed radiator, and fresh
> anti-freeze.  Belt is new and properly tensioned...
>   Should I be thinking the radiator needs to be replaced?  Anyone tried
> one from the Bus Depot..they have a killer price on rads...
>
>   Thanks in advance..and I don't mind being "told ya so" about having a
> changed non-standard Vanagon..
>   Don Hanson
>

--
Jake
1984 Vanagon GL
1986 Westy Weekender "Dixie"
www.crescentbeachguitar.com