Karl as far as I know there is only one bleeder valve and it is located
on the top
left of the radiator. The valve over the engine is a by pass valve. It
purpose is to send water to the radiator by passing the thermostat in
order to get air out and should be be unscrewed counter clockwise until
all air is out. Be careful this plastic valve is very fragile.

Karl F. Bloss wrote:

> Our '87 has been heating up to the point of the fan kicking in much
> too early lately and I suspect an air bubble in the cooling system.
> I did change the temp sensor II, so it's not unlikely.  So, I wanna
> bleed it.
>
> I looked in Haynes manual and they mention and show a bleed valve in
> the engine compartment right on top of the thermostat housing.  If
> I'm not starting with an empty cooling system, do I need to bother
> with this; i.e. isn't the radiator bleed valve enough?  All other
> bleeding instructions I've seen only mention the radiator bleed
> valve.
>
> Thanks in advance.
>
> -Karl
>
> Karl and Kristina Bloss, Trexlertown, PA
> '87 GL Weekender  "Beverley"
> VW shop list: http://www.enter.net/~bloss/vw/vwshops