>The "low coolant level" blinking light comes on and goes off in my
>'87 Vanagon..  It seems to be in sync with the potholes on the road :-)
>Of course, I deleted all the e-mail that went on about coolants, maybe there
>was something about the coolant level sensor...  I'd like to check to
>see if it is a badly connected wire or something.

>Could anybody enlighten me as to the whereabouts of the sensor, and the
>whereabouts of the (undoubtedly) many connectors the signal has to
>travel through until it gets to the dashboard?

>The cooling system is also losing some coolant, at about the rate
>of .75 Quarts every 1,000 miles.  Would this have anything to do
>with the coolant level light?  I am keeping the coolant level 
>correct at the overflow tank, by adding coolant every week, and I
>have not noticed any change in the operating position of the engine
>temp indicator.

The coolant sensor is mounted on top of the coolant expansion tank.
That's the bottle directly to the left of the one in which you add 
coolant.  It basically consists of two electrodes that stick down 
into the coolant which acts as a resistor to complete the circuit.
When the coolant level drops, the circuit is opened.

This could happen if you are letting the coolant get too low in the
refill tank and/or have a leak.  The refill and expansion tank may 
look full when the engine is off, but the next time the light comes
on, check the tanks then without shutting the engine off.  Also, 
accelerate the engine a bit while you watch the coolant level and see
if it stays constant.  Sometimes with a leak or air in the system, 
coolant can be sucked into the system when running and drain back 
into the bottles when you shut down.

The fact the light comes on when you hit pot holes could be an
electrical problem.  But if you know already that you are losing
coolant, I'd be inclined to think it was due to coolant in the
expansion tank being low and sloshing when you hit bumps. 

Where do you think that .75 qt per 1000 miles is going?  Look 
around for leaks.  Have you seen any coolant spots where you park?
In addition to hoses, check the underside of the engine for signs
of coolant, especially coming from above the gravel guard protecting
the push rod tubes.  Also look from below up past the oil filter. You 
can see the bottom of the water pump from there.  If the leak is
in that area it may also leave a mess on the top side of the oil
filter.

John Clavin      jjc@bga.com
Austin, TX