After a massive coolant loos the engine should not be operated until the
problem is resolved. With the coolant temperature sensor relying on the
proper flow of coolant you can't completely rely on it if the system can't
hold coolant or it is not flowing. When you refilled the system did you fill
the pressure tank inside the engine compartment, (good), or the refill tank
behind the license plate, (not good)?

In addition if it is the water pump a sudden massive coolant loss there
often means a bearing failure. This usually means the pump impeller is now
eating into the case.

The usual things to look for are the pump, hoses, the water pump return
pipe, especially the heater return tee braking off, and unfortunately the
outer head gasket.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Ian Stewart
Sent: Saturday, March 24, 2012 10:12 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Severe coolant leak

Hello, I have a 1987 2.1L 4-speed, and last night, I experienced a sudden
and severe discharge of coolant from the left side of the vehicle. When I
parked it after a two-mile crosstown jaunt, steam was coming out of the
driver side air intake, and a big puddle of liquid was on the ground. I
managed to get it back home without overheating, and left it until the
morning. This morning, there was no coolant on the ground underneath the
vehicle, but a much smaller (about 1/2 inch diameter) drip began to occur
once I refilled the coolant bottle. I looked inside the engine compartment,
and my current hypothesis is that it's one of the gaskets or hoses on the
water pump. That seems to me to be the only component on that side of the
engine capable of generating such a gusher. Also, nothing directly beneath
the coolant refill bottle, recovery bottle, or any of their hoses is wet.
However, I'm still getting a significant amount of coolant dispersed all
over the back of the van in droplets when I drive it. The overheat light
doesn't trip; but the temperature gauge is registering slightly higher when
the engine is warmed up, 3/4 of the way up instead of the usual 2/3. Water
pump was replaced almost 4 years ago when I had one of the heads replaced.
In any event, I am going to be putting the van up on a mechanic's rack
Monday morning and trying to pinpoint the problem. I would appreciate
suggestions for things to look for, and things I should probably go ahead
and replace. Potentially water pump, hoses and clamps, thermostat,
temperature sensor...?