I was performing my annual tune up / oil change on my 89 Westy today. I
started off by checking the oil level but I notice the coolant
filler/reservoir tank is totally empty. What happened? I filled it a
couple of months back when it was just below the Min mark and now it is
bone dry. My immediate thought of the dreaded inevitable water boxer
head leak which I have been lucky so far.

I crawled under the engine to see if there is signs of the leak. Sure
enough the left rear header pipe is wet and it is unmistakably coolant.
Very carefully I visual inspected the head on the driver side and there
is no sign of coolant residue. Suspecting the water pump I check that
too and there is also no sign of coolant.

Time to look from above so I open the rear engine hatch. I can see much
trace of coolant clinging to the outside of coolant expansion tank,
especially what looks to be the seam of the top and bottom halves. The
plastic expansion tank must developed a leak at the welded seam, I
thought.

I more carefully inspected the tank with better lighting and I notice
the pool of coolant in the dimple at the top of the tank where the
coolant level sensor resides. Without the necessary part to repair it I
didn't want to disrupt the area. I just wanted to see if the leak is
from within the sensor, or leaking between the sensor and the tank. I
unplugged the sensor connector and it is bone dry on the contacts so it
appear the lead is between the sensor and the tank. According to the
Bentley there is a o-ring. The o-ring must became harden over all this
years and now does not seal under pressure. Since it is weekend I
decided not to unscrew the sensor in case I need to use the vehicle
during the weekend.

I was relief that it is not the dreaded head gasket leak.

I proceed to a complete tune up including changing the spark plugs,
distributor rotor, distributor cap, air filter, oil filter and change
the oil with Mobil 1 5W30 synthetic.

I also thoroughly wiped down the ignition wire with soap and water as
well as every parts I can clean in the engine bay. If there is a
cleanest Vanagon engine bay award I think I stand a good chance of
winning it.

- Vince

http://gipsyflies.home.comcast.net
1989 Vanagon GL Camper
1993 Mazda Miata
1996 Land Rover Discovery
2005 Mini Cooper S