When the mornings got cool last fall I turned the heater control on my '68
MGB but I only got cold air from the heater. The control wire moved the
water valve as expected, but with no effect on the heat. I assumed that
the valve was stuck or that the heater core was clogged up somehow. I
decided to postpone the repair until a nice day in the spring. I bundled
up when driving until it was time to put the car in storage for the
winter.
The nice day in the spring eventually arrived. I flushed the heater core:
it was fine and had no sediment. The coolant that I drained from the
radiator looked fine.
When I removed the heater valve it was abundantly clear why I got no heat.
The throat of the valve was absolutely packed with pasty white, gray and
yellow-green crud. The same crud was in the water passage hole in the
block, but it was only about 1/4" deep and easily removed.
The crud in the valve extended maybe 1/2" deep. I easily removed it
by picking at it with a screwdriver.
I put in a replacement valve from Moss and I was rewarded with plenty of
heat. The old valve was in service perhaps 10 years. I installed it
around 1995 just as a preventive-maintenance measure since the original
valve had been in service since 1968.
A graphic nasty shot of the valve with crud can be seen at:
http://www.cse.ogi.edu/~johnhunt/heater_valve.jpg
Has anyone seen this sort of crud develop? I am using normal Valvolene
coolant at 50% concentration. I store the car from November-April and use
the heater only in the spring and fall.
Maybe it is corrosion that develops near the cast iron block - aluminum
heater valve vicinity and collects there due to the restricted area and
only occasional use of the heater?
Any suggestions for brands of coolant that might help avoid future
corrosion?
John Hunt
Portland, OR
'68 MGB
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