Parking brake start is a common problem in 77-80 MGB's. It is a bad
diode in the brake warning circuit. There are 2 of these diodes in the
late model cars, not always shown in the wiring diagrams. They are found
by removing the glove box & following the wires until you find a small
rectangle 1/2" x 3/4" with wires in & out. The diode is usually brown,
black, or red in color. It has a male terminal on one end, female on
the other so you can only plug it in in one direction. I could never
find a source for them, so I relied on pulling them from salvaged
harnesses or cars.
The MGB heater control valve is a monument to poor design & poorer
construction. I saw a good friend lose a race due to a leak that dripped
into the dizzy on uphill right handers. make a base from 3-8" aluminum,
drill & thread a hole in the middle & add a threaded heater hose nipple,
available from NAPA or others. Your friendly auto parts store, NAPA or
equal, will have an illustrated catalog of heater control valves,
including several in-line style units that are cable controlled. Pick
your favorite, paying attention to the hose size. Most heaters use 5/8"
hose, our MG's use 1/2". Shorten the original heater control cable as
required. You should get better flow, easier shut off & on. Also pay
attention to the shut off direction the cable arm moves to shut off so
it will match the dial on the dash
Jim Stuart
1974-1/2 MGBGTV8
1978 MG transforming itself into a 1967 V8
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