Having correctly connected and checked the vacuum pipes on my sons '93 Cooper SPI, at his request I have fitted a TIM vacuum gauge (teed into the vacuum pipe between inlet manifold and air filter).
Although the car now starts and runs fairly well, we were surprised to see the gauge reading somewhat low - hovering at the low end of fair (around 7 ins/hg) and dropping to 0 when dipping the throttle. I found that by removing the vacuum pipe from the air filter and blocking it with my finger the vacuum gauge would read more correctly - idling at around 18/19 ins/hg. This led me to investigate the air intake duct and flap valve. The flap valve is very stiff and does not drop correctly to closed when cold, nor open fully upon starting therefore operating incorrectly and always allowing some hot air int the air cleaner.
For the time being I have blocked of the pipe leading from the air filter to the inlet manifold.
Can anyone advise
a) How severely blocking this pipe off will affect cold weather driving etc?
b) Is there any way of getting into the vacuum diaphragm unit and flap valve to try and repair it?
c) I also suspect that the Thermac valve/switch is faulty - is there an easy way to test its operation?
Any advice welcome!!
