22-03-2020, 06:02 PM
The vacuum wiper motor on my 1927 Chummy had never been connected to the inlet manifold since I bought it so I recently dismantled and serviced the motor (including soldering some small cracks) and it seems to move freely when I operate it by hand. However, when I attach it to the outlet on the inlet manifold it barely moves at all even though some vacuum can be felt at the motor if the regulator screw is removed.
Can anyone suggest why the vacuum might perhaps be too weak. I am using 4 meters of 4mm clear plastic tubing which I am reluctant to cut down to the required length (2 metres?) until I have sorted out the problem. 4mm is the correct internal diameter for attaching it snugly to the motor and to the spigot on the manifold. Physics was not my strong subject at school but I would have thought that the length of the tubing (within reason) should not significantly affect the delivery of the vacuum from the manifold to the wiper motor.
Compression is good on all cylinders and therefore I assume that the pistons are drawing in air efficiently.
Any thoughts/suggestions would be gratefully received
Can anyone suggest why the vacuum might perhaps be too weak. I am using 4 meters of 4mm clear plastic tubing which I am reluctant to cut down to the required length (2 metres?) until I have sorted out the problem. 4mm is the correct internal diameter for attaching it snugly to the motor and to the spigot on the manifold. Physics was not my strong subject at school but I would have thought that the length of the tubing (within reason) should not significantly affect the delivery of the vacuum from the manifold to the wiper motor.
Compression is good on all cylinders and therefore I assume that the pistons are drawing in air efficiently.
Any thoughts/suggestions would be gratefully received