68 wiper door

[Dan L.]

When I start up my 68 after it has been sitting (no vacuum in system), the wiper door moves slightly about 1/4 inch up/down. I know this can be an indication of a leak on the control side of the vacuum system. All the hoses have been replaced as well as the relays. Remaining existing components have tested OK. I have tested the system and it holds 22 " of vacuum - no leaks. Is a slight amount of movement 'normal', or have I missed something?

I do have some leakage on the heater/ air conditioning vacuum system. However, this is separate from the wiper control system so I don't think it would cause the door movement.

Any comments would be appreciated.

Dan Leslie

[Terry M.]

Re: 68 wiper door

When I start up my 68 after it has been sitting (no vacuum in system), the wiper door moves slightly about 1/4 inch up/down. I know this can be an indication of a leak on the control side of the vacuum system. All the hoses have been replaced as well as the relays. Remaining existing components have tested OK. I have tested the system and it holds 22 " of vacuum - no leaks. Is a slight amount of movement 'normal', or have I missed something?

I do have some leakage on the heater/ air conditioning vacuum system. However, this is separate from the wiper control system so I don't think it would cause the door movement.

Any comments would be appreciated.

Dan Leslie

Actually the leak in the HVAC system will effect the rest of the vacuum system. It is rather simple to temporarily block (clamp) the small line to the HVAC system as a test.

[Paul O.]

Re: 68 wiper door

Dan

The Heater and A/C vacuum is supplied by the Headlight and Wiper door system they are tied together. But you need to have 2 vacuum gauges one in the control side and one in the muscle side after the car is not run for a extended time period. To see what the difference in vacuum is between each system. The reason the door moves is the muscle side is greater then the control side at start up causing the door to move up till the control side catches up.