740 Cruise Control Easy Fix - vacuum servo actuator

[Peter Coutts]

I will share this easy fix as others may run across the same issue:

My 1987 740 Cruise control just stopped working with no warning. After getting some hints off this forum and others I started on the task of tracking the problem....first item I chased were the vacuum lines. What I actually found was a tear/wear hole in the rubber diagram on the vacuum servo actuator that sites just behind the throttle cables...cruise cable connects to the servo actuator.
I took the servo and cable off very easily by undoing one 13mm bolt...cleaned the part and sanded around the tear in the rubber diaphram. I then repaired the hole using automotive "Goop" sealant...similar to silicon sealant as it cures quickly and remains pliant.
Replaced the servo very quickly and took car for a run. The cruise has been working with no problems. Even if the sealants fails I can put more on or actually replace with a new servo part which is about $125 CDN not including labour. The longest part of the repair was cleaning the part.