Recently purchased a 1969 Mark III. It is in fair condition, with low mileage and a beautiful interior. However, the power steering has proved problematic. The pump seems to put out the required pressure only at higher rpm (1500+). The hydraulically operated windshield wipers will move laboriously at idle, but seem to move as intended at higher rpm. Is this a symptom of a failing pump? I have flushed the system, replacing the fluid with ATF as recommended. I have also attempted to bleed air from the system by turning the steering wheel lock to lock with the engine off. The wipers operate consistently at the same speed irregardless of the position of the wiper control knob as well. Could these problems be related?
Another possibly related problem is a seeming wandering of the vehicle above 45 mph; this wandering is severe enough that it renders the vehicle unsafe to drive, in my opinion. Could this be related to the steering system components, such as the rack or rag joint? Or is it indicative of an alignment/suspension/tire problem as I have read?
Greetings Cody –
From your description of what you have done so far to remedy the high steering effort at low rpm I think that it would be a good idea to have your pump taken apart and inspected for worn internal parts. This is not an uncommon failure and at the same time new seals would be installed. We do offer a rebuilding service for these pumps if necessary. The system also has a hydraulic filter that is located in the reservoir that should be inspected.
Low pump pressure will of course affect the wiper operation but a cable adjustment is provided for the hydraulic wipers where the fluid lines go through the firewall. Access is gained by loosening the small panel and moving it forward to expose this adjustment. The cable adjustment and its operation are easy to understand and the hydraulic lines do not need to be disconnected to perform the adjustment.
Your description of the unsafe steering and wandering condition leads me to believe that a complete inspection of the front suspension including the springs, rag joint, steering linkage and steering box will be a necessary and an excellent suggestion for you to have done for your newly acquired Mark III. At the same time the tires should also be inspected for age deterioration and broken belts etc. Several components may need to be replaced and the front end will need to be re-aligned. If the above is done correctly the car will handle like new and be a joy to drive.