Skip to main content

Replies sorted oldest to newest

Thanks guys. I use the vacum pump on the caliper bleed screw to draw the old fluid out while keep topping off with new fluid and drawing that fluid through until I see the new clean fluid come through. Has worked pretty good in the past on my cars, although on the front right caliper on my group 4 I remember I had problems drawing the new fluid through. Not sure but maybe I didn't top off that well when doing that side and I think possibly air got in the line. But resolved it by pressing the pedal method on that caliper.

Just watched a youtube on the use of the Motive Products fluid change and that does look like an excellent thing to have; but on my red 5S it looks like that may not work since I don't have a screw on reservoir to be able to make pressure. Looks like it may work on the clutch fluid change though.

Pantera GT5S by JanDaMan, on Flickr
Last edited by does200
The brass 'safety' shuttle valve mounted below the power booster can and has shifted to one end of it's valve body during vigorous brake bleeding. This severely restricts or even shuts off fluid flow to one pair of brakes. DeTomaso, alone among car manufacturers that use these valves, included no internal return springs for the movable shuttle. So if the shuttle moves too far in a used valve (which always has varnish buildup inside), the shuttle may become so firmly wedged in an end that you will wind up with essentially NO brakes at one end of the car!

The shop fix is to disconnect the hydraulic lines, remove the valve, inspect for shuttle position and if required, blow into the outlet ports with an air compressor, making allowances for the spray of paint-removing brake fluid that will also happen. The shuttle position can be seen thru the hole for the stoplight switch if the valve is removed from the car. As installed in a Pantera, with the stoplight switch valve port facing the firewall & underneath the booster, even a lit inspection mirror doesn't work. The air pressure thing can be done in the car, but you WILL get brake fluid spraying around, and the shuttle may move back to center- or move too far, to stick at the other end of its travel.

All this is among several reasons I suggest removing that valve and put it on a shelf somewhere, far away from the car. Re-plumb the system without it so the brake master cylinder still supports two separate front & rear brake systems, as req'd by the U.S. DOT since 1968 for safety.
bosswrench, after syphoning old fluid from the reservoir and pouring new fluid in, I was just going to use my vacuum pump at each wheel to pull fluid through and keep topping off at the reservoir so air doesnt get sucked in. Do you think that method would present any problems such as what you describe? Just fluid change is all I was going to do at the moment.

Add Reply

Link copied to your clipboard.