Stiff breaks With running engine ---> Bleed problem rear *Fixed

[Tim_de_Ridder]

Hey all

I am working on the brakes for quite some time now and have run into multiple issues

car specs:
- Rover P6 V8
- Duel line brake system

previous worked on:

- Replaced the master cilinder <--- could not be saved
- Rebuild the Slave Servo ---> rubbers and such
- Replaced rubbers in brakes
- Replaced flexible brake lines
- Replaced some of the brake lines on the rear

that sums it up
______________

I tried bleeding the brakes ---> first front left [driver side] and the rear at the same time --> brakes at the back did get small amounts of fluid after bleeding for about 15 min continued with the front right and the rear both front brakes are fully working but are getting stiff and staying in that postion for some time ---> removed the slave servo and after adding some lube tried bleeding again same result ---> tried with engine on slave servo starts making sounds and then again stiff brakes

perhaps any of you having experience with this and or suggestion what to try next

Would love to hear it

Tim.



*Fixed it ----> problem being that the diaphragm [the big rubber seal where the 2 vacuum compartments meet was not placed right after adjusting the seal between the 2 compartments the brakes worked well in the test drive wanted to thank all of the people who helped me out with this

 

[sdibbers]

I think you’re doing it in the wrong order. You should start at the point furthest from the master cylinder and move closer. Also, the factory method is to open the bleed valve then pump the pedal three times rapidly holding down on the last stroke, then close valve, release pedal, and repeat. Keep an eye on brake fluid level in the reservoir while doing this.

I would also look at the pedal trunnion adjustment. If the push rod is too extended (High pedal) the servo will activate and give you the symptoms you describe.

 

[Tim_de_Ridder]

Ah thanks for the reply 'sdibbers' i will start at the rear and move to the front left and then right with the method you just suggested

 

[Bougsy]

Had a similar problem with mine (but single circuit brakes) when I fitted a new seal kit to the servo. The tiny piston in the air control valve was sticking in the bore (I think the new seals are manufactured a bit over size). When the piston sticks it still allows pressure from the servo to pass into the system and hold the brakes on slightly, not solidly but enough to make them bind. I tried all sorts from rubber grease lubrication to even using wet & dry paper on the seal to try and reduce it a bit. Gave up in the end and got a complete reconditioned servo which cured it.

 

[Tim_de_Ridder]

Thanks for the info 'bougsy' I will try to bleed the car again later today

perhaps another kit with better rubber seals I heard people on the E type forums talk about this aswell

 

[Vern Klukas]

I'm starting to see lots of trouble with oversized repo seals, not only in this forum but elsewhere.

Yours
Vern

 

[Tim_de_Ridder]

I may have found the original one and the one from the kit

there is a big difference / rubber cup nr 20

 

[Tim_de_Ridder]

Little update on the brakes bleeding succesfull --- thanks to the tip from "sdibbers" ---> next thing is that the brakes go stiff when running the engine without running engine its possible to press multipole times but with the engine on it goes stiff in an instant

perhaps the brake booster?

 

[roverp480]

I had a similar issue with my P4 Rover, it was the servo sticking on, which was keeping pressure on the brakes. Eventually after a number of rebuilds fitted a new servo and the problem was solved.

 

[Tim_de_Ridder]

'roverp480' thanks for your comment seems like i have to take a new servo inconsideration

 

[classicalgreen]

had my brakes stick on after MOT test . drove short distance home thinking was engine. issues . when stopped smoke from brakes . turn dout. pressure was he'd inside servo unit but as only few months ok d( exchange ) seemed odd. transpired there a small inner spring that if rakes not used regularly can rust ? and adhere keeping pressure in system. now using car at least once every 3-4 weeks and no further brake sticking issues!

 

[Tim_de_Ridder]

Thanks for the comment "classicalgreen" in this instant all the parts of the servo have been replaced but i will keep that tip in mind if i get it to work

 

[Barten]

I had a similar problem with my car that also has a dual brake system. I had taken the brake servo apart and when putting it together I made a mistake when trying to attach the locking tab as described in the manual. The result was locked brakes when the engine ran. I fixed that problem, but still had problem bleeding therear brakes. In the end I had to open each connection in the brake system on the way aft and finally i got pressure all the way. I blame airpocket in the 5 way valve. Now it is finally ok.

 

[Tim_de_Ridder]

I had a similar problem with my car that also has a dual brake system. I had taken the brake servo apart and when putting it together I made a mistake when trying to attach the locking tab as described in the manual. The result was locked brakes when the engine ran. I fixed that problem, but still had problem bleeding therear brakes. In the end I had to open each connection in the brake system on the way aft and finally i got pressure all the way. I blame airpocket in the 5 way valve. Now it is finally ok.

"Barten" Thanks for the comment question: where is that so called locking tab could you describe it so i could take a look at it

thanks in advance

i added some photo's

 

[Barten]

It is number 29 on the drawing. I did not have the right name on it. It is the key. I had intalled it incorrectly so the slave cylinder piston was not attached to the servo.

 

[Tim_de_Ridder]

It is number 29 on the drawing. I did not have the right name on it. It is the key. I had intalled it incorrectly so the slave cylinder piston was not attached to the servo.

Thanks again for the comment "Barten" i will look into it right away

 

[Tim_de_Ridder]

Hmmm its instaled correctly removed it placed it back but no difference ---> brakes work without the engine running or when the
hose from the engine intake is not attached [brakes are not assisted then]

any other sugestions?

 

[Tom W]

Have you replaced/rebuilt the valve that actuates the servo?

 

[Tim_de_Ridder]

Thanks for your comment "Tom" could you describe which valve

 

[Tom W]

If your dual circuit system is the one I’m thinking of, the valve is on the end of the master cyl. A white circular assy, about 3” dia. It’s similar to the setup used by Jaguar from the mid 60s. Sticking reaction valves and dragging brakes are common problems in Jag circles.