Bleeding Brakes
Discussion
Thought I'd change the fluid today but having done so I have no brakes at all. Tried again without the non-return valve thing, just a pipe in some old fluid and found lots of air in the fluid. Seems to be no fluid in the front section of the master cylinder even when its full to the brim. Is that why? Any ideas?
The brakes were fine before I started bleeding. I did have the mystery fluid loss over winter when most of the fluid disappeared (into the servo?)but after topping it up they worked OK without bleeding if a bit spongy but good and powerful. I did notice that when bv;leding the fomst I get the pedal down to the floor whereas the backs only seemed to give 3/4 travel on the pedal. Now its down to the floor all the time having bled 3 out of 4 wheels and still loads of bubbles.
I have bled each wheel at least twice more tonight and got lots of air out, especially the rears. Problem is after all this the pedal felt reasonable until I started the engine and then the pedal goes almost to the floor unless its pumped.Switch off and it goes hard. Is there a bleed valve on the servo that needs to be used or is it the dreaded servo that is going to have to be replaced? I have a horrible feeling I'm back to that afterall.
Appreciate you getting back. I would like to know form anyone if it is definitely the servo/master cylinder that has gone before embarking on getting it removed as I know it is a nasty/costly job to be entrusted to a specialist not a DIY task.
Strange thing is that before I bled the brakes they were fine apart from a bit more sponginess, but I put that down to the disappearance of fluid over winter.
During the bleeding yesterday it was worse. Every time we went round to a different wheel there was lots air in each line. But the real mystery was that when running the engine the pedal went to the floor first time and then after pumping got some brakes back. Could it be a seal has been reversed in the bleeding process? Even so I suppose it still means the servo has to come out.
Strange thing is that before I bled the brakes they were fine apart from a bit more sponginess, but I put that down to the disappearance of fluid over winter.
During the bleeding yesterday it was worse. Every time we went round to a different wheel there was lots air in each line. But the real mystery was that when running the engine the pedal went to the floor first time and then after pumping got some brakes back. Could it be a seal has been reversed in the bleeding process? Even so I suppose it still means the servo has to come out.
Sounds like the master cylinder as I am not loosing fluid when in use (just over winter) and the enyine sounds fine and the vacuum pipe is dry.
Was this not on a Griff then? Is it possible that the master cylinder can be removed without taking the pedal box out. The acces through the clutch cylinder coveris awful but if it possible please let me know how. Does the clutch cylinder have to come out first as I would suspect to access the brakes cylinder. I cant even see the bolts.
Was this not on a Griff then? Is it possible that the master cylinder can be removed without taking the pedal box out. The acces through the clutch cylinder coveris awful but if it possible please let me know how. Does the clutch cylinder have to come out first as I would suspect to access the brakes cylinder. I cant even see the bolts.
shpub said: If the pedal is going down when the engine is running that means the servo is working. To test it otherwise you need pressure guages and so on. If it was leaking it would more than likly screw up the engine running as well. They don't fail usually because their location stops them rusting through which is the usual way that they die.
I think you have a duff/leaking master cylinder. Either way it is bite the bullet time.
Steve
Cant even see the brake cylinder bolts in the access cover!
Would you by good enough to let me have the dismantle instructions for the brake master cylinder as I only bought the Bible (1st edition )at Duxford and there is nothing in it about this subject. For example I know you said s/column out, does this mean remove s/wheel and all stalk and horn wiring or unbolt at joint in footwell, also which bolts actually hold the pedal box in place?
Thanks
Chris
Steve,
Thanks for the details. I'm not sure who will do the job yet as the local guy isn't too keen and Fernhurst are too far away when you have almost no brakes to risk. They quoted 5 hrs so that gives me a pretty good idea. One point is how to drain the clutch system? Through the slave bleed valve no doubt; if so is it accessable by crawling underneath (without need for a 4 poster)?
I think most jobs on TVR are much worse than on other cars!
Chris
Thanks for the details. I'm not sure who will do the job yet as the local guy isn't too keen and Fernhurst are too far away when you have almost no brakes to risk. They quoted 5 hrs so that gives me a pretty good idea. One point is how to drain the clutch system? Through the slave bleed valve no doubt; if so is it accessable by crawling underneath (without need for a 4 poster)?
I think most jobs on TVR are much worse than on other cars!
Chris
I heard a new twist to this mystery yesterday. Apparently a similar problem on a 2.8 Capri revealed porous rubber brake hoses between the calipers and the pipework that would let air in but not fluid out. He actually changed the master cylinder and servo only to find the problem was still there. He then fitted stainless flexi hoses and the problem was solved. I was thinking of fitting flexis anyway as the car is 5 years old - maybe I should that next? Anyone like to comment on this one?
Latest on this saga is Fernhurst told me that I should not have bled the brakes using the pedal as this action will invariably stuff the master cylinder seals. They use a presure bleeder.
Since I have had the fluid leak over winter they said most likely the servos seals have been affected by fluid. They also said always best to change both according to TVR Factory warranty policy. Seeing as both have to come out of the car then its a pedal box out job.
So I am going to get a new servo and m/cylinder if I can find a TVR dealer who has them in stock, as these parts are TVR specific.
Chris
Since I have had the fluid leak over winter they said most likely the servos seals have been affected by fluid. They also said always best to change both according to TVR Factory warranty policy. Seeing as both have to come out of the car then its a pedal box out job.
So I am going to get a new servo and m/cylinder if I can find a TVR dealer who has them in stock, as these parts are TVR specific.
Chris
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