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Tips
Tips

TR6 Replacing old brake fluid and bleeding brakes

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poolboy said:
Maybe try this:
Put the brake lines back on the master cylinder and have someone pump the brake pedal while you observe the fluid in the reservoir. Do you see air bubbles or notice the level changing while the pumping is going on ?
Click to expand...
Did that this morning and nothing at all... no fluid, no air bubbles
 
I'd probably remove it and bench test it...maybe a seal needs replacing.
 
poolboy said:
Maybe try this:
Put the brake lines back on the master cylinder and have someone pump the brake pedal while you observe the fluid in the reservoir. Do you see air bubbles or notice the level changing while the pumping is going on ?
Click to expand...
I already tried that and still nothing!
 
OK, I found the culprit. I removed the master and found that the piston on the master is pushed in and It did NOT return. I just ordered a replacement master cylinder. It pisses me off that a simple fluid change resulted in getting a new master.
 
poolboy said:
Do you know the brand of the old one ?
Click to expand...
Yes, it is the Lucas one. I've tried tapping with a wooden hammer to get the piston to move back to the front of the bore but no luck.
All of the normal vendors do not have the Lucas (made by TRW) in stock so I had no choice but to get the less expensive one.... I hope it will do the job. I would like to rebuild the one I have but I can't see how I'm going to move the piston back. At this point I must get the car done and back on the ground in the next week or so. Hopefully I'll have the new master by Saturday and I'll get it installed and bled but this time I intend to use a vacuum pump.
 
poolboy said:
The tipping valve might be whats holding the piston stuck
Click to expand...
I intend to investigate that after I get the replacement in and working. If I wasn’t under a timeframe to get it done I would do that now. Thanks again for your timely and informative posts.
 
I ordered a new brake master cylinder late yesterday. I just checked the suppliers website and tonight the price has increased by ~25%.
That's a hefty increase!
 
Gliderman8 said:
OK, I found the culprit. I removed the master and found that the piston on the master is pushed in and It did NOT return. I just ordered a replacement master cylinder. It pisses me off that a simple fluid change resulted in getting a new master.
Click to expand...
Here’s a pic of the master cylinder that failed.
The piston is down about 2 inches.
The retaining collar holding tipping valve in is going to be hard to remove.
The replacement is supposed to be here today.
 

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I am a bit of a nut when it comes to installing NEW master cylinders. These are available and cheaper than any crash.
If yours is of an unknown age I suggest it is smart money spent.
In any race car I have ever seen or been close to, they all had FRESH brake master cylinder(s). There is a damned good
reason. There is a racing adage "don't be that guy" referring to fundamental judgement errors. I have lots of stories
of neglected master cylinders (on the street) that wound up in my Collision Repair Shop.
I like to power bleed a new system , it is inexpensive to buy a kit that pulls the fluid down to the wheels one at a time.
Mad dog
 
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mctriumph said:
I am a bit of a nut when it comes to installing NEW master cylinders. These are available and cheaper than any crash.
If yours is of an unknown age I suggest it is smart money spent.
In any race car I have ever seen or been close to, they all had FRESH brake master cylinder(s). There is a damned good
reason. There is a racing adage "don't be that guy" referring to fundamental judgement errors. I have lots of stories
of neglected master cylinders (on the street) that wound up in my Collision Repair Shop.
I like to power bleed a new system , it is inexpensive to buy a kit that pulls the fluid down to the wheels one at a time.
Mad dog
Click to expand...
Received the new master cylinder yesterday.
Going to try and install it today, but it’s in the 20’s here so a little too cold for me.
I also intend to use a vac to bleed.
 
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