Brake Bleeding Trouble

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pawlusultana
Posts: 3
Joined: Fri Apr 19, 2019 2:29 pm

Brake Bleeding Trouble

Post by pawlusultana »

Hello everyone,

I have just replaced a leaking brake master cylinder on a 330 GT Series 1(1964) and I’m having trouble bleeding the system.

I have followed the original workshop manual for the procedure with having the right clearance between the pushrod and master, as well as the bleeding sequence and the filler caps closed. I tried multiple times with the vacuum bleeder and also the old school way with an assistant pumping the pedal but to no avail. The first stroke on the pedal goes down completely and then builds up between the second and third stroke. What surprised me is that while vacuum bleeding the front servo I was smelling fuel, so I think that the hydraulic cylinder in the front booster is sucking air through the vacuum pipe connected to the inlet manifold. I also took the car for a small drive and the fluid in the front reservoir became darker, and that is after the whole system was bled multiple times with new fluid.

Are there any particular tests that I should do before sending the booster to a specialist?

Thanks!
PS
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tyang
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Re: Brake Bleeding Trouble

Post by tyang »

Hi PS,

These remote booster set ups are tricky to bleed and I have had pretty good success reverse bleeding by sending fluid back through the bleeders. Air gets trapped in the brake lines, and there is often not enough volume of fluid to force it out by the brake master. Once I know the air is gone, a regular brake bleed with a helper at the brake pedal will work fine.

It does sound, however, you may also have a problem with the servo.

Good luck!

Tom
'63 330 America #5053
tim
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Joined: Tue Sep 03, 2002 2:48 pm
Location: sacramento, ca

Re: Brake Bleeding Trouble

Post by tim »

Greetings... I use a home made pressure bleeder bleeding first from reservoir through m/c to booster. Next, through the booster. Next out to the wheels. A couple of quarts of brake fluid and all is well. I am using Lockheed boosters rather than the original Bonaldi because at that time I couldn't find a rebuilder. When I asked Bill Rudd about rebuilding he said no one bothered since new ones were available. I think some day I shall try reverse bleeding. Tom, do you bleed the circuit from the bleed nipples back to the reservoir or make stops along the way.

Tim
1964 330GT 5769 -the big yellow taxi 61&66 Morgan +4's Daimler SP250 and some other dull stuff plus a brand new Mini Cooper S Clubman JCWS
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tyang
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Re: Brake Bleeding Trouble

Post by tyang »

tim wrote: Fri Nov 20, 2020 1:14 pm Greetings... I use a home made pressure bleeder bleeding first from reservoir through m/c to booster. Next, through the booster. Next out to the wheels. A couple of quarts of brake fluid and all is well. I am using Lockheed boosters rather than the original Bonaldi because at that time I couldn't find a rebuilder. When I asked Bill Rudd about rebuilding he said no one bothered since new ones were available. I think some day I shall try reverse bleeding. Tom, do you bleed the circuit from the bleed nipples back to the reservoir or make stops along the way.

Tim
Hi Tim,

With the SI 330s, I have to use several methods. I find air often gets trapped in the booster, and there are two bleeder screws on the Bonaldi units that allow air to escape. When reverse bleeding, I try to go all the way back to the reservoir from the calipers with fluid. I will also get a short piece of tubing and go from the bleeder on the servo back to the reservoir to see if small bubbles push through the lines as the pedal is depressed. Each car seems to respond differently, so my techniques change from car to car. The problem with the the Series I cars is there is one master cylinder, and two separate servos, so there are a lot places air can get trapped.

Tom
'63 330 America #5053
Steve Meltzer
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Re: Brake Bleeding Trouble

Post by Steve Meltzer »

Back in the summer and fall of '19 i had a helluva time bleeding the brakes on my GTC ...which I'd done easily many times before using a modestly powered medical vacuum setup called a Gomco. Proved it was the MC and sen the MC out and twice the return repairs also failed. About that time a master Ferrari mechanic, Terry Myr, came to Houston, on another mission and he too failed and did it by pressurizing the system!
Got with Tom Y and bit the $1000 bullet for a new brake MC from Italy, installed by Terry in his shop and it too failed!!! Now Terry thought he could machine the MC to make it work, but it was a $1000 gamble...no returns if machined....I held my breath and Terry machined it perfectly, bled easily and no problems since. Bottom line: even new, expensive and correct stuff maybe faulty. I don't blame Tom, of course, and he offered to take it back if still a virgin, but Terry and I took the risk, and it worked. Whew! s
steve
meltzer, "“With a Ferrari, whatever it is, it’s a $1000. If that’s what it is.”"
'66 330 GTC, '72 Daytona-red, did they make any other colors?
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