Bench Bleeding Master Cylinder
Thread Starter
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
Bench Bleeding Master Cylinder
I have a new (reman most likely) MC that I am installing. The original unit is in need of rebuild. It works, but the bowl has some rust deposits/sludge. I am bench bleeding the new one, and I cannot get a steady streem of fluid out the end. AND the new unit seems to be leaking around the rear pistion at the brake rod interface.
I am using a screw driver to plunge the piston and all I can get are spits of fluid out. I have tried both the old and the new MC's and get the same results.
The old unit does not appear to be leaking at the aft end of the piston.
Mark
I am using a screw driver to plunge the piston and all I can get are spits of fluid out. I have tried both the old and the new MC's and get the same results.
The old unit does not appear to be leaking at the aft end of the piston.
Mark
Le Mans Master
Joined: Nov 2000
Posts: 7,246
Likes: 21
From: Going too fast over the hill. Iowa
The trick is to connect a rubber/plastic line to the output port(s) and deliver the fluid output back to the reservoir. I use a wood dowel to pump them up.
Le Mans Master
Joined: Sep 2003
Posts: 8,934
Likes: 657
From: Norwalk ohio
2019 Corvette of the Year Winner
St. Jude Donor '15
Drifting
Joined: Jul 2005
Posts: 1,977
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From: Putnam Valley, New York. Amateur Radio Operator K2NS
"new" Master Cylinder
RON
Thread Starter
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
Ok, I will get the kit. Second question, are new seals available. I pulled the old one apart, and I think if I could aquire the new seals I would be in business.
I could rob the seal out of the "new" MC, but there is a reason that it is leaking as well. The old MC, as mentioned did not leak out the back but the seal is very old and brittle.
Can you push the piston to far forward when pumping it for the bench bleeding process? Is there a range of travel that if I went past would make the rear seal leak?
Mark
I could rob the seal out of the "new" MC, but there is a reason that it is leaking as well. The old MC, as mentioned did not leak out the back but the seal is very old and brittle.
Can you push the piston to far forward when pumping it for the bench bleeding process? Is there a range of travel that if I went past would make the rear seal leak?
Mark
Thread Starter
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
The new MC (From Ecklers) was bored WAY out. The aft seal slides in and out not problem. It fits is way to loose IMO. I took the seal (on the piston) and tried to put it in the old MC and it will need some guiding to get in.
The bore of the old MC looks ok, no damage or corrosion. Will it be OK to use the new seal on it without honing it out?
Mark
The bore of the old MC looks ok, no damage or corrosion. Will it be OK to use the new seal on it without honing it out?
Mark
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Burning Brakes
Joined: Dec 2002
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From: Hasbrouck Heights NJ
Thread Starter
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
Magic I think I remember reading that on a thread a sometime about not using a screwdriver. I found a dowel to do the job. As I put the "New" MC back in the box I noticed a crumpled piece of paper in the bottom. It said.
WARNING: Due to the OEM type seal, do not attempt to bench bleed this Master Cylinder. Pressure of Vacuum Bleed only. ????
I robbed the new seals off the new MC, and installed them on the old MC. The fit was tight; I had to use a feeler gauge to feed the lip of the seal into the cylinder bore. Prior to assembly I put some small patches of Scotch Brite pad on the shoes of my brake hone and polished the cylinder. I used siphon fed Alcohol to clean the cylinder and orifices.
Here is my original MC, or the one that was on the car when I purchased it. The piston on the left is the one out of the new MC. The piston on the Right is the one that came out of the old MC.
Mark
WARNING: Due to the OEM type seal, do not attempt to bench bleed this Master Cylinder. Pressure of Vacuum Bleed only. ????
I robbed the new seals off the new MC, and installed them on the old MC. The fit was tight; I had to use a feeler gauge to feed the lip of the seal into the cylinder bore. Prior to assembly I put some small patches of Scotch Brite pad on the shoes of my brake hone and polished the cylinder. I used siphon fed Alcohol to clean the cylinder and orifices.
Here is my original MC, or the one that was on the car when I purchased it. The piston on the left is the one out of the new MC. The piston on the Right is the one that came out of the old MC.
Mark
