M/C leak.
12-14-2009, 12:40 PM
#1
Drifting
Thread Starter
M/C leak.
Hey, Before I forget merry Christmas to all on the CF.
I've noticed a small brake fluid drip (leak) what looks like it's coming from where the M/C bolts into the power brake booster then follows down to the bottom of the booster then drips on the floor.
My 70 coupe is up on jacks and has fresh fluid in the M/C as of last month. The last time I ran the car and checked the brake pedal it had great pressure. The pool of BF on the floor will be the size of a quarter after a weeks time.
Both nuts holding the M/C to the P/B are pretty darn tight but I could honk down some more on them but dont think it wise to do so.
Is there a gasket or o-ring between the M/C and the power booster?
I'm betting I'm going to have to pull the M/C at some point to stop this leak. Is this correct? Any Ideas what I need to do?
I dont have a problem getting a new M/C if that is going to make it easy for me to do.
I tried to discribe the leak the best I can & as you might of guessed I'm not familure with the M/C.
I've noticed a small brake fluid drip (leak) what looks like it's coming from where the M/C bolts into the power brake booster then follows down to the bottom of the booster then drips on the floor.
My 70 coupe is up on jacks and has fresh fluid in the M/C as of last month. The last time I ran the car and checked the brake pedal it had great pressure. The pool of BF on the floor will be the size of a quarter after a weeks time.
Both nuts holding the M/C to the P/B are pretty darn tight but I could honk down some more on them but dont think it wise to do so.
Is there a gasket or o-ring between the M/C and the power booster?
I'm betting I'm going to have to pull the M/C at some point to stop this leak. Is this correct? Any Ideas what I need to do?
I dont have a problem getting a new M/C if that is going to make it easy for me to do.
I tried to discribe the leak the best I can & as you might of guessed I'm not familure with the M/C.
12-14-2009, 12:45 PM
#2
Drifting
Thread Starter
Hey, Before I forget merry Christmas to all on the CF.
I've noticed a small brake fluid drip (leak) what looks like it's coming from where the M/C bolts into the power brake booster then follows down to the bottom of the booster then drips on the floor.
My 70 coupe is up on jacks and has fresh fluid in the M/C as of last month. The last time I ran the car and checked the brake pedal it had great pressure. The pool of BF on the floor will be the size of a quarter after a weeks time.
Both nuts holding the M/C to the P/B are pretty darn tight but I could honk down some more on them but dont think it wise to do so.
Is there a gasket or o-ring between the M/C and the power booster?
I'm betting I'm going to have to pull the M/C at some point to stop this leak. Is this correct? Any Ideas what I need to do?
I dont have a problem getting a new M/C if that is going to make it easy for me to do.
I tried to discribe the leak the best I can & as you might of guessed I'm not familure with the M/C.
I've noticed a small brake fluid drip (leak) what looks like it's coming from where the M/C bolts into the power brake booster then follows down to the bottom of the booster then drips on the floor.
My 70 coupe is up on jacks and has fresh fluid in the M/C as of last month. The last time I ran the car and checked the brake pedal it had great pressure. The pool of BF on the floor will be the size of a quarter after a weeks time.
Both nuts holding the M/C to the P/B are pretty darn tight but I could honk down some more on them but dont think it wise to do so.
Is there a gasket or o-ring between the M/C and the power booster?
I'm betting I'm going to have to pull the M/C at some point to stop this leak. Is this correct? Any Ideas what I need to do?
I dont have a problem getting a new M/C if that is going to make it easy for me to do.
I tried to discribe the leak the best I can & as you might of guessed I'm not familure with the M/C.
12-14-2009, 12:55 PM
#3
Pro
Member Since: May 2003
Location: London England
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If you're sure the fluid is coming from where the MC meets the booster then it's most likely the rear seal on the MC.
This can fail and you'll still have good brakes (until the fluid runs out) because all it does is keep the fluid in the cylinder, it's not a pressurized seal.
If it is that you should think about changing it ASAP as fluid may be leaking into the booster and can rot the booster diaphragm.
Hope that makes sense
This can fail and you'll still have good brakes (until the fluid runs out) because all it does is keep the fluid in the cylinder, it's not a pressurized seal.
If it is that you should think about changing it ASAP as fluid may be leaking into the booster and can rot the booster diaphragm.
Hope that makes sense
12-14-2009, 01:31 PM
#4
Le Mans Master
If you're sure the fluid is coming from where the MC meets the booster then it's most likely the rear seal on the MC.
This can fail and you'll still have good brakes (until the fluid runs out) because all it does is keep the fluid in the cylinder, it's not a pressurized seal.
If it is that you should think about changing it ASAP as fluid may be leaking into the booster and can rot the booster diaphragm.
Hope that makes sense
This can fail and you'll still have good brakes (until the fluid runs out) because all it does is keep the fluid in the cylinder, it's not a pressurized seal.
If it is that you should think about changing it ASAP as fluid may be leaking into the booster and can rot the booster diaphragm.
Hope that makes sense
12-14-2009, 02:59 PM
#5
Team Owner
Member Since: Jun 2000
Location: Southbound
Posts: 38,928
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12-14-2009, 03:15 PM
#6
Race Director
Are you sure the fluid is not coming from the 2 fittings and running backwards ?
Also its very common when the level is high for the fluid to leak out the back of the cap and run down.
If you haven't already run your finger behind the cap and under the side fittings and see if its wet.
Also its very common when the level is high for the fluid to leak out the back of the cap and run down.
If you haven't already run your finger behind the cap and under the side fittings and see if its wet.
12-14-2009, 07:46 PM
#7
Drifting
Thread Starter
Ok, thanks guys for all the info.
Roger, are you refering to the fittings on the side? No, I can see where the leak is seeping from and its at the M/C mounting bolts on the brake booster seeping down from in front of the booster traveling across the bottom of the booster till it drips off.
Thanks Mike, I new I was in need for some change or repair but didnt know for sure the problem or how to attack it.
Your right Toddalin, I have a snail track of blisterd paint from where the M/C mounts to the booster to the bottom back of the power booster.
Golden, Thanks for that bit of info. You just confirmed my nightmare. also didnt know that it would leak into the power booster.
I've been researching this M/C quest for most of the afternoon. I thought I could rebuild the M/C thats on the car and so not having ever done that and or never have even bench bleed a M/C think it's best to install a new M/C.
More questions to come. Thanks.
Roger, are you refering to the fittings on the side? No, I can see where the leak is seeping from and its at the M/C mounting bolts on the brake booster seeping down from in front of the booster traveling across the bottom of the booster till it drips off.
Thanks Mike, I new I was in need for some change or repair but didnt know for sure the problem or how to attack it.
Your right Toddalin, I have a snail track of blisterd paint from where the M/C mounts to the booster to the bottom back of the power booster.
Golden, Thanks for that bit of info. You just confirmed my nightmare. also didnt know that it would leak into the power booster.
I've been researching this M/C quest for most of the afternoon. I thought I could rebuild the M/C thats on the car and so not having ever done that and or never have even bench bleed a M/C think it's best to install a new M/C.
More questions to come. Thanks.
12-14-2009, 09:01 PM
#8
Drifting
Thread Starter
From my research today I've found that I'd be best to change out the M/C completly instead of trying to rebuild the exsisting M/C with my lack of experence and time.
Are all or most stock brake power boosters going to match up to the master cylinders.
In other words I've noticed that some M/C are a one inch bore and others are 1 1/8" bore.
Is this the ID of the piston inside the M/C? and will either one mate up to the power booster.
I looked around at a few sites for M/C for this car and narrowed it down to what should be a 1 1/8" M/C GM # 5460346. paragon has this M/C and seems to be correct for the power booster. The current M/C on the car now is one that has number 29969 made in usa and it's also at paragon but does not decribe the bore ID.
Is there any other info I missing before I order this M/C.
Thanks Again.
Are all or most stock brake power boosters going to match up to the master cylinders.
In other words I've noticed that some M/C are a one inch bore and others are 1 1/8" bore.
Is this the ID of the piston inside the M/C? and will either one mate up to the power booster.
I looked around at a few sites for M/C for this car and narrowed it down to what should be a 1 1/8" M/C GM # 5460346. paragon has this M/C and seems to be correct for the power booster. The current M/C on the car now is one that has number 29969 made in usa and it's also at paragon but does not decribe the bore ID.
Is there any other info I missing before I order this M/C.
Thanks Again.
12-15-2009, 08:06 AM
#9
Supporting Vendor
It sounds like you've got the correct information on the M/C. You can get either a replacement or a Delco-Licensed reproduction. The replacement will be less expensive, but the reproduction will have the correct casting numbers and stamps. Let me know if I can help.
