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1970 Olds 442 Developed Mushy Brakes(Power Front Disc)
On the way to a show on Saturday after I stopped for breakfast I lost what is normally a pretty nice feeling pedal. I was close to the show so finished off the drive just allowing extra stopping distance. It wasn't feeling unsafe just went mushy. Parked it and walked around looking at cars while it cooled down a bit under the hood.
-Checked fluid and the front reservoir is low.
-Since front was low I inspected front calipers and inside wheels. No fluid
-Where the master meets the booster it is damp and looks like some fluid might have been dripping down there and the paint is bubbling slightly
So it sounds like I might have a leak inside the master that is leaking into the booster. At least from my experience this might be the case.
Anything else to check? And recommendation on where to buy these parts? And once acquired anything special to bleed this setup? None of my BMWs have bleeders on the resevoir/master. I'd just use a power bleed at the calipers and then do a couple manual activation per corner.
On the way to a show on Saturday after I stopped for breakfast I lost what is normally a pretty nice feeling pedal. I was close to the show so finished off the drive just allowing extra stopping distance. It wasn't feeling unsafe just went mushy. Parked it and walked around looking at cars while it cooled down a bit under the hood.
-Checked fluid and the front reservoir is low.
-Since front was low I inspected front calipers and inside wheels. No fluid
-Where the master meets the booster it is damp and looks like some fluid might have been dripping down there and the paint is bubbling slightly
So it sounds like I might have a leak inside the master that is leaking into the booster. At least from my experience this might be the case.
Anything else to check? And recommendation on where to buy these parts? And once acquired anything special to bleed this setup? None of my BMWs have bleeders on the resevoir/master. I'd just use a power bleed at the calipers and then do a couple manual activation per corner.
It could also be a leak between the front and rear pistons in the M/C, but either way, it's time for a new M/C.
If you suspect that brake fluid got in the booster I'd definitely pull it & check it. When I did the disc brake conversion on my '68 I was replacing the booster anyway but the old one had quite a bit of brake fluid in it. I don't think that brake fluid would hurt the rubber parts inside the booster but they're cheap enough I'd put a new one on along with the master.
Again, the M/C has to be replaced no matter what. Once you pull it off, it will be obvious whether or not there is fluid leaking out the back. The seal between the M/C and booster should prevent fluid from being sucked into the booster. Usually there is a wet trail down the outside of the booster under the back of the M/C when this happens.
Check the condition of this seal when the M/C is off.
As for the reverse bleeder systems, why in the world would you want to push old brake fluid contaminated with worn seals back into your new master cylinder. I've never been able to understand why that system makes any sense.
Copy. That was my plan. I looked at prices and even the nicest/best ones are not too much. With the simple system replacing in the garage should be quite easy...
Now if only I owned a single standard tool. A long time of BMW ownership means I just have a lot of metric and a bunch of 10mm and 13mm as they go missing...
Copy. That was my plan. I looked at prices and even the nicest/best ones are not too much. With the simple system replacing in the garage should be quite easy...
Now if only I owned a single standard tool. A long time of BMW ownership means I just have a lot of metric and a bunch of 10mm and 13mm as they go missing...
Not only do you need SAE tools for this job, you NEED a set of flare nut wrenches to avoid collateral damage.
The line wrenches Joe posted will certainly come in handy as you know . I spray the fittings with liquid wrench the day or two before I start wrenching on the brake lines, depending on corrosion. I hate twisting lines then having to replace them.
Might as well flush the whole brake system while you're at it. Brake fluid absorbs moisture and causes rust, might be time to start fresh, the front hoses to the calipers can also deteriorate over time. Reverse bleeding works great, one man operation, best way to get rid of air.
The line wrenches Joe posted will certainly come in handy as you know . I spray the fittings with liquid wrench the day or two before I start wrenching on the brake lines, depending on corrosion. I hate twisting lines then having to replace them.
Yah. I'd do that for sure.
Originally Posted by dragline
Might as well flush the whole brake system while you're at it. Brake fluid absorbs moisture and causes rust, might be time to start fresh, the front hoses to the calipers can also deteriorate over time. Reverse bleeding works great, one man operation, best way to get rid of air.
Of course. Definitely would bleed and replace all the fluid.
Get chew one of these(see links). Quick...easy. I can do all 4 bleeders in 30 mins or less. Dont forget to get the correct master cylinder adapter. I see they have upgraded the pump hose with a quick-disconnect. Make sure the adapter comes with the mating male end. I have several adapters for each vehicle I own. I use small surgical hose(amazon) attached to the bleeders down into a cup to recover the waste fluid.
Always use the correct fluid. Make sure its fresh and of high quality. Never store the fluid in the motive pump. Store everything in a clean dry environment. Never use fluid thats been in an open container with fluctuating ambient conditions. It does absorb moisture just sitting in the container same for your brake system.
I bleed all of my vehicles brakes on a biennial or triennial basis regardless of miles. Thats why my 95 Jeep GC has its original calipers. Sure its soft lines have been replaced as those lines should be replaced every decade or so as a safety item.
How many people do this...only the few ****-retentives like myself..
Clean fresh fluid and clean tools equals a happy safe long lasting hydraulic brake system.
I actually prefer the Vacula bleeder, same idea but it uses shop air to create a vacuum. I've never had to bleed more than one time, nor do I even have to bench bleed the master cylinder. This just sucks all the air right out of the system. Best tool I've ever bought.
I actually prefer the Vacula bleeder, same idea but it uses shop air to create a vacuum. I've never had to bleed more than one time, nor do I even have to bench bleed the master cylinder. This just sucks all the air right out of the system. Best tool I've ever bought.
Do you have to do anything to prevent air getting around the bleeder screw?
Do you have to do anything to prevent air getting around the bleeder screw?
Air that leaks around the bleeder threads immediately gets sucked into the unit. Yeah, the fluid coming from the screw into the bleeder unit has air bubbles from this. Who cares? The air flows to the lowest pressure area, which is inside the unit. It can't physically flow upstream into the brake system.
Thanks Joe you kind of answered my next question. One last one - if air bubbles are still in the line, how do you know when you got all the air out of the brake system?
Thanks Joe you kind of answered my next question. One last one - if air bubbles are still in the line, how do you know when you got all the air out of the brake system?
I just run the bleeder until it sucks about 1/4 of the fluid out of the M/C reservoir, then go on to the next wheel. Probably more like 1/2 if the lines are empty or I want to completely flush the system. Actually, you can hear the difference in the sucking sound. The sound is different if there is a lot of air coming out vs. just the leakage around the bleeder screw.
I got mine used at the Long Beach swap meet, probably 20 years ago. No one knew what it was - not even the seller. I paid $15.
I need to get out to more swap meets! Burls creek is only spring and fall here in Ontario, not as good as it was years ago.
$15 bucks... , Oh, I bet you felt awful taking it off his hands for a steal eh haha!
Me too. Or DOT5 in my track cars. I was asking basically if the difference in fluid is OK for the older vehicle. IE won't break stuff down or the viscosity is too low.
August 26th, 2018, 07:49 PM
