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I have been searching the forums and the web for anyone who may have experienced a leak in the brake system.
The leak appears to originate somewhere around the master cylinder but I cannot locate the exact spot.
I noticed the problem when I started the car and it began to generate white smoke in the drivers side. I also knew it was not oil or ATF because brake fluid smells different. I pulled the cover by the master cylinder (MC) and could see an area that was wet under the MC.
I may have a reservoir leak but I cannot pinpoint at this time. Photos will be provided later if I can take some that show the issue.
If anyone has any experience in this area, please chime in...I do know they are expensive and I do know that Toyota and Lexus recalled several models for a leaky reservoir.
If you indeed are showing dropping brake fluid reservoir levels, and the area under the MC is wet, I agree with getting a rebuilt MC. I've used rebuilt MC's over the years and never had a problem. I even remember as a teenager watching my Dad rebuild MC's and wheel cylinders before rebuilts were readily available (hone the walls, install new seals, etc).
I would clean up the area with brake clean and try to find the leak. It could be overfilled?
Are you using DOT 3 or DOT 4 brake fluid?
Yesterday i saw that the fluid was well below the full line and I had fluid on the garage floor. I started the engine a couple of time to burn off the fluid on the drivers exhaust.
Next, I filled the MC to the full line and drove the car. All is well. This morning I look under the car and notice a small spot of fluid, less than on ounce. My wife drives the car, the it sits all day.
I come home from work, check under the car and notice more fluid, 3-4 ounces I guess. I notice that the MC is above the full line.
When the key is turned on the brake system pumps fluid for about 6-8 seconds, maybe 10. The fluid drops below the full line about 1/8 to 1/4 inch.
All looks well again...would someone with an SC430 check to see if their car acts this way?
Please make sure the car has been sitting for 6-8 hours first. And you only need to look at the fluid level first, turn the key on, not engine, then get out to see how long the MC pump runs and how much fluid is pulled into the system.
DOT 3 and DOT 4 fluid. It is qualified as both. Valvoline.
Just looking at everything again and I just do not see how it is dripping on the drivers side cat. The cat is all wet. I will put it on ramps tomorrow.
Also, at this point I really do not believe the MC is the problem.
Bgw70
Just did what you requested on my 06, starting the fluid was above the fill line, turning on it pumped 3 times in about 12 seconds total to below the fill line, dropped about 1/2 to 5/8 of an inch total. Car had been setting for 2 days. Good luck, hope this helps.
Mike
Bgw70
Just did what you requested on my 06, starting the fluid was above the fill line, turning on it pumped 3 times in about 12 seconds total to below the fill line, dropped about 1/2 to 5/8 of an inch total. Car had been setting for 2 days. Good luck, hope this helps.
Mike
It sure did! It let me know that the system on my car was operating correctly! Thank you so much for the help!
Now I just need to figure out where the brake fluid is leaking from...
From my personal experience, same vintage Soarer 1991. Mine was filled with only DOT 3 and another with a DOT 4. Mine had more 120k km more km than the other Soarer. The Soarer running DOT 4 required new brake lines and the master cylinder seal was leaking. My Soarer were on original brake lines and seals.
The Soarer originally came with DOT 3, same with the SC430. Maybe over long period of time there is a difference in properties between DOT 3 and DOT4 which effects the rubbers and seals. Most people do not keep their cars for over 6 years so the problem doesn't occur until later down the road.
A DOT 4 fluid has a slightly higher boiling point BUT absorbs more moisture than DOT 3. Over long period of time moisture / water does not mix well with seals and brake lines. So people running DOT 4 fluid should be flushing the brakes more often.
From my personal experience, same vintage Soarer 1991. Mine was filled with only DOT 3 and another with a DOT 4. Mine had more 120k km more km than the other Soarer. The Soarer running DOT 4 required new brake lines and the master cylinder seal was leaking. My Soarer were on original brake lines and seals.
The Soarer originally came with DOT 3, same with the SC430. Maybe over long period of time there is a difference in properties between DOT 3 and DOT4 which effects the rubbers and seals. Most people do not keep their cars for over 6 years so the problem doesn't occur until later down the road.
A DOT 4 fluid has a slightly higher boiling point BUT absorbs more moisture than DOT 3. Over long period of time moisture / water does not mix well with seals and brake lines. So people running DOT 4 fluid should be flushing the brakes more often.
All great points and much appriciated! I too have read this somewhere before.
At this point, finding the source do the leak is my priority. I looked at everything again last night and it appear the fluid is dripping from the insulation to the cat. This would bring me back to the MC. If that is the case, I would guess that the seal on the MC piston would be the cause. The piston connects to the push rod and then the brake pedal.
Since these things are $1500-$2000, I may just purchase a rebuild kit and do the work myself. It has been a few years but the process looks straight forward.
Be extra careful with the nitrogen brake accumulator. Not sure if this needs to come out or not. I have a right hand drive SC430 its the black cylindical canister behind the brake reservoir.
Can you also put up the seals part numbers for future reference. Thanks.
There are a number of them on eBay (used). yes, they are pricey, and much more elaborate than I expected. Ranging from $500 and up. Also noticed that the usual on-line parts places (not Lexus specific) don't stock it. That says something right there.
The Master cylinder was removed tonight and it appears it is leaking on the bottom but I cannot locate the exact place.
Bottom view, note the fluid in the allenhead bolt hole.
Side view, we removed the black plastic cover and noticed fluid all over the lower right hand bolt (not shown) and in the hole where the one inch bolt goes into the MC.
Another side view. This is the side where three of the five electrical connections are made.<br/>Under the cover are some interesting sensors.
Another view of the bottom, to the right is the booster pump. The pump is not leaking, the area by the blue and red wires is wet with fluid. It is possible the MC is leaking between the two pieces of aluminum blocks. The area in the middle of the red loop, which is a brake line that connects the booster to the MC. A bolt can be seen in the lower left.
The master cylinder pressured up properly when the key was turned on, the brakes also felt good. I visually checked the unit for leaks, after it was pulled and saw none. The VSC lights were off.
02-25-15, 10:14 AM
SC430 Brake Fluid Leak
