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#1
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W126 brakes
Ive been driving around the SD a little more often as i got the old tug boat running better again. Ive noticed that my brakes are very loose or marshmellowy. I have to stomp down on the brakes for it to brake propely. My guess is the caliper's need replacing but the brake fluid looks kinda brown. Last i remember i didnt change the brake pad sensor's so that could be a possibility as well.
Checked the pads and they still look new, no squeals. The rotor is new as well. Tell me what you experts think.
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Current: 05 E320 CDI 07 GL320 CDI 08 Sprinter 05 Dodge Cummins 01 Dodge Cummins Previous 2004 E55 AMG 2002 C32 AMG (#2) 1995 E300 1978 300D 1987 300D 2002 C32 AMG(blown motor :[ 1981 300SD 1983 300SD 1987 300SDL 2002 Jetta TDI 1996 S420 1995 S500 1993 190E 2.6 1992 190E 2.3 1985 190E 2.3 5-Speed |
#2
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Fluid needs to be clear... not brown. Flush it and you'd be suprised how it'll stop.
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I'm not a doctor, but I'll have a look. '85 300SD 245k '87 300SDL 251k '90 300SEL 326k Six others from BMW, GM, and Ford. Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG] |
#3
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If your brake system is in similar condition as my 300D, then the brake fluid flush will help, but not completely fix the problem. I didn't get rid of the kinda mushy pedal till I replaced the master cylinder. Braking feel and stopping distances improved substantially. Basically the brakes got a lot more responsive (sensitive if you will) after I changed the MC, and I found I could stop the car with a lot less pedal.
Damn thing was leaking into the brake booster. I need a new booster but dont want to pay for the crazy pennies they go for. Anyone know where I can score a rebuilt one?
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1985 CA 300D Turbo , 213K mi |
#4
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Hmm, I've got three parts cars, I may be persuaded to give up a booster. PM me.
John
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!! 1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere! |
#5
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My SD has always had a "softer" pedal than our '83...with the '83 it comes on a little, then press harder and it stops HARD, extreme power there. Mine is steady....then press harder = more braking, press it quick and hard and it will smoke the tires (found that out on the freeway a couple months ago when avoiding an accident! ) Both car's brakes have felt the same since purchased, no degrading in performance. They must just each have their own personality. I prefer how my brakes feel....to those on the '83
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-diesel is not just a fuel, its a way of life- '15 GLK250 Bluetec 118k - mine - (OC-123,800) '17 Metris(VITO!) - 37k - wifes (OC-41k) '09 Sprinter 3500 Winnebago View - 62k (OC - 67k) '13 ML350 Bluetec - 95k - dad's (OC-98k) '01 SL500 - 103k(km) - dad's (OC-110,000km) '16 E400 4matic Sedan - 148k - Brothers (OC-155k) |
#6
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Ok ill change out the fluid as a start. What fluid is best? at my work we have many different brands of fluid and difference "performance" levels of fluid. Its all DOT4 though.
From ATE we have one designed for ABS systems, ATE gold, and ATE super blue racing fluid. From pentosin its just called supersin DOT4.
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Current: 05 E320 CDI 07 GL320 CDI 08 Sprinter 05 Dodge Cummins 01 Dodge Cummins Previous 2004 E55 AMG 2002 C32 AMG (#2) 1995 E300 1978 300D 1987 300D 2002 C32 AMG(blown motor :[ 1981 300SD 1983 300SD 1987 300SDL 2002 Jetta TDI 1996 S420 1995 S500 1993 190E 2.6 1992 190E 2.3 1985 190E 2.3 5-Speed |
#7
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I was told to use synthetic 5.1 closest thing I could find is valvoline synthetic "better than dot 4" no rating on it... odd.
it is real good fluid though. and once I flushed out and changed the calipers on my 79 TD it stops on a dime and gives change. John
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!! 1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere! |
#8
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Dot 3 and 4 are interchangeable... I think dot 4 has a higher boiling point then dot 3. Dot 5 is silicone based and will not mix with dot 3 or 4. So leave that alone.
My knee jerk reaction is the change the fluid. 9 times outta 10 that is your problem. If you really think it’s your master cylinder get a master cylinder test kit from the parts store. It will just be a box with a bunch of different brass plugs in it. Remove the break lines from the master cylinder and put the plugs in the master cylinder. Then press on the breaks. If the pedal sinks you have a master cylinder problem. Don’t go to the work of changing the part without this test. Why fix what an't broke.
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1983 Toyota Tercel 4WD Wagon - 1984 Mercedes-Benz 300SD 4-Speed(My Car!) 2005 C230 Kompressor 6-Speed Manual
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#9
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You can just pull inspect the MC yourself, no need for a test kit. If you look at the plunger theres a nice thick rubber o-ring around it. I could see that brake fluid was slowly getting through this seal.
I say replace it now before it fails, if it hasn't started to fail already. What is the lifespan of rubber? My dad said "Ahhh the brakes are fine, don't fix it, it isn't broken," too. After I replaced the MC i took him out for a drive and gave him a little whiplash from the brakes (haha nothing serious) and he conceded that it "may" have needed replacement. I was surprised as well, I could never get the brakes to lock up before. They almost felt as good as our old 300SDL's brakes, which really kicked ass. Bit hard. Get em now before they get more expensive. 100 bucks is pennies considering the improvement it makes.
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1985 CA 300D Turbo , 213K mi |
#10
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The only reason to buy the test kit is because there is no need to remove the MC from the car. You can feel a leaky seal with you foot when you aren’t pushing fluid thought the lines. It’s like 15 bucks and it comes with all the plugs you need for most every car. I see it as an investment in a tool, and every man likes tool shopping.
you can diagnose all break problems simply by starting at the MC and plugging the lines. start by plugging the MC if there is a leak you will fee the pedal move. There is no where for the fluid to go if the outlets are pluged. So if the seals are good the fluid won't move, thus the pedal won't move. If that is solid, move away from the MC remove the live from the caliper and use the test kit to plug the line. See if there is a leak in that lag of the system. If no leak move on. Leaks are normally easy to spot because of drop on the ground. But some time it’s more trick then that, like a warn break line where the rubber is bulging. If you have all the lines plugged that the bottom theory says that no fluid can't move so no pedal movement... but if a line is bulging, the pedal will move, and you'll be able to track down the problem. It’s all common since, you just have to look at how the hydraulic system is designed and then start trouble shooting. Changing your break fluid is probably the problem, because break fluid contains no water, but it likes to bond with water, so the older the break fluid the more water it will have pulled out of the air, which causes the steel parts to rust and that darkens up the break fluid. And as with any fluid heaver stuff sinks to the bottom, in this case the calipers. And we all know what small chunks of crap do to machined surfaces, causes scores and that causes leaks. So old break fluid can cause rust and rust chunks can eat up calipers. Changing you break fluid is important, in dry placed like Arizona the fluid may get 10 years before it is polluted with water. But in wet places like Germany the break fluid is changed yearly if not more. Check your service manual, they won’t tell you about the water, but they will get you an interval to change you fluid. And I bet it’s going to be more often then your Chevy.
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1983 Toyota Tercel 4WD Wagon - 1984 Mercedes-Benz 300SD 4-Speed(My Car!) 2005 C230 Kompressor 6-Speed Manual
Last edited by SirNik84; 11-10-2006 at 04:23 AM. |
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