adding brake fluid?
 

The red BRAKE light flickers a lot,but not predictably or in any pattern.I'm guessing I need to add brake fluid.Is this advisable?That is,can one just "add" fluid if it is "low", or do you have to bleed and flush,etc.? I've a '82 240D. What fluid is recommended?I'm a novice here and any advice is appreciated!! Dave in Boston

If your brake pedal pressure isn't spongy, try removing the brake fluid reservoir cap and add some fluid. I'm not certain about what to use in a 240, but I'd bet Dot-3 would be fine. If the pedal is spongy, I'd take it to a shop fast. The weather in your area is not very forgiving to faulty brakes.

This isn't something you want to delay for very long. Have a tech determine the cause of this problem.

If you only see it flicker when you step on the brakes, it may be the sensors telling you the fron pads are near end. If it's spongey, that's another matter. Also, the book officially calls for dot4 fluid.

MB recommends Dot 4+ in all of their cars. Don't mix fluids & never use fluid that the container has been open(ed) for more than a year. Even with the lid on.
IF the brake warning lamp comes on, the pads should be checked & if they are OK then possibly you have a leak.

There's a difference between the red BRAKE light and the yellow round light that indicates front brake pad wear.

One of the things that can trigger the red BRAKE light is low fluid in the reservoir. That's the first and least expensive thing to check first. If it is low and you add some fluid, keep an eye on it to make sure its not going down again. The reservoir level does go down slowly as all the brake pads wear - you just want to make sure the fluid level is not going down fast as in a leak situation.

Ken300D

Does the 240 have a hand brake? I ask because I don't know.

What I do know is on the 108 I had a flickering brake light. Only thing I could find was the parking brake cable needed adjusting. I could make the light go out by pushing the hand brake handle toward the dash. When the cable gets slack the spring will keep the handle from engaging the switch.

Check it out.

Both my brake lights are RED. The only orange lights I have are the radiator annd the Oil level light on a 1987 190

The brake light serves 2 purposes. One is to tell you the brake is set and the other is that the brake fluid is low. Your brake reservoir is clear (opaque) and you should be able to see the fluid level. If your fluid is real dark the it needs to be changed, but that's another subject. If your fluid is low, lust add some. Be VERY careful not to spill any. Brake fluid is very corrosive, especially on paint. Use DOT 4 brake fluid only. DOT 4 can handle higher temps than DOT 3. DOT 4 can be bought at any Walmart. I have actually gone to 2 different auto parts stores and they didn't have DOT 4.

There is never any reason to add brake fluid to the reservoir. Brake fluid may be deliquescent ( takes moisture from the air),buy it doesn't evaporate. The reservoir is large enough to accomodate all 8 brake pads to wear to the minimum. When you push the caliper pistons back, the fluid level rises back to normal in the reservoir. When the red brake light flashes or comes on solid, you have one of two conditions. Your pads are worn down or you have developed a brake fluid leak. If you do develop a serious leak, don't panic, because modern cars have two isolated circuits. Brake efficiency will be reduced, but you will always have brakes at two wheels to get you to the shop safely as long as you realize that you are driving with defective brakes. To recap, there is no reason to top off brake fluid. When the red light starts flashing or comes on there is a reason and you should have the brakes checked.

Peter

True, in a perfect world, the brake fluid would never need to be topped off. But here's a scenario where it might need to be done (and a likely scenario I might add):
Front pads wear down to minimum -- rears are fine. Front pads are changed, piston's retracted with fluid allowed to bleed out at the caliper -- so now there's less fluid in the sytem. Granted, the reservoir SHOULD be topped off at this time. But if it wasn't, then as the new pads continue to wear, the fluid level drops to below spec., and the warning light comes on. Add fluid, and the problem is solved.

Obviously the fluid should be checked when the brakes are serviced. And I agree that if you get the light, it's a good idea to inspect the entire braking system. But when you're looking over the system, don't ignore the obvious.

Just my 2-cents -- arguably worth that.

TVPIERCE,

You've added a fly to the ointment by opening the system and of course when you bleed brakes you would top off also. I also go along with the idea of letting some of the old fluid out instead of forcing it back into the system. I was merely pointing that in a closed system the brake fluid should never need topping off unless you have lost some while working on the brakes.

Peter

You can even top it off
 

The CD ROM Manual says that (after bleeding the system) if the customer complaines of a spongy feel to top off the reservior. I didn't think the reservoir held pressure, but it is right in the manual.

brake fluid flush
 

i believe that MB recommends flushing/relacing brake fluid every 24 months. do i think it is necessary: no. do i think its a great idea: YES!!!

if your fluid is older than 2 years, i would recommend having the system flushed and filled with fresh to spec fluid. cheap insurance that could avoid a BIG headache.

i know i could push my car if necessary, but id hate to TRY to stop it flintstone style! :eek:

its also a good time to have the entire braking system inspected.

Actually for the year of her car and mine, 1983, MB was still saying to change the fluid every year, in the Spring time if possible.