Addin Brake Fluid, Cannot see the Amount..

[lindajane]

Hello,
I think I may need some brake fluid, according to my mechanic.
Trouble is, the container that is so old and cloudy, I cannot
see through the exterior to see how much brake fluid is already in
there, and it seem to be a bit tilted. Is there another way to check?
I want it to the Maximum line right?...I have an 1983 300D...
Thanks
Linda

[Junkman]

Make a dip stick out of something and guestimate it or replace the reservoir.
Just a FYI, changing brake fluid periodically keeps the gunk out of your calipers and helps them live longer. Brake fluid absorbs water and flushing gets rid of the water.

[vstech]

Just fill it to the brim of the container... suck out all old fluid you can first... then suck out a little to get it well below the rim.

[vstech]

It is tilted so the front and rear reservoirs get fluid even if one side is leaking, or worn low.

[lindajane]

Thanks..
So it's better to try and remove the old brake fluid before adding
more?...is there a chance of putting in too much,
and my mechanic said it was ok to use number 3 or 4 brake fluid,
since I have an older car...do you agree with that?
Thanks

[SonnyMorrow]

If you remove the lid, you can peer into the reservoir and check the fluid level. I have had the same issue. The reservoir container is supposed to be transparent, but age has taken its toll.

[Maxbumpo]

Don't worry about too much brake fluid, that is an inconvenience. Too little is a bad problem, potentially life threatening.

Put some rags around and under the reservoir while filling to contain any spills, brake fluid will attack the paint and later lead to rust if not cleaned up. If you do spill some below the reservoir and can't get it all cleaned up with a rag, just flush it out with water. There should be a drain under the reservoir area, so water will exit at the back of the fender well area, or next to the transmission. Leaves and dirt may have collected, this would be a good time to clean all that out if possible.

The brake fluid reservoir has two internal compartments, one for the front brakes and one for the rear, and the rear compartment won't start to get any fluid until the front compartment is completely full and it looks like fluid may start overflowing out of the top.

Your car may have a plastic strainer / filter thing inside the reservoir, it is just sitting there, so it can be pulled out with your fingers so that you can see inside better.

[vwnate1]

All of the above plus : a cheap syringe from the Dollar or Drug Store will easily suck out some old fluid .

Yes, use DOT 4 if you can find it, DOT 3 if not .

Consider having the brakes flushed and bled if the current fluid is black ~ as mentioned brake fluid is hygroscopic, this means it draws water right out of the air, why it turns black over time .

You're supposed to flush any hydraulic brake system every two years but no one ever does .

Those few who do rarely ever need to replace the various cylinders .

[chronometers]

Mercedes specifies 2-year brake fluid change intervals. In moist climates or those that see great temp fluctuations, this is even more important.

For the SBC equipped cars, this is perhaps even more critical.

Don't wait for the fluid to become black!

[BillGrissom]

Agree, you should flush. But that requires opening the drain at each wheel caliper, and not letting it run dry. For a quickie, at least suck all the old fluid out of the reservoir that you can first. Don't actuate the brake pedal while empty so you don't get air into the system. Fill with fresh fluid from an unopened bottle. Ditto on "clean up spills". I save old glycol brake fluid to use as a cheap paint remover. Also, change the rubber "test caps" at top of reservoir if old and cracked (cheap here at P-P). That a great place to let moisture into the reservoir.

Best to worst is DOT 5.1, 4, 3 (all glycol). Even better is DOT 5 (silicone, I use) since it doesn't absorb moisture, but a bit of a specialty. Don't pay extra for "synthetic". All brake fluids are synthetic and have always been, unless someone can point to a mineral-based fluid (i.e. oil).