Correct Brake Fulid 1967 mercedes 250S

[aluminum]

Hi 1967 Mercedes 250 S sedan

Is Dot 4 the correct Brake Fluid for a 67 250 S sedan .


what happens if you use Dot 3 rather than Dot 4 ?


Can ? using Dot 3 Fluid cause pressure and Caliper Problems ?



I picked up a 67 250s sedan that had been sitting not sure how long with Brake Issues . Replaced most everything including the pressure regulator for the rear wheels. as I was having pressure build up and Caliper sticking issues .



I read the Boiling point of the Fluid is different . Could Dot 3 Fluid perhaps Boil in a 67 MB sedan and cause issues and if so what sort of issues ?


Thanks for any Brake expert advice in advance fluid related

[Mike D]

Originally, 40+ years ago, your car had DOT3. Now? Although it is not inconceivable you still have only DOT3, depending on the maintenance of the vehicle, it probably has a blend of DOT3 and DOT4.

Either of the two is perfectly adequate for the task and CAN be mixed although this is not the optimal recommendation.

To be sure, do a complete flush and replace with the fluid of your choice.

More than you ever wanted to know about brake fluid:

https://www.lubricants.total.com/help-support?keys=&field_topics_tid=18

[rumb]

Dot 4 is fine, MB recommends changing brake fluid every 2 years. Dot 4 has a higher boiling point, so it is better.
If your calipers are slow to release you probably need new rubber brake hoses - they swell up internally and wont release the pressure.

[aluminum]

Originally Posted by rumb

Dot 4 is fine, MB recommends changing brake fluid every 2 years. Dot 4 has a higher boiling point, so it is better.
If your calipers are slow to release you probably need new rubber brake hoses - they swell up internally and wont release the pressure.

Thanks for reply Yes I read about the higher Boiling point humm

About that disadvantage ? so what happens if the fluid Boils ?

What sort of situation develops I wonder ? .



I did find previously a bad Brake line just as you mentioned .
I replaced them with ones I tested with compressed Air blowing through at about 90 Lbs and got a easy full blast stream of air to test them. Passing my test .



I found Receipts in glove compartment for brand new front calipers for over $800 however I noted they where painted with aluminum Paint ?

replaced some 1.5 yeas ago only

I have never seen New Calipers painted with such paint . I discovered them to be Very hard to pry open the Cylinders to pump out he fluid trying to loosen them up . The did loosen up and then worked much better but only for a day or so . So Then I replaced them with another set from another 67 250 SE Parts car I had .
Both these car where Very cheap to buy like $500 for1 and the other for free in fact but then you pour in $ or course

but the fun is worth it

thanks all for the help

What I suspected was that some shop had not replaced the Calipers at all but rather rebuilt them and the pistons where just not right most likley worn out ,then they painted them with aluminum paint and a huge bill.
The parts Car Parts I noted

I noted those calipers where easy to move the cylinders about and pumped them dry . As well I changed the rear calipers also pumping them dry



The entire 1967 250 s Braking system seems to perhaps be a doctored up system possibly I hope I am wrong .


To have a pressure Regulator for the rear Brakes because the rear Brakes tend to skid upon hard braking Thus lowering the pressure to avoid that seems like poor engineering possibly . ( Just my Opinion )



To have no adjustment for the Master Cylinder push rod under the hood

coming from the brake booster where it is easiest to get to points to the same poor engineering .To have a Adjustment under the Dash on the other side of the brake Booster rod to peddle in a Hard place to get to with a off center Eccentric bolt ? well this is very strange .
( why not have simply a adjustment right at the master cylinder like all other cars ? ) The system does work but make you work as well to make it work .

the rear brake pressure could be controlled in other ways rather then have a pressure regulator that must be replaced if bad rather then repaired .


I do find the 67 braking system to be a finicky system but perhaps I am missing something still learning the 67 system and its not simple at all .


anyone can make mistakes like me for example lol


On the other hand the car drives handles great . it certainly draws a lot of public interest for some reason and i tell people its my time capsule .


The gold one (67 s )is a 4 speed manual column shift

the white (68 S) a auto trans