I figured out what was going on with my car's brakes. RR caliper was dragging, heating up, and possibly sucking air or boiling fluid locally. Replaced it, bled the system.

Had an oh-^%&# moment as I realized the cap said DOT-4, and I had just poured in DOT-3 (boiling point 450) fluid. From what I understand, those are chemically compatible, so it's unlikely to eat my system from the inside out. Should I just re-bleed all four wheels this weekend and call it a day, or is there a risk of doing damage?

I'd just remember to use DOT4 next year. New DOT3 has a higher boiling point than 2 year old DOT4. They are completely compatible, I wouldn't re-bleed right now.

Did you bleed all 4 corners when you did the repairs?

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

It will be fine, nothing to see here. It's a 240D right? Hard to imagine a car that needs DOT4 less. I bet you could use DOT2 and it would be ok!

I don't think you need to worry about boiling brake fluid in a 240D unless you have a dragging caliper.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

It won't fail you ala physics.
Usually each step up in DOT is better.......old lower grade DOT was heavy alcohol/vegetable based and alcohol absorbs water real good causing system corrosion.

Perhaps this supposed "brain fart" is a confusion with silicone brake fluid?

DOT 5 silicone brake fluid warning

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

No: didn't use silicone fluid, just regular glycol based dot-3

Some of the companies are now blending DOT3+DOT4 and selling it by the quart.

NAPA may be one, not sure.

__________________
Strelnik
Invest in America: Buy a Congressman!

1950 170SD
1951 Citroen 11BN
1953 Citroen 11BNF limo
1953 220a project
1959 180D
1960 190D
1960 Borgward Isabella TS 2dr
1983 240D daily driver
1983 380SL
1990 350SDL daily driver alt
3 x Citroen DS21M, down from 5
3 x Citroen 2CV, down from 6

I can't imagine a 240D calling for DOT4. Should not be an issue anyway.

__________________
Jim

If you have a dragging caliper, the brake fluid is not the cause. If it were, they would all be sticking. Sounds like time for rebuilt calipers. Regularly changing BF can postpone the onset of caliper problems.

__________________
'83 300D, 126K miles.

^as rscurtis said.

__________________
Jim