Hi all, you have been helpful in the past.
I have a problem, and don't know what to do.
Last week I rebuilt my left front caliper.

I didn't bleed all the way and found my brakes not working.

I had my 80 240d towed to my beloved mechanic, to have the brakes properly bled.
He broke off the bleeder nut on the caliper I rebuilt.

He eventually got the brakes to work enough to get home, and to the auto store to buy a new caliper.

We found a piston on the caliper I rebuilt was too shot even for the rebuild, so I bought a new caliper, I get it today.
He wants the car back Monday to bleed the system and install the new caliper.

I wonder if I should just install the caliper and bleed myself after he bungled the attempt before.

First off: do I/we turn the bleed nut on the caliper clockwise to open?
He turned it the regular (counterclockwise) way and perhaps it was just rusted on but I wonder if he didn't turn it the correct way.

Also, if I install the caliper, do I just need to bleed the one brake or do them all again.
The only one he couldn't bleed was the one he broke the bleed nut off of, that's how I have some braking power.

I have to pump the brakes twice to get an stopping power right now.

I'd hate to spend even more cash if I could do the work myself.
I have a mityvac, or could do it the two person way.

The only instruction pdf's I have list steps, but they are general, and don't have info like where is the bleeder nut on the master cyl, which way you turn it, for how long etc.

Thanks for any advice.


.

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1980 240D 260k miles , the last car I will ever buy

he turned it the correct way.
since it's broken off in the closed position, (we hope!) he broke it, closing it.
if the pedal is going to the floor, either you are out of fluid, because of a leak, or your master cylinder is/has failing/failed.
check your fluid level, if it's full DO NOT DRIVE THE CAR!
get or build a power bleeder, motive sells them here on our parts site. just type in your vehicle description, and choose brakes, and it'll be at the bottom of the list.
or you can build one from a BRAND NEW PRESSURE SPRAYER. do not use a used one.

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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
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A couple of things.

A caliper isn't considered "completely rebuilt" unless the bleeder screw was freed up. It is very doubtful that he turned it the wrong way as this is a very basic operation. If he was told the caliper was rebuilt, he would be expecting the bleeder screw to be free.

The trend in your post is that " . . .He broke the bleeder off. . ." . Please don't blame the mechanic, bleeder screws get stuck and rusted all the time. This situation is a prime example why , back in the day, I would not work on cars that the owner had performed home repairs.

One caliper can be bleed if the other three were prior. A couple of one person brake bleeding tips.

Put a 1 ft piece of vacuum hose over the bleeder screw and direct it towards a pan. Open the screw 1/2 turn, if fluid does not start dripping out after 2 minutes, press and release the brake peddle a inch until fluid comes out. Let the fluid drip for a few minutes while making sure the master cyl does not run below 1/2 inch of fluid left. Clese the bleeder when you stop seeing bubbles.

If the peddle is still soft, open the bleder screw and compress one caliper piston at a time, this will expel and air left in the piston bore.

Another way to one person bleed is to open the bleeder screw ever so slightly then push the brake peddle with your foot. A very slow stream of fluid ( and air ) will come out but when you release the peddle the near closed screw acts as a check valve.

It's easy to break a rusty bleeder if you're not careful, patient or lucky, I've broken a couple. Heat, patience and penetrating lube help. Nasty bleeders, if removed can be replaced w/ new for about ten bucks. You may get the old one out w/ a left hand drill or easy out. Small easy outs tend to break, but you're really trying to save a $100 caliper, right?

The master cylinder has 2 pistons, each powering brakes on opposite corners of the car (LF, RR and RF, LR). If air is introduced into the MC, you at least need to bleed brakes at both wheels served by that piston.

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CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

Not so. The pairing is "front" and "rear."

To do a five-minute job?

For the 240 D in question ,as with most rear drive cars, they are paired 1 set front and 1 set back.

However, 80's Volvos use a triangular split where each front caliper has 4 pistons and 2 hoses. Each front caliper has 2 circuits, one left is paired with a right and one rear caliper. The intent was that if one circuit had a leak, you would still have substantial braking force on 1/2 of both front calipers and only one rear. Losing one rear caliper isn't a big deal and will only cause a slight pull.

Front drive cars do typically have a diagonal split. This is done because , due to high front weight bias, the front brakes do most of the work. Stopping a front drive car with rears alone is very difficult. We can get away with the diagonal split because front drive cars have high negative scrub radius to counteract driving torque.

In other words, if the right front is the only brake working, the car will want to rotate ( yaw ) about that wheel to the right. With negative scrub radius, the wheel under braking imparts a steering force to the left. The two forces more or less balance each other out keeping the car straight. ( The diagonal rear brake helps things too. )

Fascinating. I always thought the brake systems were just split front/rear. Want to know what's worse? I have an ASE cert in brakes.

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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 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

In the context of front braking and rear braking =>

May I add that if there is too much braking force on the rear wheels you end up with an unstable braking situation - hooligans might think you are performing a wicked hand brake turn...

...that's why the pistons in the rear caliper are of a smaller diameter than the front ones. (Force = pressure multiplied by area => bigger area; bigger force for the same applied pressure)

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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!

forget the mity-vac. get a motive. pressure bleeding always yields better results than vacuum. at least in my experience. motive gets the air out and makes bleeding an easy one-man job.

I have an 82 Volvo Diesel and bleeding it is different enough I keep a copy of the Bleeding instructions in the Glove Compartment.

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84 300D, 82 Volvo 244Gl Diesel

The problem with the Vacuum Method is that when you back off the Bleeder Screw it creates a little Vacuum leak. You need to keep pumping with the Mighty Vac type Tool. However, it does work.

I have also had good luck with simply applying a little Vacuum; leaving the Hose on the Bleeder Screw but disconnecting the Mighty Vac and simply walking a way for a while and letting Gravity take care of the Bleeding (the Brake reservoir Cap needs to be removed to do that).

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84 300D, 82 Volvo 244Gl Diesel

So…the rear end wants to stop and the front end keeps going. What's unstable about that?

Is using the emergency brake unstable?

When the rear has excessive braking force, it locks the wheels. A sliding tire has less traction than a properly braked one, so the rear end tries to pass the front.
I'm still trying to figure out how you rebuilt the caliper, then found out after the fact that the piston was too worn for a rebuild-

i don't think unstable is the right word, but yes, brake bias will be out of whack. maintaining correct brake bias is important so that one end does not lock up before the other during heavy braking.

Not to pile on but, I'd still trying to figure out how the mechanic is being blamed for twisting off a bleeder screw on a " rebuilt " caliper by unscrewing it.