Bleeding brakes?

[bertsm]

When I acquired my 1992 190e almost a month ago, the front pads where so warn that I had to push the pedal so hard to get it to stop. My mate fitted some new pads and immediately the braking improved. However when I start the car in the mornings for the first few hundrend meters the brakes feel like before and and as I drive further they start to work without me having to push the pedal so hard. Also the pedal travel is the same so I don't think its the master cylinder here, so I'm thinking may be the brakes need bleeding. Can some tell me how I go about bleeding them. Car has no ABS. Thx.

 

[BlackC55]

Sounds like you have a sticking caliper piston.

Remove the pads again and check they are free and the boots are intact.

 

[wireman]

Do as blackc55 says check for a sticky piston, if unattended this fault could fracture the disk under hard braking and the wheel may jam up solid.

If your brakes need bleeding the pedal will feel soggy, to bleed them you do the back first and then front left and then front right.
Get four new bleed nipples from the dealers.
Buy some nice new fluid in a sealed can.
Find an assistant.
Lift the cars rear and put it on stands with chocks at the front wheels.
Remove wheels, remove and replace with new the bleed nipples - quickly so that fluid does not escape all over.

Make sure the fluid reservoir is full.

Fit a suitable length of flexible tube to the nipple and put the open end into a jar to collect the old fluid,open the nipple about 1/2 a turn then the assitant can gently press the pedal to the floor and release it back to the rest position, the pedal must be returned fully up on each stroke.

Do it again and again untill any air bubbles that may be in the system are expelled.

Make sure the fluid reservoir is full. (assistants job)
Do the other rear wheel, as above.

Make sure the fluid reservoir is full.
Refit the rear wheels and lower the car to the floor.

Lift the front end as above,
Remove the LH wheel and proceed as above.

Make sure the fluid reservoir is full.
Remove the RH wheel and proceed as above.

Make sure the fluid reservoir is full up to max.
Replace the wheels and lower the car.

Press the pedal and ensure that there is someting like a brake pedal there before you move the car.
Start up and move the car,
Try the brakes immediatly the car rolls then you know that there are some brakes available.

Check that it stops from 20mph before you get very far.

If you know that the fluid is less than 2 years old it will be OK, if you cant tell or just dont know then you should change the fluid. MB recommend annual fluid changes, after winter.
To change the fluid just do the above untill you get clean fluid out of the bleed nipples.
Oh and make sure the fluid reservoir is full up to max.

To correct a sticky caliper piston will reqiure a replacement caliper assembly.
The front single piston caliper is mounted on sliding pins which if the culprit can be cleaned up to slide nicely.

If your disks look a bit worn put new ones on they are cheap enough and make a real improvement to the behavior of the brakes.

 

[bertsm]

Thx guys will try that this weekend.

 

[C240yaz]

Do as blackc55 says check for a sticky piston, if unattended this fault could fracture the disk under hard braking and the wheel may jam up solid.

If your brakes need bleeding the pedal will feel soggy, to bleed them you do the back first and then front left and then front right.
Get four new bleed nipples from the dealers.
Buy some nice new fluid in a sealed can.
Find an assistant.
Lift the cars rear and put it on stands with chocks at the front wheels.
Remove wheels, remove and replace with new the bleed nipples - quickly so that fluid does not escape all over.

Make sure the fluid reservoir is full.

Fit a suitable length of flexible tube to the nipple and put the open end into a jar to collect the old fluid,open the nipple about 1/2 a turn then the assitant can gently press the pedal to the floor and release it back to the rest position, the pedal must be returned fully up on each stroke.

Do it again and again untill any air bubbles that may be in the system are expelled.

Make sure the fluid reservoir is full. (assistants job)
Do the other rear wheel, as above.

Make sure the fluid reservoir is full.
Refit the rear wheels and lower the car to the floor.

Lift the front end as above,
Remove the LH wheel and proceed as above.

Make sure the fluid reservoir is full.
Remove the RH wheel and proceed as above.

Make sure the fluid reservoir is full up to max.
Replace the wheels and lower the car.

Press the pedal and ensure that there is someting like a brake pedal there before you move the car.
Start up and move the car,
Try the brakes immediatly the car rolls then you know that there are some brakes available.

Check that it stops from 20mph before you get very far.

If you know that the fluid is less than 2 years old it will be OK, if you cant tell or just dont know then you should change the fluid. MB recommend annual fluid changes, after winter.
To change the fluid just do the above untill you get clean fluid out of the bleed nipples.
Oh and make sure the fluid reservoir is full up to max.

To correct a sticky caliper piston will reqiure a replacement caliper assembly.
The front single piston caliper is mounted on sliding pins which if the culprit can be cleaned up to slide nicely.

If your disks look a bit worn put new ones on they are cheap enough and make a real improvement to the behavior of the brakes.

This is a good post and should be made sticky.