W115 Caliper Problems Please Help!!
 

Alright guys, I need your help. I took the front driver's side caliper off my 76' 300D to do some routine cleaning, when I put it back on and bled the brakes, the brake light came on and never went back off. I believe I have found the problem to be the caliper is leaking brake fluid. Ok, hear is what I know, the caliper is a dual piston Ate 64Rm. The caliper comes off in two pieces, There are two very small seals inside the caliper where the two pieces join together, these are leaking. So far I can't find the seals anywhere, Auto Zone, Napa, and yes Mercedes. Has anyone else had this problem? Can anyone give me some advice? Any help would shure be appreciated! I also know that I can buy a whole new caliper from Auto Zone for $59.00.
Thank You

whoaaah
 

partner. you are making it too difficult. the calipers should not be split unless leaking. they come off as a unit. personally i wouldnt remove a caliper to clean anything unless i needed to change a rotor or actually replace or rebuild the caliper. kits for the o rings you need are available for cheap. or you can use the rebuilt units you mention although i cant speak for them.

tom w

Did you separate the two halves of the caliper? If it is an ATE, you're really not supposed to. Even when replacing the piston seals, you don't need to separate the halves.
If that is indeed what you did, you probably wont find those seals anywhere.

Thanks
 

Thanks guys, indeed I did split the two halves open.Tom you said I could get the o-ring set, where could I find it? You guys can believe me this will be the last time I ever take the caliper off in two parts.
Scott

i assume
 

that such parts are available from the usual sources of mb parts. brian carlton has split them i think. maybe try pm to him

tom w

Good luck with the seals. If you do find them, you might need to check with ATE about the torque specs for the halves. In the manual, it says not to separate the halves because they are torqued unequally at the factory.

well
 

that sounds like you will have to buy the rebuilt calipers. i must be wrong about brian splitting them. now that i think more i believe he must have changed the puck seals and dust shields only.

tom w

Thanks guys
 

Thank you guys for all the help, I will just order the caliper, now I'm just fighting trying to get the caliper bolts out. lol

Ok....
 

Alright guys, I put the new caliper on, I have bled the brakes like crazy, used a quart of brake fluid, and not only can I not get the brake light to go off, but the brakes are extremly spongy and weak! I have cracked open and bled every line I can find including the ones coming from the resevior and the master cylinder. What is the deal, has any one else had this much trouble over a caliper? Any help would be much appreciated!!

Sounds like a bad master cyl. or you could still have alot of air in the system.

Try gravity bleeding the whol system. crack all four bleeder screws and let gravity do the work. make sure you keep an eye on the fluid level.

The brake light comes on when the fluid level is low in the master cyl.

If your master cyl was weak, bleeding the brakes may have wiped it out. I would pull the master cyl and check if it is leaking into the booster.

Good luck

whoooah
 

there... i am thinking you are not bleeding the brakes correctly. here is how. make sure the mc res is full. go to the pass rear and start bleeding there. this is a two man job or person. have the person in the car pump the brakes til the pedal feels hard and hold the pedal down. you open the bleeder and allow it to flow fluid out till it stops bubbling or til the pedal reaches the floor. hold it down and close the bleeder. pump it up again til it gets hard. repeat til you get no bubbles at that caliper and move to the driv rear and repeat. then pass front and then drivers front. put a tube on the bleeder and run the old fluid into a jar. now if you do all this and still have a problem, you need to look at the mc. i am betting this will cure the prob.

others advocate using a mitivac, but personally i have never been able to get those to work for brakes.

tom w

Sounds like you have a faulty master cylinder...

Had a similiar experience with my beater [87 Corolla]... had replaced a faulty/leaking caliper and was bleeding the system after that [caliper replacement] task.... car simply would not bleed...

[New] fault was faulty master cylinder >> [note: a master cylinder does not have to leak externally tobe failty] >> the internal piston seal can leak > which prevents adequate pressure to be developed ...

my .02

Thanks guys, I put a new master cylinder on, I am still having problems gettign all the air out of the lines it is a very time consuming project, and yes I did bench bleed the master cylinder.

did you follow
 

my recipe for bleeding?

if not done that way it wont work.

unless you followed another correct method.

tom w

Without being there to see what you are doing, it is hard to advise from a computer terminal. Some of your problems might come from your parts source. I would never buy or suggest anyone buy that junk from Auozone, Napa or any of the others. The out of the box failure rate is extremely high on that junk. After you've busted your ass for hours the counterman in tha air conditioned store smiles as he hands you another one under warrantee. Do the math, man. You pay $85.00 for a part that has been marked up by a retailer, a jobber, a wholesaler, a distributor, and a rebuilder. That is 5 markups. How much time and material do you think that rebuilder can afford to put into that product? I just saw this the other day at a shop in my area. The owner got a master cylinder from Napa. The first one leaked, the second one wouldn't bleed, and finally the third one worked. About a year ago a friend needed a starter in his turbo diesel. His wife works in the warehouse for Kragen so she got th starter for about $105.00. I went to his place and smcked his old starter with a hammer so the car wouldn't need to be towed to my shop. I installed the Kragen starter, and he called me a week later saying the wasn't starting again and he thought he needed a battery. I told him that he needed a starter. I installed a bosch rebuilt starter which was consideably more expensive, but he hasn't had a problem since. Sine he's a good friend, I didn't charge him for my time. I'm sure others will disagree with me, but I value my time.


Peter