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Thread: ABS Brake Master Cylinder Assembly - Teves Mark II - (1989 - 1992)

  1. #16
    Join Date
    May 2012
    Location
    Lodz, Poland
    Posts
    27
    New facts:
    1. Pump runs after turning ignition switch on, but only for a while. It doesn't give pressure.
    2. As I have mentioned there are no red or amber light (bulbs are not burnt for sure - we checked it carefully)
    3. When we have applied power directly to the one of pins (in pressure warning switch - 5 pin plug), pump started working and giving pressure)
    4. Pump is washed and right now we are observing where is the leak

    Electrician said that ABS fuse and ignition switch are rather OK. (I have changed my ignition switch 3 years ago for the new one)

    Now I really don't know what to do...


    Quote Originally Posted by the-big-e View Post
    I'm with Dave on the ignition switch.....

    But you really need to find out where the brake fluid id coming from.....

    Most likely the front seal of the pump motor or the rubber supply line from the reservoir to the pump....

  2. #17
    Join Date
    Oct 2004
    Location
    Charlotte, NC
    Posts
    8,159
    Sounds like a pressure switch problem.....

    When there is no brake fluid pressure to the switch, the pump will run.....

    Once the proper pressure is achieved, the pressure switch breaks ground to the pump motor.....

    Now you have to find the leak....

  3. #18
    Join Date
    Jul 2003
    Location
    Eastern (nee Western) PA
    Posts
    4,988
    If the soft hose leaks, you can get a replacement from Contitech. It is the same type of hose used on 84-91 BMW 3-series cars. I mention this because you may find that easiest to get in Europe.
    God bless!!!

    1990 SC auto ... red outside, gray cloth inside ... ~205,000 miles (and climbing) ... driven daily!

  4. #19
    Join Date
    May 2012
    Location
    Lodz, Poland
    Posts
    27
    Is it possible to replace this pressure switch? Do you have one for sale?

    Quote Originally Posted by the-big-e View Post
    Sounds like a pressure switch problem.....

    When there is no brake fluid pressure to the switch, the pump will run.....

    Once the proper pressure is achieved, the pressure switch breaks ground to the pump motor.....

    Now you have to find the leak....

  5. #20
    Join Date
    May 2012
    Location
    Lodz, Poland
    Posts
    27
    Was it universal for all engine types in 3 series?
    Quote Originally Posted by S_Mazza View Post
    If the soft hose leaks, you can get a replacement from Contitech. It is the same type of hose used on 84-91 BMW 3-series cars. I mention this because you may find that easiest to get in Europe.

  6. #21
    Join Date
    Jul 2003
    Location
    Eastern (nee Western) PA
    Posts
    4,988
    Quote Originally Posted by Mike Brendzel View Post
    Was it universal for all engine types in 3 series?
    As far as I know, but I am not familiar with diesel 3-series.

    I am pretty sure that this is the part I ordered. (At the bottom of the linked page.) It fit perfectly.

    http://www.pelicanparts.com/bmw/cata...BRKhyd_pg3.htm
    God bless!!!

    1990 SC auto ... red outside, gray cloth inside ... ~205,000 miles (and climbing) ... driven daily!

  7. #22
    Join Date
    Oct 2004
    Location
    Charlotte, NC
    Posts
    8,159
    Quote Originally Posted by Mike Brendzel View Post
    Is it possible to replace this pressure switch? Do you have one for sale?
    Yes, I just got one off a unit I took out a few weeks ago...

    Give me a zip code to ship to and I'll quote you a price that includes shipping.....

  8. #23
    Join Date
    May 2012
    Location
    Lodz, Poland
    Posts
    27
    Private message sent


    Quote Originally Posted by the-big-e View Post
    Yes, I just got one off a unit I took out a few weeks ago...

    Give me a zip code to ship to and I'll quote you a price that includes shipping.....

  9. #24
    Join Date
    May 2012
    Location
    Lodz, Poland
    Posts
    27
    Thanks for the hint. I am thinking of buying a whole set of seals and hoses for brake assembly. Does anyone sell these kits or I have to complete it by myself?

    Quote Originally Posted by S_Mazza View Post
    As far as I know, but I am not familiar with diesel 3-series.

    I am pretty sure that this is the part I ordered. (At the bottom of the linked page.) It fit perfectly.

    http://www.pelicanparts.com/bmw/cata...BRKhyd_pg3.htm

  10. #25
    Join Date
    Jul 2003
    Location
    Eastern (nee Western) PA
    Posts
    4,988
    Quote Originally Posted by Mike Brendzel View Post
    Thanks for the hint. I am thinking of buying a whole set of seals and hoses for brake assembly. Does anyone sell these kits or I have to complete it by myself?
    If you are talking about the rubber lines to the wheels, those rubber parts are available off the shelf.

    If you are talking about the hard lines to the wheels, you will have to make those yourself.

    The connections to the calipers are made with soft copper washers. Nothing unusual there.

    For the master cylinder and hydraulic valve block, I know nothing about the seals. I don't think any replacement kits were ever sold. It is a high-precision assembly, so I don't think "they" wanted mechanics messing with the innards. I would like to experiment with rebuilding a MC myself, but I know I would probably destroy it, so I can't use my only one!

    I know you can get a replacement grommet for the fluid reservoir attachment point to the master cylinder. I ordered that from Pelican Parts, too. But I don't have the invoice handy for that part number. Really, unless you mess with the grommets, they don't seem to fail.

    The connections between the pump and the MC are flared lines on these vehicles, so there's no seal to replace there.

    The pump motor seals are not available from the OEM. However, if they are leaking, you can get new ones made. The shaft seal could be swapped for an off-the-shelf part, EXCEPT that I can't find anyone who stocks shaft seals of that type made from EPDM rubber. It can't be nitrile rubber, or the brake fluid will destroy it. I know where to get the proper seal in EPDM, but the minimum order is 100, and I don't want to spend $800 to have seals sit around for years. I also found someone who can make substitute oil seals out of Teflon. It works with the brake fluid, and it can be machined out of stock instead of molded, which cuts down on the minimum order size significantly. The material is harder, which may result in more shaft wear in the long run, but I don't think that's a major issue. I did some research, and I think that even the motor shaft can be replaced if it came to that. But anyway ... I have a couple of the Teflon seals sitting. I can sell you one if you really want it. If you want to hunt down an oil seal in Europe, look for a radial shaft seal, profile "BA SL" or "TC", with ID of 8mm, OD of 16mm, and length of 5.5mm (although you can use 6mm, or maybe even 7mm), made of EPDM rubber. There is also a flat circular rubber seal that seals the outer edge of the motor-to-pump connection. That shouldn't really go bad, but if it does, you can get one cut out of flat EPDM stock. I don't recall the dimensions, but you can figure that out.

    Incidentally, brushes for the motor aren't too hard to get, if you end up needing to work on it. The commutators do wear, but from the age and condition of my unit, I think they will last at least 250k miles if maintained properly. I think the commutator could even be replaced if needed, although I haven't located an off-the-shelf part yet.

    There are O-rings at the connections to the pressure switch and accumulator. These seem to last as long as the pieces they connect, so I wouldn't worry about them. If need be, you can just match up EPDM o-rings by size.

    I think that's about all I can remember for now. Let me know if I missed the point!
    God bless!!!

    1990 SC auto ... red outside, gray cloth inside ... ~205,000 miles (and climbing) ... driven daily!

  11. #26
    Join Date
    May 2012
    Location
    Lodz, Poland
    Posts
    27
    It was really comprehensive exposition Now I have to discuss it with my electrician. Thanks for the tip about replacement grommet for the fluid reservoir. I will check Pelican Parts carefully.
    Really appreciate your commitment. Many thanks!

    Quote Originally Posted by S_Mazza View Post
    If you are talking about the rubber lines to the wheels, those rubber parts are available off the shelf.

    If you are talking about the hard lines to the wheels, you will have to make those yourself.

    The connections to the calipers are made with soft copper washers. Nothing unusual there.

    For the master cylinder and hydraulic valve block, I know nothing about the seals. I don't think any replacement kits were ever sold. It is a high-precision assembly, so I don't think "they" wanted mechanics messing with the innards. I would like to experiment with rebuilding a MC myself, but I know I would probably destroy it, so I can't use my only one!

    I know you can get a replacement grommet for the fluid reservoir attachment point to the master cylinder. I ordered that from Pelican Parts, too. But I don't have the invoice handy for that part number. Really, unless you mess with the grommets, they don't seem to fail.

    The connections between the pump and the MC are flared lines on these vehicles, so there's no seal to replace there.

    The pump motor seals are not available from the OEM. However, if they are leaking, you can get new ones made. The shaft seal could be swapped for an off-the-shelf part, EXCEPT that I can't find anyone who stocks shaft seals of that type made from EPDM rubber. It can't be nitrile rubber, or the brake fluid will destroy it. I know where to get the proper seal in EPDM, but the minimum order is 100, and I don't want to spend $800 to have seals sit around for years. I also found someone who can make substitute oil seals out of Teflon. It works with the brake fluid, and it can be machined out of stock instead of molded, which cuts down on the minimum order size significantly. The material is harder, which may result in more shaft wear in the long run, but I don't think that's a major issue. I did some research, and I think that even the motor shaft can be replaced if it came to that. But anyway ... I have a couple of the Teflon seals sitting. I can sell you one if you really want it. If you want to hunt down an oil seal in Europe, look for a radial shaft seal, profile "BA SL" or "TC", with ID of 8mm, OD of 16mm, and length of 5.5mm (although you can use 6mm, or maybe even 7mm), made of EPDM rubber. There is also a flat circular rubber seal that seals the outer edge of the motor-to-pump connection. That shouldn't really go bad, but if it does, you can get one cut out of flat EPDM stock. I don't recall the dimensions, but you can figure that out.

    Incidentally, brushes for the motor aren't too hard to get, if you end up needing to work on it. The commutators do wear, but from the age and condition of my unit, I think they will last at least 250k miles if maintained properly. I think the commutator could even be replaced if needed, although I haven't located an off-the-shelf part yet.

    There are O-rings at the connections to the pressure switch and accumulator. These seem to last as long as the pieces they connect, so I wouldn't worry about them. If need be, you can just match up EPDM o-rings by size.

    I think that's about all I can remember for now. Let me know if I missed the point!

  12. #27
    Join Date
    Jul 2003
    Location
    Eastern (nee Western) PA
    Posts
    4,988
    Glad to help. By the way, I found the invoice from Pelican Parts. The part number for the grommet is 34-31-1-160-133-M4.

    Also, they have OEM brake caliper bolts. I couldn't find any aftermarket replacements that seemd to be as nice. The part number for those is 34-11-1-157-041-M4.
    God bless!!!

    1990 SC auto ... red outside, gray cloth inside ... ~205,000 miles (and climbing) ... driven daily!

  13. #28
    Join Date
    May 2012
    Location
    Lodz, Poland
    Posts
    27
    Grommet and brake fluid hose ordered.
    Big Thanks Again!

    Quote Originally Posted by S_Mazza View Post
    Glad to help. By the way, I found the invoice from Pelican Parts. The part number for the grommet is 34-31-1-160-133-M4.

    Also, they have OEM brake caliper bolts. I couldn't find any aftermarket replacements that seemd to be as nice. The part number for those is 34-11-1-157-041-M4.

  14. #29
    Join Date
    Feb 2012
    Location
    Perkasie, PA
    Posts
    66
    Hey guys,

    I stumbled upon this thread doing a search for problems with my teves. I had a leak as well and looked like it was coming from the motor housing o ring, but can't seem to find the same square sectional one. Was thinking a caliper rebuild kit might have one, but temporarily I pulled the motor off, cleaned it up and gave it an extra snug on the two allen bolts for now.

    But now I have a new problem, similar to the one that mike was having, except that the motor just runs infintely now and never seems to pressurize. Is there a special bleed procedure to prime the pump once the unit has been completely emptied? My next step is to take the unit back out and flip it upside down to fill the ball and pump housing with fluid before re-installing, but I really dont want to have to pull the unit out again right now if I don't have to for obvious reasons. Any ideas on this??

    Thanks,
    John

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