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  • OT: Clueless shop or troublesome problem?

    S10, 2000, 2.2l, 4.10 rear end, clutch vehicle.

    1)
    Brake pedal soft, take it is.

    Rear brake drum problem, seems fixed.

    30 days later (4 days ago), pedal INTERMITTENTLY going to floor when foot is on brakes at stoplight. Brakes feel odd much of the time. After pedal goes to floor, let up and pedal "catches" again and goes slowly to floor again, with that "squirmy" feel that is typical. Works fine sometimes.

    Take in, shop cannot find a darn thing wrong. They think everything is fine.

    I insist that is does what I have had happen. They say they can replace master cylinder for $300, but can't guarantee a fix. They don't think it is the proportioning valve because "they 99.999% leak when bad".

    2)
    clutch needs replaced at 127K.

    Same shop replaces clutch also, same time. Clutch has concentric hydraulic cylinder, they replace that, too, since otherwise it's pull the tranny again later. Clutch working fine, but starting to squeak, 127k is enough for any clutch.

    I pick it up. All OK.

    Next day, while driving to ohio, shifter will not move. Pump clutch and it releases, clutch pedal must be on floor into the rubber mat to release. Fluid reservoir is "slurping" when clutch is released.

    In Ohio, I have the system bled, and all is OK.

    About 30 days later (now) clutch INTERMITTENTLY is back to the "on the floor" biz, with hard shifting. But it will "switch back" to working fine in a matter of 3 blocks driving, then revert to "on the floor" again.

    have not taken it back for that yet, I figure they can't find anything wrong with THAT either.

    I paid 'em "some $$" for their work, and I want it fixed.

    Are they as clueless as it seems, or what?
    1601

    Keep eye on ball.
    Hashim Khan

  • #2
    Hows the fluid levels? I don't know much about cars, but it seems to me both those problems could be low fluid level letting air into the system, maybe only happening when its on a hill (or only 'fixing' itself when on a hill)

    Air in the system would also displace a little fluid, so you might end up with 'normal' fluid levels when there is air in the system, but low levels when its 'acting correctly'

    Consider just toping it up to the max acceptable levels? Its a cheap and easy fix to try.

    I also seem to recall brake fluids tend to be rather incompatable with eachother if someone refilled it recently without checking/using the exact right type.. And then theres brake fluid boiling and such.. Sure your brakes and/or clutch isent draging? Maybe check the clutch tempature if you can get at it, after idling in gear with the clutch in for awhile.. Alternatively it might not be fully engaging and sliping a little. That'd likey show up when going up a steep hill or accelerating.

    And check brake tempature after driving around without using them much.
    Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

    Comment


    • #3
      The concentric slave cylinder may be one of the all-time bad ideas in the automotive world. It's a collusion of the bean counters and the weight-reduction guys. It's a pi$$-poor design installed in the worst possible environment. It seems every vehicle they're installed on has trouble with them.

      Thank goodness for automatic transmissions.
      Any products mentioned in my posts have been endorsed by their manufacturer.

      Comment


      • #4
        Ditto on the problems with the slave cylinder. I had one on a Ford P/U. Final solution was replacement with a GM P/U with auto transmission.
        Jim H.

        Comment


        • #5
          Originally posted by Black_Moons
          I also seem to recall brake fluids tend to be rather incompatable with eachother if someone refilled it recently without checking/using the exact right type...
          Black Moons is right, DOT 3 & DOT 5 brake fluids are incompatable - If the two get intermixed they turn into a jelly kind of goo that can cause the kind of symptoms your talking about and worse.
          Dot 5 is colored (purple is what I've seen) Dot 3 is clear/amber. The cap on the master cyl. should say what's called for.
          Check the color in the reservoir.
          I cut it twice, and it's still too short!
          Scott

          Comment


          • #6
            Years ago I had a 1980 Chevy 4X4 that the brake pedal started to go to the floor. Fortunately it only happened when I came to a stop, never when actually driving. After the second time it did this, I bought a replacement master brake cylinder and swapped them out and being a curious fellow back then, I pulled it apart to have a look inside and sure enough, the rubber lip seal on the piston was worn thin on the bottom side, thin enough that it could fold over on itself and bypass fluid.

            Your brake problem might be the very same thing as mine was and a new master cylinder might be the only cure. As I recall, an aftermarket one was identical in every way to the OEM and considerably cheaper and worked flawlessly until I parked the truck.
            Location: Saskatoon, Saskatchewan, Canada

            Comment


            • #7
              'Any' time a brake pedal goes to the floor after being bled and working properly the fluid is escaping from the pressure side of the seal/piston. If the fluid is not leaking from a wheel cylinder or line, it is passing the seal/piston in the master cylinder. This indicates a defective master cylinder, whether or not it has been rebuilt or replaced with a new one. It is not too uncommon to get a bad one (or more) out of the box.
              Don Young

              Comment


              • #8
                DOT 3 VS DOT 4 Brake Fluid

                I just flushed my brake lines with new DOT 3 fluid only to find out that the master cylinder has a leak. Instead of rebuilding the master cylinder, I bought a 'newer' used MC off of ebay, but it calls for DOT 4 instead of DOT 3! D'oh! Well, I've heard that 3 & 4 are very similar and I'm wondering how thoroughly I need to flush the DOT 3 fluid out of the brake lines? Can I just 'push' the DOT 3 fluid out by adding DOT 4 to the master cylinder and pump until I think I have all of the DOT 3 out of the lines? How would you do it?

                ...Can I just 'push' the DOT 3 fluid out by adding DOT 4 to the master cylinder and pump until I think I have all of the DOT 3 out of the lines? How would you do it?

                YES. That method is just fine. Same for the routine "flushes" without requiring re-bleeding from scratch.

                I use a rubber squeeze syringe to remove most of the existing reservoir fluid, but leaving the bottom ports covered with fluid so as to avoid air entering the line. Then fill with new fresh fluid, pump it through (always leaving the bottom ports covered with fluid so as to avoid air entering the line) and repeat refilling and pumping until the new fresh fluid exits the bleeder valve.

                Brake Fluid Problems

                "I like to go with DOT 5 fluid when I rebuild the brakes, just a better product"/quote]

                Maybe not better, but certainly different. An alarm went off in my brain, so I Googled this up.

                "More than you ever wanted to know about brake fluid....

                Brake fluid facts

                By Steve Wall
                As a former materials engineering supervisor at a major automotive brake system supplier, I feel both qualified and obligated to inject some material science facts into the murky debate about DOT 5 verses DOT 3-4 brake fluids. The important technical issues governing the use of a particular specification brake fluid are as follows:

                Fluid compatibility with the brake system rubber, plastic and metal components.

                Water absorption and corrosion.
                * Fluid boiling point and other physical.
                * Brake system contamination and sludging.

                Additionally, some technical comments will be made about the new brake fluid formulations appearing on the scene.

                First of all, it's important to understand the chemical nature of brake fluid. DOT 3 brake fluids are mixtures of glycols and glycol ethers. DOT4 contains borate esters in addition to what is contained in DOT 3. These brake fluids are somewhat similar to automotive anti-freeze (ethylene glycol) and are not, as Dr. Curve implies, a petroleum fluid. DOT 5 is silicone chemistry .



                Fluid Compatibility
                Brake system materials must be compatible with the system fluid. Compatibility is determined by chemistry, and no amount of advertising, wishful thinking or rationalizing can change the science of chemical compatibility. Both DOT 3-4 and DOT 5 fluids are compatible with most brake system materials except in the case some silicone rubber external components, such as caliper piston boots, which are attacked by silicon fluids and greases.

                Water absorption and corrosion
                The big bugaboo with DOT 3-4 fluids always cited by silicone fluid advocates is water absorption. DOT 3-4 glycol based fluids, just like ethylene glycol antifreezes, are readily miscible with water. Long term brake system water content tends to reach a maximum of about 3%, which is readily handled by the corrosion inhibitors in the brake fluid formulation. Since the inhibitors are gradually depleted as. Since the inhibitors are gradually depleted as they do their job, glycol brake fluid, just like anti-freeze, needs to be changed periodically. DOT 5 fluids, not being water miscible, must rely on the silicone (with some corrosion inhibitors) as a barrier film to control corrosion. Water is not absorbed by silicone as in the case of DOT 3-4 fluids, and will remain as a separate globule sinking to the lowest point in the brake system, since it is more dense.

                Fluid boiling point
                DOT 4 glycol based fluid has a higher boiling point ( 446°F) than DOT 3 ( 446 ؛F), and both fluids will exhibit a reduced boiling point as water content increases. DOT 5 in its pure state offers a higher boiling point (500°F) however if water got into the system, and a big globule found its way into a caliper, the water would side at temperatures very much below freezing, let alone at 40° below zero, silicone's low temperature advantage won't be apparent. Neither fluids will reduce stopping distances.

                With the advent of ABS systems, the limitations of existing brake fluids have been recognized and the brake fluid manufacturers have been working on formulations with enhanced properties. However, the chosen direction has not been silicone. The only major user of silicone is the US Army. It has recently asked the SAE about a procedure for converting from silicon back to DOT 3-4. If they ever decide to switch, silicone brake fluid will go the way of leaded gas.

                Brake system contamination
                The single most common brake system failure caused by a contaminant is swelling of the rubber components (piston seals etc.) due to the introduction of petroleum based products (motor oil, power steering fluid, mineral oil etc.) A small amount is enough to do major damage. Flushing with mineral spirits is enough to cause a complete system failure in a short time. I suspect this is what has happened when some car owners changed to DOT 5 (and then assumed that silicone caused the problem). Flushing with alcohol also causes problems. Older brake systems should be flushed only with DOT 3 or 4.

                If silicone is introduced into an older brake system, the silicone will latch unto the sludge generated by gradual component deterioration and create a gelatin like goop which will attract more crud and eventually plug up metering orifices or cause pistons to stick. If you have already changed to DOT 5, don't compound your initial mistake and change back. Silicone is very tenacious stuff and you will never get it all out of your system. Just change the fluid regularly. For those who race using silicone fluid, I recommend that you crack the bleed screws before each racing session to insure that there is no water in the calipers.

                New developments
                Since DOT 4 fluids were developed, it was recognized that borate ester based fluids offered the potential for boiling points beyond the 446°F requirement, thus came the Super DOT 4 fluids - some covered by the DOT 5.1 designation -which exhibit a minimum dry boiling point of 500°F (same as silicone, but different chemistry).

                Additionally, a new fluid type based on silicon ester chemistry (not the same as silicon) has been developed that exhibits a minimum dry boiling point of 590°F. It is miscible with DOT 3-4 fluds but has yet to see commercial usage." I learned in the past thru others mistakes not to switch to DOT 5 in systems designed for DOT 3 or 4.

                Comment


                • #9
                  Yah........

                  Various random things relatd to the issues.....

                  The clutch is done fixing itself, I have to pump it now.

                  If it is leaking, the leak goes into the closed bell housing, and is unlikely to improve clutch performance......

                  Concentric cylinder seems lie a horrible idea, but the original one worked for 11 years and 127K miles. it wasn't failing when replaced, and maybe I should have had them put it in a box for me.... New one, maybe is not so good........

                  I now have the brake warning light , AND the ABS warning light on most of the time I drive. Originally, they would only come on if I released the parking brake AFTER starting the engine.... if off first, no lights. Now, both lights most of the time.

                  This has been a good truck, and I see these apparently clueless batards gros are now apparently messing it up, replacing things that do not need it, and breaking things that were not broken before.

                  Maybe I am being uncharitable?
                  Last edited by J Tiers; 09-03-2011, 11:56 PM.
                  1601

                  Keep eye on ball.
                  Hashim Khan

                  Comment


                  • #10
                    Sounds like master cylinder. It's pretty common for a worn out master cylinder to go to the floor intermittently. One thing you can do to check is to turn on engine, and then push steadily, but not too hard or fast, on the pedal. If it sinks, it's pretty well diagnostic for a bad MC. The cups are designed to expand under pressure, so when you hit the pedal hard or fast, it will usually work fine, but will leak down under lighter pressure.

                    Comment


                    • #11
                      May be..... it's what I think. I already had them replace the master cylinder...... Now I have brake and ABS lights.....

                      All I know now is that they "touched" BOTH the brakes and the clutch system.

                      And now BOTH pedals sink to the floor or are showing "system failure" lights.

                      So everything they have "touched" is failing.
                      1601

                      Keep eye on ball.
                      Hashim Khan

                      Comment


                      • #12
                        Originally posted by bruto
                        Sounds like master cylinder. It's pretty common for a worn out master cylinder to go to the floor intermittently. One thing you can do to check is to turn on engine, and then push steadily, but not too hard or fast, on the pedal. If it sinks, it's pretty well diagnostic for a bad MC. The cups are designed to expand under pressure, so when you hit the pedal hard or fast, it will usually work fine, but will leak down under lighter pressure.
                        Yea, but the outfit replaced the clutch too, and now similar problems with that too. Sounds like it's time to shop for a new shop. Sometimes you just have to cut your losses and run.
                        edit: or find a new shop AND a lawyer.
                        Last edited by Scottike; 09-04-2011, 01:33 AM.
                        I cut it twice, and it's still too short!
                        Scott

                        Comment


                        • #13
                          Originally posted by Scottike
                          Yea, but the outfit replaced the clutch too, and now similar problems with that too. Sounds like it's time to shop for a new shop. Sometimes you just have to cut your losses and run.
                          edit: or find a new shop AND a lawyer.
                          True enough, but this would also not be the first master cylinder to come out of the box defective. If it's going to the floor and not leaking, it's still the prime suspect.

                          Comment


                          • #14
                            cylinder does not have to "leak" to have this problem.. the seals can also pass fluid internally.... net result is the same... goes to floor. in a new unit it was probably damaged when made.

                            if the brake/clutch fluid reservoir is always full the I would suspect passing seals, if you need to replace/top up fluids then its leaking somewhere... if it is and there is no sign of a leak then the bell housing or vacuum assist chamber is the most likely place for fluid deposition.

                            given that the abs/brake warning light is on and you have a brake pedal/system problem you really should not be driving this on the public highway.

                            I think you need a new garage, even a trained monkey aught to be able to sort this kind of fault.

                            Comment


                            • #15
                              Originally posted by J Tiers
                              This has been a good truck, and I see these apparently clueless bastards are now apparently messing it up, replacing things that do not need it, and breaking things that were not broken before.

                              Maybe I am being uncharitable?

                              This has been my experience also.
                              Everything they broke was "weak".

                              I don't think you're being uncharitable.
                              Mike

                              My Dad always said, "If you want people to do things for you on the farm, you have to buy a machine they can sit on that does most of the work."

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