Dopefish
10-21-2006, 09:34 AM
Backstory... skip to troubleshooting if this is unimportant to you
I had the day off Monday so I decided I'd go to the local Autozone and pickup a plethora of maintenance bits to work on my 240 since I've been too busy and have been neglecting it.
So I got my shopping list and was off, I intended on doing the following:
-Flush coolant system
-Change oil
-Top off or flush power steering system
-Flush transmission
-Replace front brake pads (Was down to 1mm, zOMG!) (Rear pads still have 5-6mm)
-Order TO bearing (Mine is making horrid noises due to what I believe may have been improper installation by previous owner)
So I get my parts and head home, I stop at Target to get some other stuff and decide to go ahead and top off my P/S fluid since the pump was making a little noise when turning at low speeds. So I added 1/4 a quart and it seemed a little happier and I jumped in my car and started to go, but as soon as I did I noticed my brake pedal felt weird, almost like I had a TON of air in the lines. I checked the brake fluid and it was a little low but not at MIN, so I picked up some more, added it in and no differance. I limped the car home at 10 under the speed limit out of pure fear (was only 2mi from my house) and began looking at potential problems with my neighbor.
TROUBLESHOOTING...
The fluid looked horrible so we went ahead and flushed the entire system out and added all new fluid and bled the system. The process we used started at the furthest point from the MC and worked closer to it going corner to corner. Once I had clean fluid and no more air bubbles I checked the pedal but no change. So I thought, well maybe the front pads being so low may have something to do with it, so we replaced the pads and no differance. The pedal had over 1" of excess travel before starting to slow down and I could slam it to the floor and not lock the fronts up or slow down in a safe/timely manner. The only problem I could see with how we bled it was the e-brake was left on while doing the process, but I didnt think much of it at the time. My only thought was that the MC must be bad so I ordered one from AZ and awaited its arrival. Once I got it we installed it according to the instructions, bench bleeding and all... it went on without a hitch. We rebled the system (an excessive amount of time spent at each caliper just to be SURE that there was NO air in the system). This time we assured the e-brake was off before bleeding which I think may have helped *some*.
This time, as soon as we were done bleeding the pedal feel was AWESOME, like rock solid. It felt as good as the FD brake pedal feels. So I was happy, but then we started the car and all of a sudden it was soft again with the vaccuum assist. I drove the car up to 45mph three times and tried to stop and it stopped, even was able to lock the fronts when I was all the way down on the pedal but it was still soft and lacked feedback for a large portion of the pedal travel. If I pumped it once then tried to stop the pedal feel was almost normal but it returned to being soft after 10 seconds of no brake usage.
Another strange thing is that after all of this and the MC replacement, my e-brake feeling changed. It use to have to be pulled to full extension of the handle to lock the car in place, but now I pull it up a normal amount (1/3 way) and it locks the car firmly into place and holds much stronger than it use to. I had previously adjusted the e-brake handle to fix this problem but it made little differance (over a year ago) and now all of a sudden it feels PERFECT without any adjustments...
I'm at a complete loss as to what to do next. I'm driving the car now as it does stop safely but the pedal feel is HORRIBLE and has at least an extra inch of travel before becoming firm. I began to suspect the booster but if it were failing I'd think the pedal would become harder to push down, not ridiculously soft.
Here is some information on the car in question:
1995 Nissan 240sx 5psd manual @ 215k miles
Front + rear disc brakes without ABS
Master Cylinder is a stock Nissan 7/8" Non-ABS unit
Car is powered by a KA24DE 2.4L DOHC inline-4 N/A
Using new Valvoline Sythetic Dot3/4 brake fluid
Cliff Notes for OMG long tale:
1. Brake pedal became VERY soft
2. Replaced front pads that were at 1mm and flushed and bled brake system, no change.
3. Replaced Master Cylinder with remanufactured unit from AZ
4. Rebled brake system AGAIN and AGAIN to be safe
5. Pedal feel with engine off is GREAT, when engine on, pedal feel is soft again
6. E-brake magically is working GREAT again when previously it was very weak and ineffective.
7. Me goes WTF Mate?!
_Kris
I had the day off Monday so I decided I'd go to the local Autozone and pickup a plethora of maintenance bits to work on my 240 since I've been too busy and have been neglecting it.
So I got my shopping list and was off, I intended on doing the following:
-Flush coolant system
-Change oil
-Top off or flush power steering system
-Flush transmission
-Replace front brake pads (Was down to 1mm, zOMG!) (Rear pads still have 5-6mm)
-Order TO bearing (Mine is making horrid noises due to what I believe may have been improper installation by previous owner)
So I get my parts and head home, I stop at Target to get some other stuff and decide to go ahead and top off my P/S fluid since the pump was making a little noise when turning at low speeds. So I added 1/4 a quart and it seemed a little happier and I jumped in my car and started to go, but as soon as I did I noticed my brake pedal felt weird, almost like I had a TON of air in the lines. I checked the brake fluid and it was a little low but not at MIN, so I picked up some more, added it in and no differance. I limped the car home at 10 under the speed limit out of pure fear (was only 2mi from my house) and began looking at potential problems with my neighbor.
TROUBLESHOOTING...
The fluid looked horrible so we went ahead and flushed the entire system out and added all new fluid and bled the system. The process we used started at the furthest point from the MC and worked closer to it going corner to corner. Once I had clean fluid and no more air bubbles I checked the pedal but no change. So I thought, well maybe the front pads being so low may have something to do with it, so we replaced the pads and no differance. The pedal had over 1" of excess travel before starting to slow down and I could slam it to the floor and not lock the fronts up or slow down in a safe/timely manner. The only problem I could see with how we bled it was the e-brake was left on while doing the process, but I didnt think much of it at the time. My only thought was that the MC must be bad so I ordered one from AZ and awaited its arrival. Once I got it we installed it according to the instructions, bench bleeding and all... it went on without a hitch. We rebled the system (an excessive amount of time spent at each caliper just to be SURE that there was NO air in the system). This time we assured the e-brake was off before bleeding which I think may have helped *some*.
This time, as soon as we were done bleeding the pedal feel was AWESOME, like rock solid. It felt as good as the FD brake pedal feels. So I was happy, but then we started the car and all of a sudden it was soft again with the vaccuum assist. I drove the car up to 45mph three times and tried to stop and it stopped, even was able to lock the fronts when I was all the way down on the pedal but it was still soft and lacked feedback for a large portion of the pedal travel. If I pumped it once then tried to stop the pedal feel was almost normal but it returned to being soft after 10 seconds of no brake usage.
Another strange thing is that after all of this and the MC replacement, my e-brake feeling changed. It use to have to be pulled to full extension of the handle to lock the car in place, but now I pull it up a normal amount (1/3 way) and it locks the car firmly into place and holds much stronger than it use to. I had previously adjusted the e-brake handle to fix this problem but it made little differance (over a year ago) and now all of a sudden it feels PERFECT without any adjustments...
I'm at a complete loss as to what to do next. I'm driving the car now as it does stop safely but the pedal feel is HORRIBLE and has at least an extra inch of travel before becoming firm. I began to suspect the booster but if it were failing I'd think the pedal would become harder to push down, not ridiculously soft.
Here is some information on the car in question:
1995 Nissan 240sx 5psd manual @ 215k miles
Front + rear disc brakes without ABS
Master Cylinder is a stock Nissan 7/8" Non-ABS unit
Car is powered by a KA24DE 2.4L DOHC inline-4 N/A
Using new Valvoline Sythetic Dot3/4 brake fluid
Cliff Notes for OMG long tale:
1. Brake pedal became VERY soft
2. Replaced front pads that were at 1mm and flushed and bled brake system, no change.
3. Replaced Master Cylinder with remanufactured unit from AZ
4. Rebled brake system AGAIN and AGAIN to be safe
5. Pedal feel with engine off is GREAT, when engine on, pedal feel is soft again
6. E-brake magically is working GREAT again when previously it was very weak and ineffective.
7. Me goes WTF Mate?!
_Kris