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+--- Forum: Brakes (https://www.superturbodiesel.com/std/forumdisplay.php?fid=11)
+--- Thread: Brake Help - Resolved (/showthread.php?tid=4156)
Brake Help - Resolved - Chuckler3 - 12-08-2012
I've been through the forums, service manuals, and the brains of my friends in search of solutions to my issues, but I have found none.
300SD - 1982
When I purchased my car, my pedal was dead until the last half inch of its range of motion. That half inch felt like a normal brake pedal and would stop the car.
I replaced the booster, and have since flushed and bled the system almost a dozen times with the same results.
I now have a pedal that goes all the way to the floor.. pumping produces some resistance, but as the pumping slows the pedal inevitably goes to the floor. My line of thinking is that it's the master cylinder. The previous owner had said that he had replaced it, but the caps on the resevoir are cracked and leaked during the pressure bleeding process. I have stopped them from leaking with some expertly placed hose clamps, but the pedal still goes to the floor. I'm prepared to order a new master cylinder, but I wanted to check here first with the collective mind to ensure proper course of action.
RE: Please Help - aaa - 12-08-2012
The calipers can also leak fluid and cause the same symptoms as a master cylinder. Look for traces of brake fluid on them. Since the master has supposedly been replaced I would focus on them first.
RE: Please Help - Chuckler3 - 12-08-2012
There has been no leaks from the brake system. The only thing that leaked was the caps on the reservoir but those have been fixed for the time being as stated above.
In what is probably an unrelated situation, there is also a wheezing noise (think about an 80 year old lifetime smoker trying to whistle) coming from the front driver's side of the motor when the brakes are being pump to check pedal feel.
RE: Brake Help - Chuckler3 - 12-08-2012
So it was the master cylinder. There was a "ball" missing in the old one as seen in the photos below.
New
![[Image: xJc8Ml.jpg]](http://i.imgur.com/xJc8Ml.jpg)
Old
![[Image: 8ePBvl.jpg]](http://i.imgur.com/8ePBvl.jpg)
Now I have to figure out this white smoke... I say this because I'm thinking it's bad rings, but I don't care to believe it. May be looking for a donor motor if this is the case...
RE: Brake Help - Resolved - Simpler=Better - 12-09-2012
Thanks for posting back with what you found-now other lurkers can hopefully fix the problem you had
As for the smoke, a valve adjustment($0-$20), timing chain stretch correction ($20 offset key+$20 dial indicator at HF), IP timing adjustment($10 JY injector line), and cleaned balanced injectors ($60-$150 depending on whether you need nozzles) would be high on my list.
Valves and injector balancing will typically yield the greatest improvement.
RE: Brake Help - Resolved - Chuckler3 - 12-09-2012
I'm actually getting a hard pedal now that I'm wishfully attributing to a vacuum leak.. It must be a small leak because the car still turns off and everything else is working fine. This line is not holding pressure and I'm hoping that's my issue.
![[Image: hYJcel.jpg]](http://i.imgur.com/hYJcel.jpg)
(12-09-2012, 02:25 PM)Simpler=Better Thanks for posting back with what you found-now other lurkers can hopefully fix the problem you had
As for the smoke, a valve adjustment($0-$20), timing chain stretch correction ($20 offset key+$20 dial indicator at HF), IP timing adjustment($10 JY injector line), and cleaned balanced injectors ($60-$150 depending on whether you need nozzles) would be high on my list.
Valves and injector balancing will typically yield the greatest improvement.
valve adjustment I'm understanding well enough. The timing chain is something else to me (offset key?? and what's a dial indicator?)... The injection pump still needs to be researched more because I've got a hefty wobble to the motor and I've read that the IP can be one of many causes... Basically what's all this mean in 5th grader talk? If you could please...
RE: Brake Help - Resolved - larsalan - 12-09-2012
http://www.peachparts.com/Wikka/OM617TimingChainStretch
RE: Brake Help - Resolved - Simpler=Better - 12-09-2012
For the brakes: was the oring between the master cyl and booster there?
The IP timing is typically set with the 'drip tube' method. You can potentially also look for the locking key thingy. You dont' have to remove the IP.
The other two IP issues are the 'fuel pressure relief spring' and the 'rack damper' adjustment bolt. Look those up.
What do your motor mounts look like? the driver's side usually disintegrates because of a diesel fuel leak.
RE: Brake Help - Resolved - Chuckler3 - 12-15-2012
The o-ring was there. The brakes worked beautifully, after the install of a new master cylinder. That is, they worked great for about 10 minutes of driving.. then the brake pedal firmed up completely. The car still stops, but it's as if I have no power assist and the pedal will only depress about a half inch to one inch. I'm hoping for time tomorrow morning to trace some vacuum lines.
RE: Brake Help - Resolved - SurfRodder - 01-17-2013
(12-15-2012, 11:15 AM)Chuckler3 The o-ring was there. The brakes worked beautifully, after the install of a new master cylinder. That is, they worked great for about 10 minutes of driving.. then the brake pedal firmed up completely. The car still stops, but it's as if I have no power assist and the pedal will only depress about a half inch to one inch. I'm hoping for time tomorrow morning to trace some vacuum lines.
the wheezing sound you listed above could be a leaky vacuum booster. That would give indication of no power assist. A small leak in the booster may still allow engine shutdown. Id get a cheapo stethoscope (HF is your friend again here) and try to isolate where the sound is coming from.
That being said, it is likely internal to the booster. Another check would be to disconnect the vac line to the booster and attach a hand vac pump (HF also, if you dont already have one...theres some nice brass body ones that are knockoffs of the Craftsman one I got years ago) and then listen to the booster as you try to draw vacuum through the supply port(engine off)...
If you have 15 bux and 15 mins you can also make a light duty vac pump from an aquarium pump as seen here:
http://www.instructables.com/id/Vacuum-Pump-from-Aquarium-Air-Pump/
(I made one of these for practicing experiments at home for o-chem lab -- works pretty good...not like a real vac pump, but a helluva lot cheaper and should be good enough to make a booster leak known).