Something ain't going right ... re: bleeding MC and wheels - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

Something ain't going right ... re: bleeding MC and wheels by doonboggle on 03 Sep, 2010 22:23
Took this advice today and tried to implement it ... to the 'T' ....

Quote
With reservoir full - Bolt all 4 shut - pump pedal some at medium methodical pace - hold pedal down - release bolts a smidge - retighten bolts - let pedal up. Pump pedal - hold - release bolts a smidge - etc... "...." until you have good strait fluid pressure out of MC at all ports.

With all 4 MC outlets plugged with my metric bolts, first tried this one-by-one, wherein I'd bleed the individual MC brake line section, and once got fluid coming out, attach the metal line ... with the front brakes being the 2 first choices. Then, again individually, would go to the end of the line and implement the 'down pedal-finger plug-release-etc. until fluid came thru. With the 2 fronts, worked like a charm.
BUTT ... with the rears, following the same routine, would initially get a few drops of old fluid from the line ... and then nothing ... even though we must've pumped-release-etc about 40-50 times.

Quote
Then hook up 1 line to MC - have assistant push pedal down slow and hold it - you cap it with your finger on other end when she hits bottom - she lets pedal up - repeat .... Do that until you get good clean fluid.
Then hook that line up to its respective partner. And bleed it as normal with the bleeder screw.
Then proceed to line #2 and repeat, until all 4 are done.

Proclaiming defeat with the above, decided this section was saying to do the bleed of the MC 4 outlets all at one time, replug all 4 ... then install one line ... bleed at wheel end ... and move on down the other 3.

Again, with the (easy ones to start with) front wheels, everything went perfectly. Good clean lines of old fluid, and new fluid installed.
BUTT........ same action once to the rears. Initially, with first 2-3 pedal pumps, crudy fluid was coming out ... then no more from then on ... both sides of the rears.

So it's obvious I'm missing something........
At the end I tried connecting both rears at the same time, thinking this activity might be connected to the regulator up front ... having read in Bentley it's function of balancing out the braking between the 2 rear wheels.

Sure could us some pointers of where I'm being lost.
Thanks

[/i]
#1 by Baron VonZeppelin on 04 Sep, 2010 00:21
You've probably got blockage in the rear lines.

What did your old wheel cylinders look like on the inside ?
Were they stuck/frozen, or rusty on inside ?

Try your tire inflator to blow out the lines.
I had one rear line with blockage - my MightyVac broke it loose when it got up to about 17-18.

If you can't get it blown out the rear - then connect to the rear of line and try to blow it out the front.

If whatever ways you used worked on the fronts.
It should also work with the rears - so you have blockage somewhere. "Could" even be in the regulator.

=*= This is assuming that you are not leaving the port or line open at anytime while the brake pedal is on an upward stroke.
And that the MC is bled well. =*=

Usually, its best to start with the longest line first when flushing/bleeding.
But since these have individual lines to each wheel - its not as critical.
____________________________________________

What i meant originally was to completely bleed all 4 ports of the MC. period. (the plural tense used on bolts - ports , etc...)

[Its hard for us to remember that you've never done this before. But we're trying to keep it in layman tune best as possible.]

Then attach 1 brake line - flush it - connect it - bleed it. period.

Then go to next line. repeat.

Until all 4 lines are complete.
___________________________________
#2 by AudiVWguy on 04 Sep, 2010 00:37
I remember reading about the portioning valve might the problem. Don't know if your car has one, but if its stuck in the wrong position it can create a restriction and not let the fluid pass thru.
-JB
#3 by doonboggle on 04 Sep, 2010 00:39
Quote from: Baron VonZeppelin on 04 Sep, 2010 00:21
You've probably got blockage in the rear lines.

What did your old wheel cylinders look like on the inside ?
Were they stuck/frozen, or rusty on inside ?
Really did not look at them to any degree; just dropped them into the box of 'leftovers'.

Try your tire inflator to blow out the lines.
I had one rear line with blockage - my MightyVac broke it loose when it got up to about 17-18.

If you can't get it blown out the rear - then connect to the rear of line and try to blow it out the front.

If whatever ways you used worked on the fronts. It should also work with the rears - so you have blockage somewhere. "Could" even be in the regulator.

=*= This is assuming that you are not leaving the port or line open at anytime while the brake pedal is on an upward stroke. And that the MC is bled well. =*=
Being very diligent with this by blocking the other end with thumb ... and same with MC with the bolt plugs.

Usually, its best to start with the longest line first when flushing/bleeding. But since these have individual lines to each wheel - its not as critical.
____________________________________________

What i meant originally was to completely bleed all 4 ports of the MC. period. (the plural tense used on bolts - ports , etc...)

[Its hard for us to remember that you've never done this before. But we're trying to keep it in layman tune best as possible.]

Then attach 1 brake line - flush it - connect it - bleed it. period. Then go to next line. repeat. Until all 4 lines are complete.
#4 by doonboggle on 04 Sep, 2010 00:45
As Baron suggested, will try to blow lines out tomorrow with my dumpty-dumpty-dumpty tire inflator. It's a PITA when don't have the proper utensils or tools!!

Truck was stopping OK when I took it out for the first 'spin' couple of weeks ago ... but had the r-front sieze up ... which brought about this project of replacing major components ... and trying to get by by using difficult ones to find ... and overly expensive ... like servo for example.

Quote from: AudiVWguy on 04 Sep, 2010 00:37
I remember reading about the portioning valve might the problem. Don't know if your car has one, but if its stuck in the wrong position it can create a restriction and not let the fluid pass thru.
-JB
#5 by Baron VonZeppelin on 04 Sep, 2010 01:01
Quote from: doonboggle on 04 Sep, 2010 00:39
Quote from: Baron VonZeppelin on 04 Sep, 2010 00:21
You've probably got blockage in the rear lines.

What did your old wheel cylinders look like on the inside ?
Were they stuck/frozen, or rusty on inside ?
Really did not look at them to any degree; just dropped them into the box of 'leftovers'.

Have a look at them (old ones).
It could well be they were stuck or rusty on inside.
Which would indicate the lines were already previously clogged - and not just a current event.

It might also be good to disconnect the lines on each side of the regulator/valve - before doing a reverse current blowout.
Blowing out lines going with the current shouldn't be any problem to the reg./valve.
#6 by doonboggle on 04 Sep, 2010 02:12
Best way I can see to do it, at my end, is to connect the old front end hoses (caliper connection) in order to get some air from my tire inflator into the metal line. The inside male end not connected just may be enough to hold and get some air into it. But this will encompass a reverse mode. Now if only I can get my hands, and wrench, down to the unit to disconnect the lines.....

Quote from: Baron VonZeppelin on 04 Sep, 2010 01:01
Quote from: doonboggle on 04 Sep, 2010 00:39
Quote from: Baron VonZeppelin on 04 Sep, 2010 00:21
You've probably got blockage in the rear lines.

What did your old wheel cylinders look like on the inside ?
Were they stuck/frozen, or rusty on inside ?
Really did not look at them to any degree; just dropped them into the box of 'leftovers'.

Have a look at them (old ones).
It could well be they were stuck or rusty on inside.
Which would indicate the lines were already previously clogged - and not just a current event.

It might also be good to disconnect the lines on each side of the regulator/valve - before doing a reverse current blowout.
Blowing out lines going with the current shouldn't be any problem to the reg./valve.
#7 by Baron VonZeppelin on 04 Sep, 2010 11:15
If you have an old wheel laying around - another thing that might be worth trying -

Cut the old valve stem off - slip it over the brake line, with the line nut pushed back outta the way. Could even hose clamp it onto the line if needed. Might be worth a try, and the tire inflator would like that.
#8 by doonboggle on 04 Sep, 2010 15:39
Baron:
1. Overnite left the fronts attached ... due to having gotten fluid in both yesterday ... and bled.

2. Overnite the 2 rear lines remained attached to the MC also.

3. This morning attached old caliper hose to r-rear line at MC ... borrowed neighbors compressor ... held nozzle to end of old hose ... pushed thru 65 pounds of air thru the hose and regulator ... got gunk out of line ... and eventually nothing but air.

4. Without thinking too much, next loosened the line from the l-rear wheel in preparation to 'blow' it out.

5. But instead of doing that, decided to go ahead and push new fluid to r-rear with the pedal pump process. After 6-9 strokes, nothing was coming thru, and vacuum pull was minimal ... unlike when at the MC process.

6. When walked around to the left side, fresh fluid had been pumped out of the l-rear line previously loosened for purging. Interestingly enough, the fluid on the floor was nowhere as dark as what came out of the r-rear.

7. So now, due to clean fluid on floor, decided l-rear did not need to be purged ... so proceeded to bleed as normal with my bleeding kit.

8. Now on to the r-rear. In the configuration of all the above, there just ain't no fluid coming thru. So rehooked up purge air and had assistant do the air nozzle bit while I observed at the wheel. Nothing but good flow of air, insuring that nothing is blocking.

9. This tells me that I am still doing something wrong at the MC end. The way I read your guide is to plug all MC ports and then to, one by one, bleed a port ... and leave sealing plug in place as I move on to another port ... meaning that at the end, all 4 ports will have been bled and plugs remain in the ports.

10. So today, I have the fronts not touched since yesterday ... and presumably still OK after the bleeding process with them.

FINALE ...
so should I now 're-bleed' the 2 rear wheel ports (the most difficult ones reach on the bottom of the MC to adjust) ...
one by one and leave plugs in ...
install one line ...
pump fluid to wheel ....
bleed that wheel ...
then same process to the other wheel ? ?

Just want to make sure that fronts can be left as is from yesterday afternoon ... and will not be effected ... internally with the MC process ... if the above FINALE is correct.
Realize I am a bit dense with this ... but APPRECIATE your patience and input TREMENDOUSLY ! !

Quote from: Baron VonZeppelin on 04 Sep, 2010 11:15
If you have an old wheel laying around - another thing that might be worth trying -

Cut the old valve stem off - slip it over the brake line, with the line nut pushed back outta the way. Could even hose clamp it onto the line if needed. Might be worth a try, and the tire inflator would like that.
#9 by Baron VonZeppelin on 04 Sep, 2010 21:31
Sorry wasn't around to get back to you sooner.
I was out junkyarding all day. Then stopped by a friends house on the way home - that wants me to part out an Mk1 Jetta for him. And grabbed a few items from it.
Unloaded Truck, fed dogs, fed me, and just now cranked up the internet.

It sounds like everything is done except the right rear.
You've probably got it handled by now, but if not -

Yep, just re-purge/bleed that single port on the MC - by itself.
Leave everything else connected just as it is.

It could be that even the MC has corrosion/blockage also corresponding to that line. I would completely remove the bolt each time when purging/bleeding that port on the MC and let everything out of the way that will come out.

If after many tries it won't produce - you'll either need to take it off and take it apart and clean it up/out - or get another MC.
#10 by doonboggle on 04 Sep, 2010 22:48
Went ahead and did a total 4-port 're-bleed' process on MC ... just in cast. Come to find out, with both wife and I analyzing the problems, that I had mis-read where #4 wheel (r-rear) and #4 port is. As result, was trying to do something to the wrong port or wheel it seems.

Anyway, with the latest 4-port bleed, and then methodically keeping notes ... and doing ALL the precise steps you laid out ... I finally got pedal with all 4 wheels.

The only 3% is that in the bleeding of the cylinders on the wheels, I seemed to never actually get rid of ALL the bubbles ... small they may be, but nevertheless lots of them. So am letting pickup sit overnight, in hopes the bubbles settle into one area-void-etc ... and then re-bleed in a day or so.

Anywho ... THANKS ! ! Now to get the engine compartment pressure washed to get the brake fluid off, and also clean up the garage floor where it all dripped ... will hopefully be back on the road soon.

Quote from: Baron VonZeppelin on 04 Sep, 2010 21:31
Sorry wasn't around to get back to you sooner.
I was out junkyarding all day. Then stopped by a friends house on the way home - that wants me to part out an Mk1 Jetta for him. And grabbed a few items from it.
Unloaded Truck, fed dogs, fed me, and just now cranked up the internet.

It sounds like everything is done except the right rear.
You've probably got it handled by now, but if not -

Yep, just re-purge/bleed that single port on the MC - by itself.
Leave everything else connected just as it is.

It could be that even the MC has corrosion/blockage also corresponding to that line. I would completely remove the bolt each time when purging/bleeding that port on the MC and let everything out of the way that will come out.

If after many tries it won't produce - you'll either need to take it off and take it apart and clean it up/out - or get another MC.