Installed a new M/C, doesn't work at all, what am I missing??

[old cool]

Buck, you never mentioned suspicion of your new MC. I'm going to assume that I'm not telling you anything new, but I've got to add a point or two. To rule out the master cyerrlinder as the problem, I would assume if you had someone push the pedal a few times, then hold it down, and then crack each line (separately) on each side of the master cylinder , you could see if it were pushing the fluid at each nut. If there is no fluid squirting at the nut, your prob is MC. If not MC, then you work your way down to the bleeders, again, having someone to press the pedal several times, then holding it and then cracking the bleeder. If your wheel cylinder (s) are not allowing the fluid to pass through, I would assume prob is malfunctioning at one or both WC. I'm sorry if this sounds insulting. But as you said it is not rocket science. And as the old high school science teacher said, test one variable at a time so you know what corrected the problem.
Looking down into a 67 style dual MC, there is a vent hole and a replenishing hole in each barrel. I dont know how your MC is built, but i would imagine the vent hole must be open for proper circulation. Please dont ask me how I know this.

[Captainfab]

I didn't go back to see if this was mentioned before, but have you checked your proportioning valve to see of the valve has slid across and blocked the ports to the front?

[luvbowties]

x2^^
sam

[luvbowties]

Originally Posted by buckroseau

Finally getting back to this. I just finished a rear axle swap out of a 97 c3500. Also all new brake hardware and wheel cylinders all the way around. So, I essentially had every brake line in the system opened up.

Bought an pneumatic bleeder yesterday and still getting my ass kicked on this now. I got fluid to start pumping out the rear cylinders with the bleeder, but I can not get anything out the front. I installed a new slave cylinder on the clutch as well and was able to get that bled out and working. But, just can not get fluid to come out the front. This isn't rocket science, at least I didn't think it was?

Matt

Matt, what happens when you attach your pressure bleeder to one opened bleeder screw at a front caliper and try to pump fluid backwards & up into the master cylinder?
Sam

[luvbowties]

I've gotta share this: about 2 months back I had a highly-modified 1960's C10 coming in to install a new master cylinder. Owner had tried, but couldn't get any pedal. He'd told me it had disc brakes from what he thought was either a 71 or a 72 C10 & had worked fine for 2 years or so. So I bought a pair of these, but Dorman brand, in advance from O'Reilly's.

>> http://www.jegs.com/p/Russell/Russel...44478/10002/-1 <<

Wanted to buy 2 for the rear also, but they had no listing for rears. Anyhow, these front ones worked like a charm, costing about $10-$12 for a pair; Dorman shows a quantity of 1, but meaning 1 pair in a blister pack.

Was quite nice to crack fronts[one at the time--didn't want to really force my luck trying both at once] a tad, go around & pump pedal twice, back under & tighten screw back up. Had the customer pump pedal while I did the rears, in usual manner. Naturally, customer did not mind the extra $10-$12, as he "kept" them, installed, when he left.

BTW/follow-up: I measured the bleeder threads on rear wheel-cylinders & ordered a pair for the rears of "our trucks", on Ebay. Will one day install these on either mine or another's truck & verify they do as well as fronts, & report back. In the meantime, I think they are also sold by Advance A/P, Jeg's, Summit's and other online sites I have not done business with. All ap's seem to hover around the 10-12$ per pair range. **Be careful, as some sites sell what looks to be identical, but for around twice the price.
Sam

[65 C20]

Have the rubber flex hoses been replaced in the last 20 - 50 years.
Even if they are not cracked on the outside they can be deteriorated on the inside and plug up. You could crack them on the down side and see if you get fluid through them while pumping.
Just a thought.
.

[buckroseau]

Ok messed around with this a bit tonight. As I said before, I can vacuum bleed the rear cylinders and get fluid to come out. But, nothing will come out the front.

I opened the line again up front where the soft line meets the hardline, right by the swing arm. I held the vacuum bleeder up against the hardline, and I could easily get fluid to pull though the vacuum bleeder. I then took my air hose and blew through the soft line while the bleeder screw was open on the wheel cylinder, air came out. So, at this point I'm thinking there is now way it can't work. Put everything back together and tried again...nothing.

Thought I would try something a little unconventional. I took the old cover off the MC and drilled a small hole in it. I then welded an air fitting to the top and hook up the air hose. I opened the air valve and pressurized the MC with the hope or thinking it would force brake fluid out the front bleeder screw. Once again, nothing. Air leaked out around the reservoir cap but nothing came out the bleeder.

As far as pumping the pedal, I tried that. It just won't build pressure so nothing I can really do with that idea.

Matt

[AcampoDave]

Sometimes when I can't get the pedal to pump up, I have a helper stab the pedal to the floor when I open the zerk. Then I close it and he releases the pedal. We repeat this and after a few rounds, enough air gets expelled to allow the pedal to pump up.

[luvbowties]

Originally Posted by buckroseau

Ok messed around with this a bit tonight. As I said before, I can vacuum bleed the rear cylinders and get fluid to come out. But, nothing will come out the front.

I opened the line again up front where the soft line meets the hardline, right by the swing arm. I held the vacuum bleeder up against the hardline, and I could easily get fluid to pull though the vacuum bleeder. I then took my air hose and blew through the soft line while the bleeder screw was open on the wheel cylinder, air came out. So, at this point I'm thinking there is now way it can't work. Put everything back together and tried again...nothing.

Thought I would try something a little unconventional. I took the old cover off the MC and drilled a small hole in it. I then welded an air fitting to the top and hook up the air hose. I opened the air valve and pressurized the MC with the hope or thinking it would force brake fluid out the front bleeder screw. Once again, nothing. Air leaked out around the reservoir cap but nothing came out the bleeder.

As far as pumping the pedal, I tried that. It just won't build pressure so nothing I can really do with that idea.

Matt

Matt, several thoughts just at random. Does the style & specs of the m/c offer enough volume to operate ALL the braking capacity your brake system, as a whole, now has? [Seems I recall you swapped in a newer rear end, like a 3/4-ton, which likely used discs on front. It also may require a much-increased volume of fluid. This should be studied carefully: "We can't very well farm 100 acres with a Shetland pony".] Did you try pumping, via mc, to see if it would pump fluid thru hard line while you had them--hard & soft lines--apart? I think this is a must at this point, just gotta be tested. Can you 'block off' rears & try bleeding just fronts? This may narrow down variables & convincingly show which end is the trouble-maker. We all tend to be blaming front for all the pain, when rears could be the source. Another test: break apart soft-&-hard line. Put a tube from soft end into jar of fluid. See if your vacuum pump will vac. fluid from jar thru soft hose & thru bleeder: I'm betting some amount it won't do it. You said and I agree only partly, subject to enclosed, suggested, further tests, "So, at this point I'm thinking there is now way it can't work," But it defies that 'fact'. Another mentioned replacing soft hoses. I agree. That's gotta be done, imo. All other lines are static--do not move/flex/bulge when fluid flows under pressure. Soft lines are dynamic/changing, as they do all 3 things hard ones don't. They do crazy things, like even rotting inside & allowing a 'peeling piece' to act as a 1-way valve & lock up one front wheel cylinder.

Your tests so far do NOT push fluid thru soft lines, just air. Tests also do not vacuum fluid thru soft lines--either all way from master OR from where you took apart one where soft meets hard.

Sorry if my thoughts seem to wander, but your problem has become mine. And I wish to cover all possibilities. At this point, my bet is on either (1)a m/c that is pumping barely sufficient volume to push fluid thru a least-resistance path which is the rear bleeders. (Blocking off front lines would verify if m/c can not only flow fluid thru rear bleeders but also operate the rear brakes with good pedal--and determine if m/c is good or bad or 'insufficient'.).......Else (2) front flex hoses are defective.

I'm following thread and looking for a soon-discovered solution.
Sam

[luvbowties]

Originally Posted by luvbowties

Matt, several thoughts just at random. Does the style & specs of the m/c offer enough volume to operate ALL the braking capacity your brake system, as a whole, now has? [Seems I recall you swapped in a newer rear end, like a 3/4-ton, which likely used discs on front. It also may require a much-increased volume of fluid. This should be studied carefully: "We can't very well farm 100 acres with a Shetland pony".] Did you try pumping, via mc, to see if it would pump fluid thru hard line while you had them--hard & soft lines--apart? I think this is a must at this point, just gotta be tested. Can you 'block off' rears & try bleeding just fronts? This may narrow down variables & convincingly show which end is the trouble-maker. We all tend to be blaming front for all the pain, when rears could be the source. Another test: break apart soft-&-hard line. Put a tube from soft end into jar of fluid. See if your vacuum pump will vac. fluid from jar thru soft hose & thru bleeder: I'm betting some amount it won't do it. You said and I agree only partly, subject to enclosed, suggested, further tests, "So, at this point I'm thinking there is now way it can't work," But it defies that 'fact'. Another mentioned replacing soft hoses. I agree. That's gotta be done, imo. All other lines are static--do not move/flex/bulge when fluid flows under pressure. Soft lines are dynamic/changing, as they do all 3 things hard ones don't. They do crazy things, like even rotting inside & allowing a 'peeling piece' to act as a 1-way valve & lock up one front wheel cylinder.

Your tests so far do NOT push fluid thru soft lines, just air. Tests also do not vacuum fluid thru soft lines--either all way from master OR from where you took apart one where soft meets hard.

Sorry if my thoughts seem to wander, but your problem has become mine. And I wish to cover all possibilities. At this point, my bet is on either (1)a m/c that is pumping barely sufficient volume to push fluid thru a least-resistance path which is the rear bleeders. (Blocking off front lines would verify if m/c can not only flow fluid thru rear bleeders but also operate the rear brakes with good pedal--and determine if m/c is good or bad or 'insufficient'.).......Else (2) front flex hoses are defective.

I'm following thread and looking for a soon-discovered solution.
Sam

Matt, just for curiosity I checked m/c's for your pickup and for '97. Seems '97 uses a 1.25"(1 1/4) bore vs. yours a 1.125"(1 1/8) bore. Comparing equal length pumps of each m/c means the '97 pumps 1.23 times as much volume of fluid as yours.

The '97's use of discs on front would dictate it pump considerably more volume. Add the use of longer strokes enabled by power brakes. [When we add boosters to our older trucks, we drill a 1.5" lower hole in brake pedal where m/c push rod attaches, giving a harder push PLUS a longer stroke to m/c for same distance pedal is depressed.] Just perhaps the '97 also uses such a longer stroke--just guessing/theorizing, as I have no clue--if it incorporates a 50% longer stroke, then the additional volume would be 1.23 X 1.50% = 1.845 times as much. Almost double the volume. Dunno if extra volume is all taken up by discs or discs PLUS '97 rears.

ALL THIS PURE THEORY, ADDED TO EVEN MORE SPECULATION, giving more............. food for thought.
Sam

[buckroseau]

Ok, this is where I'm at. Yesterday I ordered up new soft lines for the front end. Had to work today, but on the way home this evening I picked them up. After some family time, got everyone to bed I was able to sneak an hour in on this thing tonight.

I pulled the old lines out first. After I got them off I attempted to blow through them with my mouth vs the air compressor: I could not. I was able to blow through the new ones easily. At this point I'm thinking this is going to be easy. Installed the new ones, cracked the front left bleeder and hooked up the vacuum bleeder and away I went. ............nothing.

Frustrated at this point I hooked up my custom M/C cover so I could pressurize it. After turning the air on I cracked the driver side bleeder, air came out for a while then solid fluid. I closed that bleeder and then cracked the right front bleeder....nothing. I increased the air pressure a couple times and finally was able to get fluid to come out that one as well. Air for a few seconds then solid fluid. At this time I'm thinking I should be able to get some pedal pressure.....even a little. Stepped on pedal, right to floor, no resistance. I pumped it for quite a while, nothing ever changed.

I thought I would hook up the vacuum bleeder up front now just for fun, see if it will pull fluid through. Drivers side it pulled fluid through just fine. The passenger side would not pull any fluid through the vacuum bleeder.

I also wanted to try bleeding the rear again. That pulled fluid through the vacuum bleeder just fine days before, just thought I should try it again for some reason. Hooked up the bleeder...nothing. So, now I'm scratching my head wondering what's going on. I hooked up my custom pressure cover and pressurized the M/C again, fluid came out the rear solid. I closed the bleeder and gave the pedal another pump....absolutely no resistance. Pumped for a while, but still nothing.

I realize at this point I still may have some air in the lines, but I just can't believe I can't get a wheel cylinder to even move?? Or even a bit of resistance at the pedal??? The clutch is in the same reservoir and I was able to bleed that out fairly easily a week ago.

At this point I'm not sure what to try. The only thing I can think of changing out is the M/C itself.

Matt

[65 C20]

This might be a long shot.
When you are doing the vacuum bleeding or the air pressure thru the master do you have the brake pedal depressed ?
I am wondering if one of the seals or 0-rings have partially come off of the piston inside the master.
If you are taking the master off to replace, take it apart before you order another one and see if everything looks like it should.
Just a thought, you have done just about everything else.

[luvbowties]

>>You said, "Frustrated at this point I hooked up my custom M/C cover so I could pressurize it. After turning the air on I cracked the driver side bleeder, air came out for a while then solid fluid. I closed that bleeder and then cracked the right front bleeder....nothing. I increased the air pressure a couple times and finally was able to get fluid to come out that one as well. Air for a few seconds then solid fluid. At this time I'm thinking I should be able to get some pedal pressure.....even a little. Stepped on pedal, right to floor, no resistance. I pumped it for quite a while, nothing ever changed.".......This bold sentence points to possible obstruction between mc and rf wheel cylinder. System also acts as if trash is floating around inside lines, affecting both fronts and rears.<<

Why not replace the mc to hopefully correct all? Quickest test at this point.

If no joy, now, why not replace the mainline to the tee, the tee itself, and the front solid lines. Not toooo much work, but could be old front soft lines have left deteriorated remnants in the system. Would be good test to use just an elbow in place of tee, temporarily. This would allow testing mc on a "smaller system"; these lines, 50 years younger, cannot hurt. While broken apart, blow thru all lines serving front to clean out any possible debris still remaining.

Now, the new mc on the smaller system has gotta work. When verified, only you can decide whether to replace lines going to rears.
Hope some of this helps.
Sam

[padresag]

there is also a bleeding sequence to that style of m/c. left rear(drivers side), right rear, right front and then left front. furthest point from the m/c to the closest at the end. do it all in one operation. don;t do the rears and go and have supper and then come back and do the frts. make sure that you have eliminated the air at any wheel before going on to the next
ron

[buckroseau]

Progress today in the right direction! As I mentioned, decided to replace the M/C since I really didn't have much else left to look at. Ran over to O'reilly's and ordered one up. Nice thing is O'reilly's distribution center is about 35 min. from my house. So, you can buy a part at a store and pick it up right away if you want, even on Sunday.

First thing I did was bench bleed the new one! Should have done that to the other one, but had never had an issue. As soon as that was done I pulled the old one.....and right away I saw the issue. I took a pic and attached it. As you can see the brake cylinder on the M/C got pushed in about 3/4" and wouldn't return. That would explain why this whole time I was pumping and pumping and there was no pedal resistance. I played around with a bit, but it wouldn't return. I had a new one and since there not that expensive I figured I didn't want to mess around anymore. I got the new one installed and as soon as I hit the pedal I had some pressure. I was able to pump it up and hold pedal pressure fairly easily.

I attempted to vacuum bleed the lines but it just didn't work that well. It is pulling air and a little bit of fluid, but not enough. I've got family coming in over xmas so I am going to have my brother in law give me a hand pumping it up and cracking the lines the old fashion way. That's always worked in the past for me and I'm fairly certain that will work in this case.

I appreciate all the help and comments you guys offered up, that was great. I think the moral of the story here is to bench bleed the M/C's prior to installing. I think most already do, but I had never did. Not sure if it would have locked up bench bleeding, but it may have?

One other question semi unrelated to this problem. Do you guys have a copper washer on the front soft lines where the line screws into the front wheel cylinder? I got new lines and they didn't come with them. The guy at the parts counter did not show one on his computer in the parts blow out, so he said they weren't needed. The old ones I took out had them on.

Matt

[Captainfab]

Glad to hear you have found the problem. Yes I would install those copper washers where the hose threads into the wheel cylinder. That makes a positive seal at that connection.

[earl84]

What a saga. Glad you found your issue finally.

[65 C20]

Wondering if you have pulled your master apart and put a kit in it or have a replacement for it ?
Post when all is well.

[64shortbox]

I had the same problem when I installed my Disc Brakes on my truck. I couldn't get my front or rears to bleed out fluid no matter what I did so I made myself an Okie pressure bleeder and it worked great. The bad news is I was able to get everything I need from the scrap pile we have at work. I had to crank the air pressure up to almost 30 LBS though to get enough pressure to bleed everything. I know you have the stock Drum - Drum setup but I thought I would pass along the info & pictures for reference. Hope it helps though.