New doubt about brakes.

[Fernando Mendes]

http://img98.imageshack.us/i/imagem337b.jpg/
Material that I used to get smooth and brightness.

[Fernando Mendes]

http://img80.imageshack.us/img80/6268/imagem337.jpg
http://img375.imageshack.us/img375/686/imagem338g.jpg
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Material that I used to get smooth and brightness.I had to change the vacuum valve spring with a similar.I am trying to put the clip, but it is very difficult.I have to lower the rubber gasket to allow enter the clip.

[Fernando Mendes]

http://img195.imageshack.us/img195/8588/imagem338.jpg
http://img810.imageshack.us/img810/3144/imagem339.jpg
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http://img19.imageshack.us/img19/4406/imagem342q.jpg
Two days believing,lowering the circle rubber gasket and clip too,to give space to enter the clip.Finally I got....finally!!!

[Fernando Mendes]

http://img13.imageshack.us/img13/6261/imagem335o.jpg
http://img3.imageshack.us/img3/6268/imagem337.jpg
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Last pics before the conclusion of hydrovac restoration.Today was rubber gasket.

[Fernando Mendes]

http://img222.imageshack.us/i/imagem336.jpg/
Hydrovac reinstalled yesterday.
Now I will check the check valvein the intake manifold.Check all hose clamps tight.

[Fernando Mendes]

http://img708.imageshack.us/i/imagem335.jpg/
Today I dismounted the check valve and I became surprised with I saw.The valve was prisoned in their upper and lower body and its gasket burned.I put a asbesto gasket now.

[Fernando Mendes]

Fernando,
I had exactly the same problem. First I thought the brake cylinders were clogged or the brake shoe return spring was weak. So I checked everything. Springs were strong and in good order. Cylinders were a bit stained but not much. I cleaned them thoroughly. The problem still existed.
So I checked the brake hoses. My truck is a last series made vehicle. So the brake lines and hoses are completely different to its predecessors. The two rear axles have only ONE break hose each. They are not fixed to the wheel backing plates. These are all steel lines. The two hoses are installed at the center of the axles near the differential housings. The hoses are running along the suspension near the housings and are CLAMPED on it. And that was the problem! The preowner screwed these clamps much too tight and squeezed the hoses. When applying the brake, force was strong enough to squeeze brake fluid through the hoses. But upon release of the brake pedal the fluid could not flow back. Rear brakes still applied and released very slow as the brake fluid "dripped" back. Front brakes were completely released of course. I screwed open these clamps a bit and I could hear the brake shoes returning to open position with a gentle screeching noise.

Regards,

Chris

Chris yesterday,after hydrovac restoration,I was reading the page 12-6 of the TM10-1563,BRAKES,letter F.Master Cylinder Adjustment-Master cylinder piston and push rod MUST RETURN TO FULL RELEASED POSITION WHEN BRAKES ARE RELEASED.If push rod does not return fully,fluid by-pass port in master cylinder WILL BE COVERED BY PISTON CUP;thereby PREVENTING FLUID FROM ENTERING MASTER CYLINDER BARREL.Refer to figs.1 and 7 proceed as follow:
1.Loosen lock nut(10) at push rod(9),using one wrench on push rod and other on nut and TURN ROD UNTILL PISTON TOUCHES STOP PLATE in end of master cylinder.Tighten lock nut.
2.When push rod adjustment has been completed,measure clearance between lever(6) and stop screw(43).This measurement should be .020" and must be measured with return spring attached so that pedal and controls are in fully released position.Excessive clearance at this point will cause piston to strike stop plate when brakes are released,while no clearance will cause piston cup to cover fluid by-pass port in master cylinder.
Good luck.FERNANDO MENDES.

[Chris_M]

Yes Fernando. I read that too and checked the clearence before I discovered these squeezed brake hoses. The master cylinder is new and everything is in good order. Problem is solved (at least partially). Now I have the problem, that air gets into the lines. I don't know why yet. There is no brake fluid leaking. Maybe these formerly squeezed hoses are cracked somewhere. I am going to replace them. I hope this solves it.

Regards,

Chris

[Fernando Mendes]

The most important now I sad is lock nut and push rod.Your fluid by-pass port in MC is too beeing covered by piston cup.

[Fernando Mendes]

http://img828.imageshack.us/img828/6268/imagem337.jpg
http://img830.imageshack.us/img830/8588/imagem338.jpg
Hi Chris.Today I loosened (pic 337-before,pic 338-after)the lock nut at push rod and turned rod a few of turns(in counterclockwise) untill or almost piston touches the stop plate,rod was all rusted inside,I put engine oil.I stay still with a doubt: doing this procedure;after pedal pressure and released;.... opening the filler cap of MC immediately we will see more bubbles inside or minus? In other way my question is:piston returning to full released position when brakes are released,means MORE or MINUS bubbles inside the master cylinder after opened the filler cap?