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bleeder rod on combination valve

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Old Feb 8, 2013 | 09:55 AM
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bleeder rod on combination valve

I'm bleeding the lines and read in the service manual that I need to depress the bleeder rod to allow flow to the front brakes. I have tried to depress the valve but it won't budge. I saw this image on another site and noticed how much the bleeder rod sticks out and wondered if the rod on the valve on the car is already depressed. Can you tell from the pictures? If it is already depressed, why might that be? Thanks.
Attached Thumbnails bleeder rod on combination valve-75-combo-valve.png   bleeder rod on combination valve-combo-valve.jpg  
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Old Feb 9, 2013 | 01:11 PM
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Re: bleeder rod on combination valve

Never had to push anything to bleed my brakes
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Old Feb 9, 2013 | 01:53 PM
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Re: bleeder rod on combination valve

Never even heard of "bleeder rod".

Of course I've only been doing this since the 60s, so I'm really just a n00b; lots left to learn about, I'm sure.

Once I get the master cyl properly bench bled and all the air out of that (since at the angle it sits at in these cars, there's several cc of cyl that's ABOVE the lines, and that's where the air goes, and NO AMOUNT OF BLEEDING EVER will EVER get air out of up there) then I usually just crack the RR bleeder screw, pop a cold one, and sit and watch until clean fluid comes out, making sure of course to regularly top off the MC so I don't have to start over; then close it up and do the same to the LR, which is MUCH quicker at that point since the line that runs the length of the car is already bled; then about that time, another cold one is required, and I repeat the process at the RF, which takes a bit of time, maybe half as long as the RR; then the LF which is SUPER quick. Pretty mcuh devoid of any hint of any actual "effort" let alone w... wo.... (OK mods, don't ban me for using 4-letter words that end with a "k") work, except for the bench bleeding part, which dimly resembles ... that ..... nasty 4-letter stuff, but only a little bit and only in a qualitative sort of way.
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Old Feb 9, 2013 | 02:12 PM
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Re: bleeder rod on combination valve

Originally Posted by jbroseorg
I'm bleeding the lines and read in the service manual that I need to depress the bleeder rod to allow flow to the front brakes. I have tried to depress the valve but it won't budge. I saw this image on another site and noticed how much the bleeder rod sticks out and wondered if the rod on the valve on the car is already depressed. Can you tell from the pictures? If it is already depressed, why might that be? Thanks.
Does the manual you are reading talk about "gravity bleeding"?

If so, then with a larger pressure spring like in the 1LE valves (The later year combo vlaves- you have an early one) the spring pressure is a little more than the non-1LE valves so as to allow for movre pressure to run to the rear brakes. This would call for either slightly loosening the bleeder nut in a gravity bleed, or you will have to manually bleed them by pumping the pedal and forcing fluid to open the spring load and put presurised fluid into the front system. Look at the graph and you can see how as fluid comes into the center chamber it goes through and presses against the spring to open more to get more pressure to the fronts. The higher this spring prssure is, the more rear brake pressure.

Jerry (JerryWho) machined a neat little threaded punger type divice for his car that allowed for a bias adjustment in place of that bleeder rod cap. This put different pressure agaisnt the back side of the spring based on screwed in length. and a jam nut on the outside to prevent unwanted turning like a rodend jam nut does. Preety nifty little device Jerry made.


What that diagram has labeled as a "bleeder rod" does not move or have any button to press. It is kindof built like a nrake caliper bleeder nut. You can also put washers between it and the spring to increase rear brake pressure.
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Old Feb 9, 2013 | 09:48 PM
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Re: bleeder rod on combination valve

Originally Posted by SlickTrackGod
Does the manual you are reading talk about "gravity bleeding"?

If so, then with a larger pressure spring like in the 1LE valves (The later year combo vlaves- you have an early one) the spring pressure is a little more than the non-1LE valves so as to allow for movre pressure to run to the rear brakes. This would call for either slightly loosening the bleeder nut in a gravity bleed, or you will have to manually bleed them by pumping the pedal and forcing fluid to open the spring load and put presurised fluid into the front system. Look at the graph and you can see how as fluid comes into the center chamber it goes through and presses against the spring to open more to get more pressure to the fronts. The higher this spring prssure is, the more rear brake pressure.

Jerry (JerryWho) machined a neat little threaded punger type divice for his car that allowed for a bias adjustment in place of that bleeder rod cap. This put different pressure agaisnt the back side of the spring based on screwed in length. and a jam nut on the outside to prevent unwanted turning like a rodend jam nut does. Preety nifty little device Jerry made.


What that diagram has labeled as a "bleeder rod" does not move or have any button to press. It is kindof built like a nrake caliper bleeder nut. You can also put washers between it and the spring to increase rear brake pressure.
The manual says, "Disc brake equipped vehicles require a manual over-ride of the front brake metering valve to permit flow to the front brakes. Lossen the forward combination valve mounting bolt and install tool J-23709 until the plunger on the front of the valve is fully depressed. Tighten the bolt and check that the plunger is held in." I've found and attached a picture of the tool. It appears that the left side bleeder rod plunger is, in fact, meant to be depressed and that the one on our car is already depressed.

So, why is it depressed? Found the following on an El Camino forum: "The old valve is "tripped" thinking the rear brakes had a failure, thus shutting off flow to them. Now you have to trick it, with master full, and lid on, have someone loosen both front bleeders, and push the brake pedal as hard and quick as you can, I call it "2 foot'n it". Don't let up until the helper tightens both bleeders, now pump it easy and slow, don't go all the way to the floor. Now try to bleed the rear." I tried this and am now able to get fluid to flow to the rear bleeder valves where before, no fluid would flow at all. That is the good news. Unfortunately, while bleeding the RR, the bleeder valve stripped so it's time to look for an answer to our new problem.
Attached Thumbnails bleeder rod on combination valve-combo-valves.png  
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