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CCKW Brake Problem


Vulture
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Gentlemen

 

Can I ask you to take a deep breath and indulge the mechanical novice that I am :n00b:. :help:

 

Brace yourself to provide some advise on the subject of CCKW brakes...

 

After 5 weeks of inactivity I started the truck this lunchtime (it's not at home currently) and was giving it a check over in preparation for possibly bringing it home this weekend. I only had a narrow time window so there wasn't going to be time to run it around, but I thought I'd move it backwards and forwards a bit and exercise the brakes.

 

Given that the brakes were fine when I used it last, I was completely taken aback when my foot went to the floor..:shocked:

Did this three times, with the engine note changing each time towards the end. I then rev'd the engine up whilst at the same time pumping the brake pedal. This firmed up to when it would normally, but as soon as I backed the revs off, the pedal went back to the floor again. That said even with the pedal on the floor I could feel that there is some breaking activity happening as I very slowly moved the vehicle backwards and forwards. There are no fluid leaks apparent.

 

Like I say I didn't have time to get into it today, but I intend to return tomorrow. Again time may be limited, and I won't have any tools with me, so what easy things can I start looking into. I will have my phone, so can take pics/video.

 

Any thoughts / ideas would be much appreciated.

 

Kind regards to all

 

Ian (aka Vulture)

 

 

P.S. Here's a pic of the old girl earlier in the year with a rather nice add-on :-)

2014-05-11___S2aDSCF4463_Snapseed__Cropped%u0025252BDrama.jpg

Edited by Vulture
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Ian

 

 

If there is smoke from the exhaust then your dumping fluid into the hydrovac, there is a small drain plug on the back of the hydrovac undo this and see if you have any fluid come out. If there is fluid then this would suggest that a seal has started to fail.I repaired one the other day,and I took almost a litre of brake flid from the hydrovac.If there is no fluid, then it might just be the big leather plunger seal is not seating or the leather has dried out. Try spraying a bit of WD40 in there from the small drain plug. The one I repaired was a type 3 single piston. could also be a split pipe or a pipe sucking in on its self. There are 3 types. Hope some of this helps. Howard

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Gentlemen

 

Can I ask you to take a deep breath and indulge the mechanical novice that I am :n00b:. :help:

 

Brace yourself to provide some advise on the subject of CCKW brakes...

 

After 5 weeks of inactivity I started the truck this lunchtime (it's not at home currently) and was giving it a check over in preparation for possibly bringing it home this weekend. I only had a narrow time window so there wasn't going to be time to run it around, but I thought I'd move it backwards and forwards a bit and exercise the brakes.

 

Given that the brakes were fine when I used it last, I was completely taken aback when my foot went to the floor..:shocked:

Did this three times, with the engine note changing each time towards the end. I then rev'd the engine up whilst at the same time pumping the brake pedal. This firmed up to when it would normally, but as soon as I backed the revs off, the pedal went back to the floor again. That said even with the pedal on the floor I could feel that there is some breaking activity happening as I very slowly moved the vehicle backwards and forwards. There are no fluid leaks apparent.

 

Like I say I didn't have time to get into it today, but I intend to return tomorrow. Again time may be limited, and I won't have any tools with me, so what easy things can I start looking into. I will have my phone, so can take pics/video.

 

Any thoughts / ideas would be much appreciated.

 

Kind regards to all

 

Ian (aka Vulture)

 

 

P.S. Here's a pic of the old girl earlier in the year with a rather nice add-on :-)

 

Ian

 

Have you checked the brake fluid level in the master cylinder?, if not suggest you start here, if the level is low and you can see no apparent leak, as Howard states the fault could be with the servo.

 

Good Luck

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Yup start with the fluid level in the master cylinder under the cab floor, if low then check all brake lines and joints all along the chassis rails and flexie hoses to drums and then the drums themselves if you can see no leaks there is only one other possibility the fluid is leaking into the hydrovac, depending on the type rex might have a kit and he might even do it for you :cool2:

 

 

Here try this

 

Various Hydrovac's.jpg

Edited by R Cubed
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Guys

 

Thanks for your thoughts.

 

Was so busy at work today I couldn't make time to get to the truck to investigate further. Very irritating to say the least:mad:. As luck would have it, after weeks of dry weather the forecast is rubbish for tomorrow with heavy rain due for most the day here in York :(. Weather permitting I'll have a look at it on Sunday.

 

Kind regards to all

 

Ian

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The 'smoke in the exhaust' is not a good indicator of a vac issue.

 

First check the master cylinder fluid level, then bleed the brakes. Your foot going to the floor is an abnormal condition indicative of air in lines or low fluid level. Make sure you bleed the system in the proper order.

 

Page 331 of the TM9 will get you started.

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In the little time I had today I checked:

 

1) The brake fluid level, which is fine, I haven't lost any,

2) For any obvious fluid leaks, there weren't any, and

3) For a collapsing hose on the pipe that goes down to the Hydovac from the engine - it looks fine.

 

I did take two small videos, and find myself non-plussed.

 

On this first one, the engine is off. I put my foot on the brake and it goes to the floor, but it will pump up.

 

[video=youtube_share;YBHGZtbr438]

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In the second video, the engine is on, and it's a similar story.

 

[video=youtube_share;gQ07oZbx6mY]

 

Howard is the drain plug your talking about the one in the middle of the back you can see in the pic I posted earlier ?

 

Wednesday' I'll get chance (weather permitting) to take it for a tiny test run (not on the public roads). We definitely have some brake action going on here, but the pedal going the floor, that's not normal is it ?

 

Kind regards to all

 

Ian

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Bleed the system. Follow the book.

 

The key is that with the motor OFF you are not getting any resistance. Without vacuum your foot is the only thing pressurizing the system.. motor off your pedal should be firm... not go to the floor. You power brakes work the same way... motor on/vacuum brakes are easy to press. Motor off/no vacuum your foot is the only thing pressurizing the system and the pedal is VERY FIRM.

 

Here is a free Bendix Hydrovac manual for you (and everyone else)

 

http://www.tm9-801.com/tm9-1827b/index.php

 

I would not drive it as is. You have no brakes.

 

My thoughts are: air between the master cylinder/vac control valve. Follow the TM to get it right.

Bad master cylinder cups

Dirt in the master cylinder reservoir that has clogged the the intake/release or equalization port.

 

Like I said, bleed the system first starting at the vac.

 

If that fails then your control valve is the next suspect. The piston may be leaking.

Edited by deadline
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Hi yep that would be the plug to undo, The other thing that may not give you a good pedal would be brake adjustment, ive known brakes to be out of adjustment,and this can affect the pedal. But as deadline says start at beginning and work back. Howard

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The master cylinder does not hold enough fluid, and the chamber is to large for any fluid to come out of the rear plug unless you have refilled the MC several times.

 

Plus the way the vac is routed, the first (closest to the front) chamber will fill up first. OP has said that the MC has not been refilled.

 

You may need to do a major brake adjustment... my jeeps pedal went almost to the floor until I did the major adjustment... but usually the pad wear is not that abrupt where one day the pedal is fine and the next it goes to the floor.

 

You can also check the brake pedal free play (about an inch).

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  • 2 weeks later...

Ian,

 

Have you done any off-roading or driving through deep water or mud recently? What you are describing could indeed be caused by a rapid and massive mal-adjustmnent of the brakes, since you have not lost fluid. I experienced similar in a GMC after wading in mud. The drums were not washed out quickly enough and the dried abrasive particles rapidly wore the linings down and the pedal became ineffective. A clean-up and re-adjust had it sorted.

 

- MG

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Ian,

 

Have you done any off-roading or driving through deep water or mud recently? What you are describing could indeed be caused by a rapid and massive mal-adjustment of the brakes, since you have not lost fluid. I experienced similar in a GMC after wading in mud. The drums were not washed out quickly enough and the dried abrasive particles rapidly wore the linings down and the pedal became ineffective. A clean-up and re-adjust had it sorted.

 

- MG

 

 

Hi Mike

 

It's a good thought, but no, I haven't done any what you would class as off-roading at all with the grey lady in the three years I've had her. I'm not counting here the odd gentle drive across some grassy fields. I treat her with kid gloves from that point of view :angel:.

 

Kind regards

 

Ian

 

2014-06-29___09.26.48-Resized.jpg

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  • 1 month later...

After weeks of rubbish weather, the sun has been out here in York. Managed to make time to get the truck home today. The brakes are working, but a huge amount of travel on the pedal, although it does come up if you pump it. Plan to bleed them this week, and re-gap the points and plugs (was a bit reluctant to start).

 

Kind regards to all

 

Ian

 

2014-11-30___13.57.04___Snapseed-Drama-Normal%u00252520%u0025255B1600x1200%u0025255D.jpg

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Silly question but with all the messing about you've done, have you reset the gap on the shoes with the snail cam adjusters on the drums?

 

 

Hi Tony

 

The short answer is no. I'm going to bleed the brakes then get hopefully get someone with better facilities then myself (which wouldn't be hard) in the new year to have all the wheels off and give the brakes a good look over and the truck a general safety check.

 

Cheers

 

Ian

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