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Thread: Help required urgently! Arapahoe brakes Reply to Thread
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  Topic Review (Newest First)
06-12-2016 03:16
Pudsey_Bear As you want to change vans, I would be inclined to PX it at a decent dealers for one you like, mention they will need to come look at it has been unused for a while and the brakes have seized, on, but leave it at that, they will assume a simple fault, and possibly give you good deal if the rest of the van looks good, and the problem is then theirs to sort out, they are the professionals so let them figure it out, or you could get Motorhome Depot (sorry) so sell it on your behalf.
05-12-2016 19:02
erneboy He's replaced shoes and cylinders Ken, so not discs on the rear.
05-12-2016 18:54
gaspode I'm presuming that you are aware that when fitted with rear disc brakes these Fiats are fitted with "top hat" hand brakes?
This simply means that the handbrake works inside a drum which is completely separate and independent from the rear (disc) brakes.

If you're not aware of this then you need to check out the mechanically operated handbrake shoes which are concealed inside the drake disc forging (completely independent of the hydraulic system) as these are very prone to sticking if not correctly adjusted. Many people and garages adjust the handbrake incorrectly via the cable rather than the inner cams and this can very easily lead to the shoes seizing on the drums both when parked up with the handbrake on AND during normal travel.

Apologies if I'm trying to teach you to suck eggs.
05-12-2016 18:27
cabby You do not say if the front wheels are locked or not, if they are not then the master cyl is not the cause.
I myself would ask if the rear brake compensator is at fault.I seem to remember from my distant past about the rear axles dropping beyond a certain point when jacked up activated this valve, You could clamp the rear flexible bake hoses, release the pressure by undoing the bleed nipples and see if the wheels turn.

cabby
05-12-2016 17:49
admiral halsey Sorry, we have a Fiat Ducato 2.8 based MH.

We have decided to trade her in because:
she's 16 years old, I don't have the funds to garage her every time she's ill, plus I cannot keep intruding on my brother's good will(he says he's getting to old to be doing mechanics!)

She is also too big for our needs really. When I bought her, we envisaged some holidays with our teenage kids, but that didn't happen. So I find myself dragging around an 8m, 6berth MH, when a 6m, two berth one would suit us just fine.



AH
05-12-2016 17:14
erneboy It may not be the back brakes causing the problem. I've had collapsing innards on flexible pipes before now, as already suggested. Loosen a nipple to see if that's it.

Here's another thought. There's a well known problem with some Brembo callipers which have phenolic pistons. They are made from a cast resin which can absorb moisture from the air and become stuck. Bear in mind that I have no idea who makes the callipers for Fiat. I've never heard of that problem effecting Fiats but it might be worth investigating.

Read the bit about pistons about 1/3 way down the page here http://www.aa1car.com/library/brake_calipers.htm

Unlikely perhaps but you never know. Brembo are Italian and may supply Fiat, or have done at some time, I don't know. Other manufacturers, possibly Fiat may also use phenolic pistons.
05-12-2016 17:05
Mrplodd You have not specified what make of vehicle your MH is based on which would help people to give you a better answer.

For my part I would suggest that you look under the dash and see if the pushrod that is attached to the brake pedal has any form of adjustment on it. It's possible that the lock nut has come loose allowing the pushrod to extend slightly and thus keeping pressure in the hydraulic system (and keeping the brakes on) Your explanation of the brakes staying on after you applied them tends to point to this possibly being the problem.

As others have said you need to approach this in a logical sequence to identify excatly where the problem lies.

First step is to find out if the problem is on a single wheel, or axle or all of the wheels.

If it's just a single wheel then that's where to problem is. (Wheel cylinder or front caliper seized or, if a rear wheel possibly the handbrake being stuck on)

If it's on ALL the wheels then refer to my first suggestion. The way to check would be to release one of the brake bleed nipples to ensure there is no residual pressure in the hydraulics. If the problem then goes away it's proof that there is pressure being held within the hydraulic lines. Again try the brake pedal push rod adjustment, if it's not that then the master cylinder is starting to look suspect.

Like i said, approach this in a logical sequence and you will soon identify the fault.

I doubt if the problem is particularly difficult to sort out once you know what is causing it and it will certainly be a lot cheaper than changing your MH!

Andy
05-12-2016 16:32
admiral halsey
Quote:
Originally Posted by flyinghigh View Post
if the master cylinder is holding on the rear brakes just crack open a rear bleed nipple, if it squirts out and doesn't just dribble then it's likely the master, but i have had a few flexible brake pipes collapse internally that will also cause the rear brakes to bind, admit-tingly that's over a lifetime in the motor trade,
the rear brake compensator valve usually seized fully open causing the rear brakes to lock before the fronts, you can always clamp the flexible brake pipes one at a time to pin point the problem,
My brother and I changed the ALKO valve earlier this year, and fully bled the brakes. I don't recall the strength of the squirting from the bleed nipple. In that instance the ALKO valve replacement seemed to do the trick. I don't recall any concern at that time about the flexible pipe. My brother has had to undo, and re-bleed these connections with regard the replacement cylinders a couple of weeks ago. Again, he expressed no concern about them then.

The odd thing about the ALKO valve, when we replaced it, was that you could see right through it. There didn't appear to be a valve bearing in it. After the fix the old girl seemed just fine and caused no problems in Brittany in the summer.

AH
05-12-2016 16:21
flyinghigh if the master cylinder is holding on the rear brakes just crack open a rear bleed nipple, if it squirts out and doesn't just dribble then it's likely the master, but i have had a few flexible brake pipes collapse internally that will also cause the rear brakes to bind, admit-tingly that's over a lifetime in the motor trade,
the rear brake compensator valve usually seized fully open causing the rear brakes to lock before the fronts, you can always clamp the flexible brake pipes one at a time to pin point the problem,
05-12-2016 16:21
admiral halsey Thanks for the replies.

Despite not getting away, I try to give the old girl a drive at least once a month. She's been stationary since half term, when she was bought back on the low loader. Initially the brakes seemed free, having cooled down.Thus, I was able to park her in her allotted space. Since then, she has had all the wheels off and the engine running, though she hasn't moved again since the initial parking.

The lock-up is on rough, but level ground, so I don't feel the need to yank the handbrake on hard. I'm certain that if the brakes are locked on under any circumstances, she will not budge from standing still. I know, I've tried several times(in both forward and reverse).

Whilst on the A road a few weeks back, I obviously touched the brakes and they failed to release. As I was travelling at 50+ MPH, they cooked, rather than brought me to a stop.

AH
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