7.5 ton lorry brakes binding? And taking ages to get to pressure

Landcruiser

Landcruiser

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My old Leyland Daf takes several minutes when started for the brakes to get up to pressure and the alarm sound to go off. The dash display shows that cylinder 1 is worse, lagging behind cylinder 2 by about a minute. When they are finally there, I try to pull away, but quite often find I can't, releasing the air brake and revving hard in first gear but almost stalling as the brakes seem locked on. They'll then release after one or two tries, often giving me a lurchy start. Once I'm driving, this "binding" doesn't happen, but can happen again if I stop for long enough for the brake pressure to drop right down, even after the alarm has stopped and the dial shows the pressure is reached.

I had some work done on it when I bought it, but the garage advised not to touch the brake cylinders unless absolutely necessary, saying it was the seals, and once stripped down they never go back together properly. At this point I hadn't had the "binding" issue.

I can live with waiting for the pressure to build (although it's a nuisance) but the binding is a worry, not least because I'm worried I'll damage the clutch, let alone bang my horse about when it suddenly goes. Is the problem that the brakes are not ACTUALLY up to pressure and it's some sort of safety mechanism that doesn't allow me to pull away? Or something else?

Sorry this is a bit technical and specialist, I'm hoping one of the lorry mechanic people will spot it and can throw some light or advise.
 
My DAF was doing similar. Taking ages to reach pressure and loosing it quickly. If we stopped for diesel we would have to wait again. It was also doing the brake not releasing thing when it said it was up to pressure. I can't remember what the lorry mechanic said it was. But I had a new part and now it never does it. Was £200 inc fitting so not too bad. Not very technically helpful, sorry!
 
Its fairly normal on older ones, I have a 1991 Daf, as long as it doesn't take more than 3 minutes ( I think they time this at the plating! ) If its not a pain for everyone around, if you keep the revs on it will come up to pressure a lot quicker.

If they are binding, you will need the callipers taking off and regreasing as the pistons are probably sticking, I had mine done for the last plating and it cost me £50.

They do need to be used, brakes will stick otherwise, even if you take it around the block every few days it does help.
 
The pressure taking a while to get up to the point it turns the alarm off means that you have an air leak somewhere. That's what ours has got, but dad has now fixed.

to be honest i would take it to a commercial hgv fitter and get them to sort the brakes out soon as, you have no idea what's going on in the engine and what if one of the cylinders brakes while you are traveling?
 
Landcruiser said:
My old Leyland Daf takes several minutes when started for the brakes to get up to pressure and the alarm sound to go off. The dash display shows that cylinder 1 is worse, lagging behind cylinder 2 by about a minute. When they are finally there, I try to pull away, but quite often find I can't, releasing the air brake and revving hard in first gear but almost stalling as the brakes seem locked on. They'll then release after one or two tries, often giving me a lurchy start. Once I'm driving, this "binding" doesn't happen, but can happen again if I stop for long enough for the brake pressure to drop right down, even after the alarm has stopped and the dial shows the pressure is reached.

I had some work done on it when I bought it, but the garage advised not to touch the brake cylinders unless absolutely necessary, saying it was the seals, and once stripped down they never go back together properly. At this point I hadn't had the "binding" issue.

I can live with waiting for the pressure to build (although it's a nuisance) but the binding is a worry, not least because I'm worried I'll damage the clutch, let alone bang my horse about when it suddenly goes. Is the problem that the brakes are not ACTUALLY up to pressure and it's some sort of safety mechanism that doesn't allow me to pull away? Or something else?

Sorry this is a bit technical and specialist, I'm hoping one of the lorry mechanic people will spot it and can throw some light or advise.
Click to expand...

I had this issue on my 2004 Iveco and it was a leaking air pipe. You need to get it sorted ASAP really.
 
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WinkingWillow said:
I had this issue on my 2004 Iveco and it was a leaking air pipe. You need to get it sorted ASAP really.
Click to expand...

does sound like an air leak

could be a connector come loose (best case) or systematic failure of every pipe and vessel in the system (worst case and very unlikely).

best to get it looked at
 
"My DAF was doing similar. Taking ages to reach pressure and loosing it quickly. If we stopped for diesel we would have to wait again. It was also doing the brake not releasing thing when it said it was up to pressure. I can't remember what the lorry mechanic said it was. But I had a new part and now it never does it. Was £200 inc fitting so not too bad. Not very technically helpful, sorry!" (posted by Copperpot).

I'd be very interested to know what that part was! I did have a mechanic look at it, and it passed it's plating shortly before I bought it, so I'm not hugely worried about the safety aspect as in total failure or brakes suddenly coming on while driving. As I said in my original post, the mechanic said it was leaky seals in the cylinders, but not sure how this would cause the binding, which I don't think is related to the lorry standing for long periods as it will do it on a day when it's already been driven. Copperpot, I don't suppose you have any paperwork with that repair, as it sounds exactly the same issue.
 
The "binding" could just be that even though the buzzer is off the breaks have not released. Try waiting for the first air dump, (loud hiss) when tanks are properly aired up. Also get in the habit of draining your air tanks. If you look at the cylinders they will all have a ring pull on the bottom, if sludge is coming out when you drain you need to keep doing till air comes out!
 
Stupid question...where are the cylinders?

Second stupid question.....it only hisses when I apply the handbrake. Is that what you mean by "air dump?" Do you mean re-appy the brake, then let it off, then try to go?
 
I mean start it and go away for a coffee, old trucks take a long time before they are ready to move! Air pressure can only go so high before it has to release. This will make sure your pressure is off!
On an old daf the cylinders are a block of 3 near to the battery? Might involve a bit of looking under the skirts!
 
Thanks Mutley75. Next question: How do I drain the air tanks? As in "Get in the habit of draining your air tanks." Are the air tanks different to the cylinders?
 
Landcruiser said:
My old Leyland Daf takes several minutes when started for the brakes to get up to pressure and the alarm sound to go off. The dash display shows that cylinder 1 is worse, lagging behind cylinder 2 by about a minute. When they are finally there, I try to pull away, but quite often find I can't, releasing the air brake and revving hard in first gear but almost stalling as the brakes seem locked on. They'll then release after one or two tries, often giving me a lurchy start. Once I'm driving, this "binding" doesn't happen, but can happen again if I stop for long enough for the brake pressure to drop right down, even after the alarm has stopped and the dial shows the pressure is reached.

I had some work done on it when I bought it, but the garage advised not to touch the brake cylinders unless absolutely necessary, saying it was the seals, and once stripped down they never go back together properly. At this point I hadn't had the "binding" issue.

I can live with waiting for the pressure to build (although it's a nuisance) but the binding is a worry, not least because I'm worried I'll damage the clutch, let alone bang my horse about when it suddenly goes. Is the problem that the brakes are not ACTUALLY up to pressure and it's some sort of safety mechanism that doesn't allow me to pull away? Or something else?

Sorry this is a bit technical and specialist, I'm hoping one of the lorry mechanic people will spot it and can throw some light or advise.
Click to expand...


Just reading through your thread with OH who happens to be a mechanic (when he's not being a knight in shining armour....).

He sez :- Theres a dual air system on there. The main one assists the hydraulic brakes (the foot brake) the second auxiliary system is the hand brake. It's the handbrake system that isn't releasing fully. The air pressure needs to be 6.8 bar or 100psi to release the handbrake. If its showing full pressure and not fully releasing, there may be a fault with the handbrake valve. He suggests a garage to investigate this (experienced HGV garage) as it could be dangerous.
He also thinks that your air brake cylinders may be sticking. If this is the case - you can buy service exchange reconditioned units that will be perfectly good.
To drain down the air tanks (should be done every week) you will find them under the lorry, easily accessible. Theres normally a little valve that you pull to one side to remove water, muck and air. Or there could be a small tap that you turn.

He also sez that lorrys are best when driven on a daily basis or very regularly.

He also sez that women shouldn't be driving lorrys (he is also a bit sexist..) don't worry, he will be punished for that remark! lol.

Hope that was of some help.
 
Lots of help, thank you, and thank your husband too, littleshetland (after you've given him a slap). I'll have a look at those cylinders tomorrow, and get it looked at by a pro if draining the air tanks doesn't help.
 
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