[Closed] Vehicle Brake bleeding trouble.

What model of van? If it has ABS, and you just allowed the fluid to drain out when you changed the cylinders, it's possible you have an airlock in the ABS, which sometimes needs special 'dealer only' equipment to clear.

that sounds bad, but i'm pretty sure it doesn't have abs.
mk 1 fiat scudo el 2001

it does seem like it might have an airlock tho, as a bit of fluid is creeping through, as if round the side of the air bubble, so to speak

Some vans need plugging in to 'agitate' the ABS pump to bleed the system. However, a 2001 van may have a load sensing valve on the rear axle, connected to a valve on the brake line. This restricts brake pressure when the van is unladen. Disconnect the rod and tie it up to the highest position, this simulates full load and ensures fluid can flow to the brakes freely.

My 2005 van had a valve, my 2013 has ABS and stability control, and uses the wheel sensors to prevent wheel lock instead.

PS I use a pressure bleeder that connects to master reservoir, using pressure from the spare tyre.

ah right yes, thanks spooky, rear brake compensator. had forgotten about that. will try your tip, thanks.

so vehicles with and generally not have brake compensators then, or just depends?

I'm not sure to be honest, if the van had stability control it's got the ability to control each wheel accurately so a compensating valve is probably obsolete, and an unnecessary expense.

" swapped the rear cylinders"
Fitted new ones?
Why?
Were they leaking brake fluid?
Or were they just not not working?

If they were not working and it is not possible to push fluid through the brake pipes and hoses, then it is probable that you need new brake hoses.
Like all hoses over time they deteriorate and can get a kink in them that causes the hose to block itself preventing the flow of fluid.
Despite the outside size of the hoses, the hole down the middle / bore of the hoses is a similar size to the brake pipes. The hoses are there as flexible parts of the brake line to flex with the suspension movement, that a rigid brake pipe would not work with.
Over the years hoses just don't flex so well and then the bore of the hose gets blocked as the hose gets a kink in it.

Assuming that you are opening the bleed nipples at least a quarter turn or enough.
Either that or there is some dirt in the system somewhere, blocking the pipes / hoses.

I've never had much luck with those vacuum bleeders, they just seem to suck air in through the threads on the bleed nipples. The instructions say to grease the threads first but this doesn't work very well, or for very long.
What I have had the most success with is a Gunson Eezibleed kit. This pushes the fluid through using air pressure from a tyre. Just make sure the cap is on tight or you will make a right mess. I always add a jubilee clip around the cap as the seal is never as good as it could be.

Had the samme problem on my 2004 berlingo last week, put a new cylinder in
Vacuum pump didnt work,so I put a hose from the bleed screw in a jar of brake fluid, opened it, and pumped the pedal slowly 3or4 times, then closed the bleed screw.
Fluid started coming through straightaway, and I did it 3 or 4 times to make sure

If they were not working and it is not possible to push fluid through the brake pipes and hoses, then it is probable that you need new brake hoses.
Like all hoses over time they deteriorate and can get a kink in them that causes the hose to block itself preventing the flow of fluid.
Despite the outside size of the hoses, the hole down the middle / bore of the hoses is a similar size to the brake pipes. The hoses are there as flexible parts of the brake line to flex with the suspension movement, that a rigid brake pipe would not work with.
Over the years hoses just don’t flex so well and then the bore of the hose gets blocked as the hose gets a kink in it.

how did his fluid escape if the hose was blocked.

so, how's it going?

I always reverse fill from the slave cylinder or caliper if I've removed them or brake lines. Gets a goodly amount of fluid in the system. Then bleed in the usual manner.

thnaks everyone, i left off this job for a bit as i ordered an eazibleed type kit to try pushing through from the other side. unbelievably still no result...

i swapped the cylinders cos of a snapped bleed nipple on one of the old ones, and i'd had the back axle right off to do the bushes. so problems just compounded since then! joy.

so today i finally get round to trying the eazibleed type kit. it really didn't push any fluid through at all. and in fact when i let off the pressure it pushed back lots of old manky fluid into my nice clean stuff. GRRRR! not the first time either.

i've tried opening up the rear brake regulator too, as thought that was a good suggestion, but still no moverment.

feels like i must be missing something really obvious. but i have read that some systems need special kit. i do have a manual whaich describes the procedure as normal, apart from order back-froint-back-front.

i have done this before btw. but it was on a renault 4. so pretty straightforward

is the load compensator siezed or not - they often sieze on those vans.

When bleeding brakes the load compensator should be in the "fully loaded" position.

IIRC the comepnsator is on the rear axle just inboard of the drivers side wheel - gets alot of spray. They can also visually move but the pin can stay on seat.

IF thjat is siezed and in the unweighted position your essentially dead heading from the reservoir to the valve.