Brake pedal problems

[AlexD333]

Ok so update for you chaps. As good practise and also for my knowledge I have now stripped and cleaned the rear drums, followed by the front calipers today...

I was desperately hoping somehow that the sliders would be solid and the pistons solid in mud also... Although messy this was not the case.





And the fronts today...



Slider pins still ok from Ricks visit :thumb2





Now at a loss I don't know what to check... I tried my hardest to look for vacuum hoses or anything split or damaged... Cannot see anything.... Also fluid level is ok...

Can't see this dreaded vac pump? Or don't know what I'm looking for...

Please any help appreciated :bow

I have noticed emergency stop does not really work still goes hard on first press too .... :nenau

 

[AlexD333]

I guess what I'm trying to say above is my original symptom seems to be not entirely correct, although first press can achieve some braking force it still goes hard...

 

[Lazy-Ferret]

Looking at those front rotors and pads, are you sure you have enough friction material left? My rotor was nowhere near as worn as yours, and the rivet that holds the anti-squeal spring was hitting the ridge.

It's hard to tell from the pictures, but I think that will definitely not help, although, it still sounds like a vacuum problem... did you try the test I said in my earlier post?

 

[AlexD333]

Loads of pad left, big lip on discs but defo not the issue..

Missed ur test? Just gonna have another read...

Just found this online and got me thinking as I have a squeal when turning steering?? Related?? I doubt..??

"On vehicles equipped with "Hydroboost" power brakes, a hard pedal can be caused by a loose power steering pump belt, a low fluid level, leaks in the power hoses, or leaks or faulty valves in the hydroboost unit itself (the latter call for rebuilding or replacing the booster)"

 

[Lazy-Ferret]

Here you go....

How to test brake servo...

 

[AlexD333]

Here you go....

How to test brake servo...

By depress they mean press? Confusing for sure...?

Must ask as power steering squeals like buggery, what drives vac pump? Is it a belt? If so I think I have my culprit.

EDIT - I also looked at these today, pulled off the hoses and back on? Are these related?
http://m.ebay.co.uk/itm/131408231079?nav=SEARCH

 

[terrano bob]

hi alex scrap it mate :doh only joking hope you get sorted soon :thumbs

 

[Barrbeast]

By depress they mean press? Confusing for sure...?

Must ask as power steering squeals like buggery, what drives vac pump? Is it a belt? If so I think I have my culprit.

EDIT - I also looked at these today, pulled off the hoses and back on? Are these related?
http://m.ebay.co.uk/itm/131408231079?nav=SEARCH

:doh Don't know about how the vac pump is driven but come on dude "depress"

 

[Sweety]

Must ask as power steering squeals like buggery, what drives vac pump? Is it a belt? If so I think I have my culprit.

I'm sure the servo vac pump is gear driven due to it's location under the IP but the manual will show that up:augie you have 1 belt for the P/S, 1 for the alternator & a big 1 for the AC if it's fitted but the AC belt just go's to the crank pulley where the other 2 go around crank & water pump plus the unit they need to drive:thumbs If your P/S is squealing your belt is poss shot after being covered in that sandy/mud water or somehow you got it inside the system if it's just a shot belt change the alternator 1 at the same time

 

[solarman216]

your vac pump is under the injector pump, the metal pipe runs under the engine to just behind the alternator from there it goes across the bulkhead to the brake servo, on the side of the metal pipe near the alternator is the small take off pipe to other vac stuff, pull this off and blank it (short bit of hose with a drill shank in will do) then test brakes again if all good the one of the small vac pipes or a valve have gone duff, if still the same then look for damage to the metal pipe or vac pump low effort, Rick

 

[AlexD333]

your vac pump is under the injector pump, the metal pipe runs under the engine to just behind the alternator from there it goes across the bulkhead to the brake servo, on the side of the metal pipe near the alternator is the small take off pipe to other vac stuff, pull this off and blank it (short bit of hose with a drill shank in will do) then test brakes again if all good the one of the small vac pipes or a valve have gone duff, if still the same then look for damage to the metal pipe or vac pump low effort, Rick

Brill thanks rick, I was trying to look above yesterday :lol :doh

 

[solarman216]

Cured at last

Long story so will make it short, first thing checked was vac, had none at servo so went to metal pipe rear of alternator, still no vac removed small pips that feeds the electric solenoids and put a blank on it, woo hoo vac at last, reconnect servo test brake, still the same, decided to do a proper test on the vac, so got vac gauge and put it on my motor, 27 inches no prob, put on Alex motor 27 inches no prob, so decided to swap the servo, 4 or 5 swaps later still no joy, lots of head scratching and found that you should not be able to suck on the servo point at all, Alex servo could suck a small amount , my motor cannot suck at all, went through pedal adjustments etc in case servo was being depressed slightly which would cause loss of vac but no joy, only had one servo left to try but on a non runner did not want to take it off if it was no good so used a sucker pump I have for plumbing, hooked it up to to test and was good but thought should hook it up to Alex servo and see, well while I was pumping Alex had normal pedal, so even though we got 27 inches the pump was duff, seems likely that the small pipe that was off although it was on the operation side of the electric solenoid, it must have sucked muddy water into the line, this was proven on removal of the pump, Alex has pics, this is the vac pump, it has 3 sliding vanes that stay in contact with the cylinder walls by centrifugal force, and due to the fact the rotor is off center is creates a vacuum, next pic shows the damage, sorry pics hanging so not wanting to lose this short version of text that we have done today will ignore the pics, Rick

 

[solarman216]

Alex's vac pump

 

[solarman216]

the damage that mud does to the vanes

 

[AlexD333]

As Rick says above,

This is the hose that came off, on the left


We needed steps :augie


Pipes can be moved without bleed


Those wires going to electrical doodahs above we removed all together from the vac hose and blanked as not needed (egr blanked)


Rick doing a manual pump test to replicate the vac pump.


After pump test it was confirmed dodgy vac pump, even though good reading


Oh crap :doh



Mud in banjo... Not good.


New unit courtesy of Rick :clap :bow

 

[solarman216]

the vanes can be re formed fairly easily but the bore is also scored and not so easy to sort, so suffice to say a knackered pump, Rick

 

[solarman216]

I should clarify and say that the loose plastic vanes are also sent out wards by oil pressure from the engine oil supply, Rick

 

[Sweety]

Just a quick Q on this, by removing the vac pipe to the butterfly valve on the inlet manifold won't that cause it to stop partly shut:nenau

 

[solarman216]

Just a quick Q on this, by removing the vac pipe to the butterfly valve on the inlet manifold won't that cause it to stop partly shut:nenau

Noooooooo, it is held open by the spring, vac being applied as engine shuts down supposedly to limit engine shake at that time, another useless piece of Nissan engineering, even they could not decide if it was any good or not as over the years it has been fitted some years and then not others only to be reintroduced later, may be it is emission regs or something they cannot get out of, :nenau, Rick

 

[Sweety]

Noooooooo, it is held open by the spring, vac being applied as engine shuts down supposedly to limit engine shake at that time, another useless piece of Nissan engineering, even they could not decide if it was any good or not as over the years it has been fitted some years and then not others only to be reintroduced later, may be it is emission regs or something they cannot get out of, :nenau, Rick

Thanks Rick I wasn't sure on how it worked:thumb2 only time i've seen these valves fitted is if the truck has had an egr fitted