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AYC ACD Pump fitted but wont bleed

13K views 15 replies 6 participants last post by  dav 
#1 ·
I dont know if im having a stupid moment or something but i have just fitted a new (second hand) ayc pump on my VII after all three lights came on the dash last weekend and fault 82 - not enough pressure.
I cant get the pump to bleed up! I can get it to power up and 'pump' but nothing comes out of the ACD but a drip...
I have also tried running the car up above 10mph's and gone left to right to bleed up the diff but that just dripped out too.

Couldnt really work it out so put the old pump back on as it was working as long as it wasnt hot and i wasnt giving it any stick. Same problem - wont bleed for ****!

The only thing i noticed that seemed a bit odd was the reservior in the boot has a small compartment in the bottom that stays empty unless i remove it and tilt it.. Either way got that filled up and it still wont bleed.

Im gonna leave it over night in case the pump is air locked or something but im not that confident.

Anybody got any ideas? :handsup:
 
#2 ·
If the system has got air into it when the pump has been removed/reinstalled then bleeding can be a little difficult. Another member M% had this same issue a couple of weeks ago. If you can't get it to bleed manually, then maybe a vist to a specialist or main dealer to use a MUT tool.
 
#4 ·
How are you tyring to bleed the acd diff you need to press the throttle pedal to the floor then turn on the ignition with the acd bleed nipple open and the pump will run and push fluid out

The rear ayc diff is bled by driving the car and turning the steering whilst opening the nipple
Yeah thats how im doing it. I reckon the evoscan bleed actuation function might do the trick better but my cable wont let that happen. I was toying with the idea of pressurizing it like you would a brake bleeder then power probing the actuators to open up the curcuit - what do you think?
 
#6 ·
OK chaps ive sorted it! This is what you have to do. The pump gets air locked so the pressure switch never sees any pressure so therefore wont open the solenoids so that fluid can flow through and bleed out of the nipples.
You have to unscrew the pressure switch from the pump then prime the pump using the throttle method. You will hear loads of frothy oil come out of the hole then followed by alot of oil (the amount can take yo quite by surprise..) also its best to only undo it half way so it 'bleeds' then re-tighten
Now the pressure switch cavity and pump are full of oil not air!

The next bit is a bit random as you woluld ahve thought you could just bleed as you do when you have had the transfer box off etc, but that wont work. The pump i had fitted was in that good nick it took only a second to prime to operating pressure so it wouldnt run long enough to bleed.
Wnat i did was open the ACD bleed screw then plug the old pressure switch in (so the ayc thought there was no pressure and ran the pump continuously)
then watch the fluid spit out of the acd bleed screw untill it turned to a steady stream.
Next go to the rear and undo the left nipple on the diff, turn the wheel to the right and prime the pump with the accelerator again - spit spit bleed, done
Then the right nipple steering wheel to the left, same again.

Disconnect the old pressure switch plug back into the new one that is on the pump and bobs your uncle!! :smthumbup
 
#9 ·
I can get you a pic but the old sensor was removed from the old pump then plugged into the loom at the back of the car. This way it only saw atmosphere pressure (it was just sat away from the pump in air), therefore carried on priming the pump even though the installed sensor was seeing lots of pressure..
 
#10 ·
Good write up in solving a common problem, but Im not a big fan of working under a car whilst all 4 wheels are turning!, and so have made up a maunual bleed activator, which I hire out for £50 for a week to MLR users, if anyones intrested.

also comes with Gauges that allows you to see what the internal pump pressure is, to see if the faults just the senor, or its the whole pump that needs changing over.

http://www.erento.co.uk/hire/vehicles-boats-aircraft/car-accessories/other-car-accessories/
 
#11 ·
Me neither. I did it with the wheels stationary. As long as the pump is running, if you turn the wheel left or right it will bleed out of the rear diff.
Basically; if you get hold of a spare pressure sensor you will never have to run the car up in the air to bleed the rear diff. And you can do the acd quicker :)

That pressure sensor is handy though to make sure its goosed before you go buying a new one..
 
#12 ·
im havein problems with bleeding the acd on my evo 7.
i took the pressure swith out half way ran the pump for a few seconds got all the air out.then i had the put power to the solenoid and then run the pump again and the bleed the transfer box,but culdnt get to bleed the back diff.so sent the car to a fella and he is sayin the pump doesant work.
if the pump doesant work why did i get it to bleed out thethe front diff.

help:goingmad:
 
#15 ·
there is 3 of us when we do it bud

1 - is in the car with engine running and doing the steering left to right whiles in gear
2- is doing the bleeds
3 - is putting power to pump and making sure pump doesn't run dry

you can do by yourself as mentioned above with out putting power to pump but does take longer :smthumbup
 
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