R33 GTR Active LSD bleeding procedure

[aurnob93]

Hi guys

Long story short I’ve installed a new Subframe on my Gtr at the workshop and they have failed to appropriately bleed the ATESSA system AFTER DISCONNECTING, THE LSD.

Does the LSD and the four-wheel-drive system share both the same reservoir?

And can I bleed the LSD by using the switch plug in the footWELL of the driver side of the car that is used to bleed the 4WD system?

[joshuaho96]

24 minutes ago, aurnob93 said:

Hi guys

Long story short I’ve installed a new Subframe on my Gtr at the workshop and they have failed to appropriately bleed the ATESSA system AFTER DISCONNECTING, THE LSD.

Does the LSD and the four-wheel-drive system share both the same reservoir?

And can I bleed the LSD by using the switch plug in the footWELL of the driver side of the car that is used to bleed the 4WD system?

Same reservoir but you need to also bleed the hydraulic fluid from the top of the rear diff. There are multiple bleed points in the system, you need to bleed all of them for it to work as intended. You can run the pump to bleed the system the same way as is described in the ATTESA bleed guides.

[aurnob93]

Beautiful appreciate that response !

so same reservoir that’s great.

 

do I actually have to use compressed air to the cap of the reservoir or will just activating it through the drivers footwell as is done for the Atessa system fine?

I’ve read there is a seperate plug to be disconnected for the Alsd where the pump mechanism is behind drivers wheel? Or is that false?

Yeah so the bleed nipple on top of diff and also under the LSD pump behind the driver wheel?

cheers

1 hour ago, joshuaho96 said:

Same reservoir but you need to also bleed the hydraulic fluid from the top of the rear diff. There are multiple bleed points in the system, you need to bleed all of them for it to work as intended. You can run the pump to bleed the system the same way as is described in the ATTESA bleed guides.

 

[joshuaho96]

11 hours ago, aurnob93 said:

Beautiful appreciate that response !

so same reservoir that’s great.

 

do I actually have to use compressed air to the cap of the reservoir or will just activating it through the drivers footwell as is done for the Atessa system fine?

I’ve read there is a seperate plug to be disconnected for the Alsd where the pump mechanism is behind drivers wheel? Or is that false?

Yeah so the bleed nipple on top of diff and also under the LSD pump behind the driver wheel?

cheers

 

The factory service manual mentions you can bleed the system by attaching a vacuum pump to the cap and activating the maintenance bleed mode, over about 20 minutes all air bubbles should get vacuumed out of the system:

You can also try just activating the maintenance bleed mode as described in the manual and then crack open the bleed valves in the system. I haven't actively looked for the bleeder on the diff and pump but supposedly it's in there. 

[joshuaho96]

I was looking at the rear diff section again and found the actual formal bleed procedure, if you don't have a Consult it boils down to cycling the pump with the ATTESA air bleed connector and opening the bleeder on the diff:

[aurnob93]

On 8/2/2024 at 5:59 PM, joshuaho96 said:

I was looking at the rear diff section again and found the actual formal bleed procedure, if you don't have a Consult it boils down to cycling the pump with the ATTESA air bleed connector and opening the bleeder on the diff:

Mate I love you haha I really appreciate the solid information. I’ve referred to the sticky on this topic but it’s a bit vague and outdated.

 

yeah so I’ve worked out the LSD and 4wd both work off the same core atessa pump which is located behind rear driver side wheel right? So first bleed the pump, bleed the diff, and then bleed the transfer case. Rinse repeat if required?

 

here I was under the impression that the differential had its own reservoir and pump, but in reality on the V spec, the system is combined. so I wonder if the V spec has an uprated pump system to service the LSD and 4wd?

[GTSBoy]

2 hours ago, aurnob93 said:

here I was under the impression that the differential had its own reservoir and pump, but in reality on the V spec, the system is combined. so I wonder if the V spec has an uprated pump system to service the LSD and 4wd?

If it's uprated vs anything at all, it would be the diff only pump from the RWD cars. The ATESSA pump is waaaay more beefy than what is required to run the diff. I'd suspect that adding the diff duty to it would not even make it realise that it had extra work to do.

[aurnob93]

New update

 

i followed the procedure, bled everything including diff and transfer case, plenty of air came out, car definitely feels a lot better

 

i have this new thing happening. So right after I bleed the car or I open the brown plug and it activates the pump, the level is at max line and the air gap is 5mm

 

if I leave the car sitting around un started for a day, the liquid rises back to like 3-4 above max line

 

Now with the reservoir way above max, as soon as I go open the bleed fuse, it sucks all the liquid back down to the max line

 

so is there air still in the system making it do that? Don’t see why it should rise back 

[aurnob93]

Bled the system more from reservoir and solved now 👌🏾

[joshuaho96]

1 hour ago, aurnob93 said:

Bled the system more from reservoir and solved now 👌🏾

Good to hear. Any air bubbles in the system will drastically affect A-LSD and ATTESA response time. I personally have never noticed the ATTESA reservoir doing what you said either.