gjvander

So I am in the process of re-installing the engine and transmission. I will need to bleed the hydraulic actuators that control the rear and center diff.

However, the only way to do this is to have a Bosch Hammer....

What if you just manually energized the solenoids valves. The circuit diagram indicates pins 1 and 3 energize one of the solenoids, and 2 and 4 the other one.

Are these the only valves blocking flow to the two slave cylinders?

Hopefully Adrian has an answer to this.

Regards,

Geo

Adrian

Dear Geo,
You need the Bosch hammer to do this correctly. I cannot advise you to do it any other way. I am assuming you disconnected the hydraulic lines to the differential lock slave cylinders before you dropped the engine and transmission. This was not necessary to do they could have been tied up out the way.
The reason you need the Bosch hammer is to provide some control. There is 180 bar (2600 psi) of pressure to that slave cylinder. If you try and open the solenoid valve full bore by jumpering pins and then being underneath the 964 to try and bleed the system well you could hurt yourself.
Ciao,
Adrian
964C4

gjvander

Thanks for the advice. I will let you know how it turns out. Worst case is the hydraulic fluid cuts an arm off, which is about equal with having to sell my other kidney to pay for the dealer to bleed the system.

Regards,

Geo

Adrian

Dear Geo,
Should only take 15 mins, 30 mins at most. This includes set up time. The hammer can be hooked to the 19 pin diagnostic port for this job.
Ciao,
Adrian
964C4

Jeff Midili

Adrian,
This brings up a good question I was wondering about for a while:

If a C4 owner wants to do some work on their car that involves removing the engine like the clutch, or anything else that requires the Hammer to put back together, can the engine be re-installed and then have the car towed to a dealership to do whatever Hammer work is required?

Regards,
Jeff

Adrian

Dear Jeff,
If you do the engine and transmission removal and installation work correctly (procedure in my book that explains this) you do not need the hammer for a C4. The only time you need the hammer is when you get into disconnecting hydraulic lines. You do not need to disconnect hydraulic lines unless you are specifically repairing that area of the system. I have actually worked out various ways to avoid using the hammer with a C4. In the early days when we had no data and no procedures it was always "use the hammer". Some years later and a few procedures worked out hammer usage is reduced to a minimum. It is all in my book.
Ciao,
Adrian
964C4

Jeff Midili

Excellent news Adrian,

I can't wait for the book to be available (not that I'm taking my engine out anytime soon!).

Regards,

Jeff