Hello, I have put a Holden Astra electric power steering pump hooked up to a 1985 XJ6 4.2l, steering rack. The pump powers up gets to pressure and idles, however when I go to turn the steering wheel it aggressively goes to full left lock and continues to judder. Does anybody have any answers for me please, thanks in anticipation.
Stuart

 

I don't know exactly what part is causing the problem, but I would be looking at the pinion housing assembly. That's where the fluid is directed and managed. Has the rack ever been apart? If the answer is yes (or no), did it work correctly before you installed the electric pump? If it did, do you know what the electric pump pressure is? Does the steering wheel spin to full left lock no matter which way you turn the wheel or does it go full right when turning right also? When you say "gets to pressure and idles", what exactly is that? Is the pump a variable speed type depending on engine RPM or something else.

Dave

 

Not sure if the rack has been apart and unfortunately dont know if it was working ok before, it has not run for about 4 yrs, but I bought it off a Doctor who said it was working, (could mean anything)..The electric pump runs at 1100psi, and I am led to believe that the Jag ran a similar pressure. Yes full left lock no matter which way I turn the wheel. The pump comes up to pressure, on switching the ignition, then backs off a bit (normal for the pump). The pump is a variable speed pump, and senses pressure change internally, it draws 15a when at idle, between 15a and 35a when steering, and up to 75a at full steering lock.
Stuart

 

Stuart,
I have never seen or heard of a problem like that, but thinking through the operation of the rack it most likely is in the pinion housing assembly.

There are ports in the pinion housing that allow high pressure fluid to travel to either side of the rack rod. When the steering wheel is turned left, the spool on the pinion shaft lets HP fluid enter the port in the pinion housing that directs that fluid to the rack rod and moves it to the right which makes the wheels turn left. Same process for right turn just opposite direction. To me, it sounds like something in the spool has come loose or broke, although I can't picture what. With the pump not running can you turn the wheels left/right, although with more effort, as normal. Could the hoses possibly be reversed at the pump? The fittings at the rack are different sizes and could not be reversed. Is the wiring of the pump correct? Reversing 12+ and ground would make it run backwards. I'm really "spit-balling" here. The only other absolute tests would be to connect the hoses (electric pump) to a know good steering rack or connect the engine driven pump back to your current rack. In the first case, a favorable out come would mean there's something wrong with your rack. In the second case, a favorable out come would mean there's something wrong with the electric pump. In the first case, the test rack would not have to be installed, just positioned so that the hoses can be moved over from the current rack. Turn the pinion shaft with pliers or something.

Dave

 

For what its worth, when I re-installed the rack on my 72 E-type, all worked well until, with the engine running, I turned the steering wheel to the left, at which point it violently kicked back to the right and oscillated violently until I shut the engine down - which did not take me long! Wheels were off the ground. On my car, the connections to the pinion were the same and I had assembled it incorrectly. I swapped them and all was well! Seems like a no brainer for the two lines to have different connections, but Hey to Jaguar - you just got to love them all!
Ian

 

Ian, I think you just solved the mystery, the lines were made up before I got it, one larger fitting , the lower one has been made up for the high pressure feed pipe , it should be the low pressure return....will change them and get back to you.
Thank you...Stuart

 

Thanks Dave, I hope Ian has solved it, the lines were made up before I got it, wrongly.