Power steering heavy - ZF pump

[ukviper]

Hi all,


I have just replaced my ZF power steering pump with a second-hand unit after the pulley on mine disintegrated.. :eek:


Although now the steering seems to be intermittently heavy at low revs.
Revving to 1500 and above, the steering is light like it was before.


I have checked and topped up fluid etc. and all seems ok.


Any suggestions? or is the pump I got on its way out?



EDIT: OK, so this seems to only happen when hot. Works normally when cold, when hot under 1500rpm = heavy steering.

Cheers.

[TheTree]

Seems like the second-hand pump may be dodgy.

I can't think of any other reason for hard steering below 1500 revs

Steve

[ukviper]

Yeah, thanks,


I had succumbed to the fact that it was the pump..
I completely drained the system and replaced with better quality fluid over the weekend, which improved it a little but still bad.


Have ordered a new pump this time.. will see how I go.


Cheers.

[Hoges]

Was the replacement pump an exact fit for the one which broke...and was the pulley on the replacement pump of the same diameter as the one which broke? If it was slightly larger then the pump pulley would be rotating a bit slower and hence the need for more revs.. normally the zf pumps are reliable...except for the dodgy pulleys on a particular batch...:mad:

[ukviper]

Hmmm.. Good point, didn't check the exact pulley size, visually, it looked the same. The pump is definitely identical to my old one. Will compare the two pulleys (well what's left of my original one..) tonight when I get home.
Thanks..

[ukviper]

Well, I have replaced with a new pump and all is good now.


Typical that I get a duff second-hand pump..


Cheers all.