Noisy steering servo pump

[swedane]

My 1997 XK8 have an intermittent LOUD knocking comming from the left side of the engine. First I suspected the VVT gear (timing chains and tensioners uppgraded to latest version), but now I found that this terrible metallic sounding knock varies when I turn the steering wheel. It actually stops for a couple of seconds if I get the steering wheel in the "right" position.

The fault must be within the steering servo pump or????? Any ideas before I order the rather expensive pump much appreciated.

Thanks
Arne

[mike020150]

Hi Arne,
As ever, diagnosing noises remotely is a tough task, even more so when the noise is intermittent and cannot be reproduced at will. Assuming the steering fluid level is correct and there are no leaks, my first inclination would be to check that no mounting bolts for the ancillaries have worked loose or been lost before condemning the pump. Can you get a stethoscope or a piece of wood (to transmit the noise to your ear) to the pump when the noise occurs? If so, it should be possible to confirm your diagnosis or to eliminate the pump as the source of the noise. I have known loose pulley wheels, including the crankshaft pulley to create similar issues. Mike.

[swedane]

Thanks Mike for Your suggestions - You were right.
I checked the ancillaries and soon found out what was wrong. The power steering pump pully had lost one bolt and I could unscrew one with just my fingers. The holes in the pully had become oval and the pully knocking at the remaning bolts made the terrible noise. I have ordered a new pully and new bolts and my XK8 will soon be out on the roads again.

Arne

[GrandTourer]

Always great to hear of a result

[mike020150]

I'm very old fashioned and believe in always checking the simple things first. It produces results more often than not! Glad it worked this time. Mike.