603/Britannia ZF Steering Box Strange Noises

[guymd]

If the engine is running, then shouldn't the steering box be under the same load as if you were driving? The difference seems to be only that the wheels aren't rolling. Perhaps the problem is something rubbing repeatedly, such as a brake rotor touching the pad as it turns, if the calliper isn't fully returning to the open position or if one rotor is a tiny bit warped. It sounds like something I've experienced with other vehicles. And it might happen only when turning in one direction. Maybe you could try spinning each front tire separately with the front jacked up, but I don't know whether it would require the weight of the car to make the noise.

[herrbartlet]

Hi,
Thank you for the input. With the wheels in the air, there is no resistance from tyre/road contact so I would suggest the steering box doesn't have to work that hard. I have subsequently repeated the 'full lock' test (engine running) with the front wheel on the ground and the noise was not present, which does then lead one to consider, as you suggest, interference with the wheels/brakes when rolling. And agreed, these noises sometimes only happen on one lock, like a worn CV joint on a FWD car. I shall try your suggestion to spin the wheels with the front jacked up, but the noise is related to engine speed and not road speed, which is why I think it's not the wheels binding.
Thanks again.

[jasa]

I assume you've checked for play in the wheel bearing?

[herrbartlet]

Hi,
Thank you for the suggestion. I don't think it's the bearings as the noise seems related to engine speed, rather than road speed. I've had the front in the air to double check for any binding, besides, it's only this week passed the MOT and my garage are really anal about front wheel bearings. It's been off the road for 4 years, so it's expected that bits seize, stick and make odd noises! More shakedown runs, I think :-)

[herrbartlet]

Result! Checked the power steering fluid and was quite dirty so the system was drained, flushed through and topped up with new. I can only assume there was an air lock or blockage/restriction due to less than spotless fluid. Thank you for the suggestions.