VS V8 steering locking up

[BushTuckerNed]

Lately my steering has been locking up while giving the motor some revs.

I cant hear the belt slipping, could it be something else playing up? Pump no good?

The difference with my car is that it is the VS 5 litre motor in a Hilux with a Nissan patrol steering box .....just to confuse the situation

So if anyone has had these syptoms with a commodore and worked it out, i would like to hear.

Im just trying to elimitate possiible problems.

One thought i had was maybe the pump was not big enough to drive the GU steering box??

Any help would be awesome

Cheers

Scotty

[hako]

My first guess would be that the pump and the steering box are mis-matched and will never work successfully - the patrol box is a recirculating ball type whilst the Commodore is a rack and pinion so each needs different oil pressures and flow rates. However, if it has been working OK in the past then ignore all that I've written. Other things I'd check is whether the oil is overheating and boiling at high revs/load...Holden recommend fitting a power steering pump oil cooler for towing caravans where you have plenty of fun reversing....so maybe that's the problem. The load would have to be higher than in a Commo.

[BushTuckerNed]

yeah it worked fine before. Ive had two different steering boxes on and worked with both.

The one on now is a much bigger one tho, so maybe it eventually killed it.

I dont drive the car much either and will happen even when cold.

[marin]

Scotty, fancy seeing you here :P

You may have wanted to mention you are trying to turn 37" tyres as well LOL

I assume from what you are saying is that it is working as before at lower revs?
I had a bit of a think, and then a google search, and it seems that there is a bypass valve in power steering pumps to stop over pressurising the system and getting excessive steering assist at higher revs and potentially higher speeds where it could be dangerous, or possibly blow out your seals or a hose. It sounds like your bypass valve is opening much earlier than it should, from the way you say it only happens with revs. I'd suggest a pump rebuild after putting all this info together.

Might even be possible to shim the bypass valve a bit and get some extra assistance out of it before it bypasses, but that would be a real trial and error thing to do, but might be worth the effort if you are willing to go to the effort to play with it a bit. Just have to watch you don't go too far and blow out seals.