Outer Limits 4x4 Board

Just wondering, in the general area of typical car power steering pumps, do they vary enough to raise big concerns about swapping one for another, without swapping the rest of the power steering gear?

For example, if you're swapping a bigger motor into a vehicle, is it generally going to matter much whether you use the old power steering pump or the new one? Or is it usually going to be okay to use whichever one happens to fit more easily?

Following on from that, is there any common vehicle that has a power steering pump with a remote reservoir?

most power steer pump have roughly the same flow rates, so most engine conversions dont require the pumps changed over. From momory ford use a remote res p/s pump on their V8's.
I'm no p/s guru by any means but I would asume most p/s pumps would only require a simple mod to be converted to remote res.

Thanks that's what I was getting at. Basically I have a fairly bulky, one-piece pump and have seen some smaller ones on Jap vehicles... and I may be able to make a little room in the engine bay by swapping over. The car is not even heavy enough to need power steering anyway.

I know the baleno i just ripped the engine out of has a separate pump/resovoir.

Magnas have a separate pump/resovoir too

all the new commodores vs onwards have remote, most little cars do to galants and barinas, altough barinas are electric on some models

Ruggers wrote:all the new commodores vs onwards have remote, most little cars do to galants and barinas, altough barinas are electric on some models

Hmm, electric power steering pump would be a great little space saver for me... I will have to have a squiz around for that. Do you know what models? Would it be similar flow to a belt-driven one?

He means electric assist steering, ie no hydraulics.

PJ.zook wrote:He means electric assist steering, ie no hydraulics.

Okay, but I've since found that a few cars do have electro-hydraulic power steering, ie an electric pump with a conventional rack. Honda NSX, toyota MR2, some astras, some barinas, some mazdas, some suzukis..?

Would be interesting to find out more about this anyway.

Golf and Prius have electric assist racks

P/S pumps vary in Max Pressure (crack off valve) and flow rate.

Pressure will only be a problem when you are on the steering stops, or if the wheels are jammed. Too low won't give as much MAXIMUM force, too high *may* burst something.

Flow rate will effect how fast you can turn the wheel. If the flow rate is too low, the wheel will turn normally until you exceed the avaialble fluid flow rate, then will feel heavy until it catches up.

Too high a flow rate will not be able to pass through the vave body inside the steering box and the inlet pressure will rise. This will either load the pump and cause oil heating, or with excessive flow, rise high enough to open the bypass valve. It will work, but will chew heaps of power from the engine and get very hot.

Under normal circumstances the flow is unrestricted, the steering box is basically an "open" hole and the oil jsut goes round and round. When you turn the wheel it shuts / restricts the hole and makes it do some work.

Getting pump and pipe flow & pressure specs is not too hard. Getting p/s box flow specs was damn near impossible when I tried.

None of these will effect the steering feel. That's a combination of geometry, valve setup and torque rod inside the steering box.

Paul

Just as a follow-up, the task I was working on was replacing the old GM-style power steering pump on the rover V8 with a more compact one from a Hyundai Excel. I picked the Excel one because the vehicle is very light anyway, and it had suitable fittings and the kind of remote reservoir I was after.

It's a fair bit of work building a bracket to adapt the new pump (I was adding an A/C compressor as well, hence needed more room, hence the remote reservoir), so I was scared it wouldn't work.

Anyway, it appears on first testing to work perfectly. So at least in this case the exact specs of the pump did not matter.

Updating a power steering pump to one with a remote reservoir can be useful when you are trying to add a second alternator, a/c compressor, etc, because it frees up room near the pulleys.