Pas - Not Working - Help!

[mrfirepro 127 1 Cars]

My PAS is not working, the steering is as heavy as on my non pas car.

 

I have all new pipes, new pump and reservoir. Have stripped the rack and rebuilt it. (really a strip clean and put back together)

 

My initial thought were that I had some pipes the wrong way round but on checking they all seem in the right places.

 

Before I go taking it all apart is there anything I can do to test any of the parts, other than that I'll try another ram and/or pinion drive.

 

any advice gratefully received

[jackherer 543]

Can you see fluid returning to the reservoir when the engine is running?

 

Does the steering get at all lighter when the engine starts or is there no assistance at all?

[mrfirepro 127 1 Cars]

Hi kieran,

 

No assistance at all, when I first started it up I saw the expected bubbles to expel all the air.

 

Should I see any visible movement in the fluid? should I be able to feel it?

[jackherer 543]

Take the return hose off of the reservoir, take the cap off and aim the hose into the reservoir then get someone to start the engine and turn it lock to lock while you check for fluid flow.

[farmer 328 1 Cars]

Was it an OE pump you used Paul?

[mikeyd 13]

with it running [or powered up if saxo pump ] turn it lock to lock several times to bleed any air out

[mrfirepro 127 1 Cars]

Thanks for suggestions.

 

Took return off and there was flow (without moving the steering), reasonable quantity but not a lot of pressure (wheels in straight ahead position), when the steering was moved the flow stopped and would not start for a few seconds, then at the end of the rack travel the flow stopped altogether.

 

The pump was new from www.msautoteile.de. back in October 2013. Car has nearly done 100 miles

[jackherer 543]

I'm pretty sure that's normal so it doesn't narrow it down. You'll have to find someone with a power steering pressure tester.

[mrfirepro 127 1 Cars]

Thanks Kieran,

 

Any idea what pressure I should expect?

[jackherer 543]

Extremely high, somewhere in the region of 900-1500 PSI!

 

I think they test the pressure by briefly closing a valve on the tester and seeing how much pressure the pump makes when it is working against the valve then with the valve open the steering is briefly held against each lock stop which should then make as much pressure as with the closed valve. The first test checks the pump and the second one checks the steering gear for internal leaks.

[ALEX 98 1 Cars]

The seals in the ram might be bust. Cant think of an easy way of testing it without removing it.

[jackherer 543]

There is no way to test it other than the method I described above AFAIK. You need a gauge and a valve to isolate the pump from the rest of the steering gear including the ram.

[mrfirepro 127 1 Cars]

Thanks for the help, have cobbled together a test rig with some hydraulic fittings, a valve and gauge all rated 300 bar so should be OK. The only issue I have is I need to get an adapter, does anyone know what size the high pressure inlet is to the pinion drive as I've decided to break the circuit there, as it's easier to get to. All my fittings are the same size as the outlet from the pinion drive.

[mrfirepro 127 1 Cars]

Got the rig up and running with the right connectors and my brand new PAS pump is dead, in fact, very dead as it was registering zero pressure.

 

Have ordered a new OE pump which hopefully will get here in the next few days.

[mrfirepro 127 1 Cars]

Fitted new OE pump today

 

 

 

Test rig setup

 

 

PAS now working, I cant say that the pressure I've seen are within the OE specs as I could find this info, but valve closed pressure was just below 1000 psi with normal running pressure at 1000 RPM was 60 psi.

 

The pressure was consistent though the range of the rack except when the wheels were at there extremities when the pressure was 1000 psi ( I guess this is the relief valve rating)

[jackherer 543]

Nicely done! Have you driven it and if so does it feel alright?