Hydraulic Pump Knocking

[willg54]

Been a while since I've posted here, but I'm still kicking about!

Finally got the audi back to the body shop for a ceramic coat, ashamed with myself it's only done 60miles in 2 years... Anyway...

I fitted a new hydraulic pump a while back which started knocking loudly quite soon after. It was a Chinese copy so I got a genuine refurbed one but on the drive this has started doing the same within about 40 miles of use.

Anyone think of a cause for this? Something seems off with the system somewhere. Steering feels fine, it's had a new accumulator a while back too that's working fine. Running on the green hyd fluid (if I remember correctly).

[newsh]

Have you replaced any pipes? IIRC One of the pipes to the rack has a restrictor in it and a special shape to stop it knocking, if you get the pipes repaired or replaced they can leave the restrictor out.
I remember A80Avant having issues with this. Worth checking his project thread but it’s gonna be a long read!

[willg54]

Hey Newsh!

I did replace one whilst doing my main rebuild, can't remember which one off the top of my head. It was a genuine part I think. Cost a fortune! I'll have to take a look. Sounds like it could be the issue.

[willg54]

Reckon it was pump to rack that got changed.

[K Simmonds]

That's the one with restrictor in it, well I'm pretty dam sure it is.

Odd that it only does it after 40 miles, I guess the fluid gets quite a bit thinner as it warms up which could explain that.

I've never had a look to see if that restrictor is removable or not as I've never needed to, perhaps the new hose came without it and it's listed as separate part?

[willg54]

Looks to only have a single part number, can't see how it would come out though.
When I'm home ill try and hunt the old one, doubt I'll have thrown it away.

Also got a feeling I put copper washers on the fittings, this wouldn't help as it'll misalign the banjo with the internal flow of the banjo bolt. Hate not being able to quickly check!

[K Simmonds]

Be interesting to know as I can't really see how you'd be able to remove anything of any substance from the hose with the ends on.

If it does it with two pumps it has to be something else, unless your extremely unlucky, But I really doubt a genuine refurbed pump would be the cause, the Chinese copy yes but not one that's the real deal.

Was it you who rebuilt my rack for me years ago? Pretty sure it was... It's my spare now for my RS2.

[SteveH]

Do you still have the cooler pipe in place between the reservoir and pump? If the fluid gets hot it can cause additional noise and loss of power in the system. Doubt it would happen within 40 miles unless the ambient temps are high. Mine gets noisy and steering assist reduces after a good track session. Once it cools down it's back to normal.

[nribs]

Low fluid? Seems too easy, but worth checking. The reservoir is incredibly difficult to gauge since it's not transparent.

[simons2]

Reservoir has a low level sensor , have you taken the belt off to prove it is the pump ? noise travels in weird ways on an engine

[nribs]

Reservoir has a low level sensor , have you taken the belt off to prove it is the pump ? noise travels in weird ways on an engine

Indeed there is a low level sensor, but the pump can become "unhappy" long before it will throw the sensor light.

Unhappy pump either is running with air in system (odd because it self-bleeds once correctly filled with fluid).

Upon more thought I'm wondering if the x-plug (for the front vane) on the bottom side has a bad o-ring and is taking air. If he cleans the bottom really well by reaching under he can then put a clean white cloth and see if there is any drip. Another option would be to have the car in the air and if you can get eyes on that lower x-plug (might be impossible given its position) you could check for bubbles w/ a solution.

I've now built several of these and my consensus is that the x-plugs cause the most visibe/audible evidence for issues and troubleshooting. The front shaft seal can leak but won't cause the pump to make noises.

[Rikki Kitto]

Mine sounded like a sewing for years still worked OK though

[willg54]

Well it failed the mot due to the pump. It started knocking its **** off on the ramps.

Definitely feels like starvation to me, the original oil cooler pipe is on still. Its on its 2nd new pump so I'm thinking it's not the pump unless it's a string of bad luck.

Comes back in a trailer soon so I'll start ripping in to it!

[Rikki Kitto]

Seems like a harsh fail unless it's leaking thought it would be advisory

[willg54]

Seems like a harsh fail unless it's leaking thought it would be advisory

That's what i thought...but this is the guy who gets my TVR through so must have been bad to not pass!