Tired pumps

Unread post by **CitroJim** » 11 Jan 2010, 19:42

XantiaMan583 wrote: My thinking is that if the Activa sphere is weak for example, that the pump will have to work harder in some circumstances, at higher revs, less of a problem as the output of the pump may be higher. I've never noticed it with the revs high. The pump may get weak with age but if the overall pressure is correct then there may be a weak point in the system which will show up as another problem, such as the heavy steering at low revs and for the first 5 minutes of a drive (hope that makes sense?)

Yes, perfectly

The only flaw is the PAS and suspension pumps are entirely separate but do share a common supply. Now a problem obn the suspension side should not materially affect the PAS side and vice versa but if the supply side is marginal in it;s flow/volume capacity then it might as both sides are calling for a high volume/flow at the same time. A weal Activa Accumulator could cause this possibly as the Activa side is a heavy consumer of LHM volume in the same way a PAS ram is. Effectively they're similar in construction and operation.

My thought is that the pump supply is unable to flow the required volume of LHM when demand is high from both sides.

Have you ever replaced the Activa accumulator Gareth? And did we check yours Xac? Can't recall now

I never changed that one when I owned your Activa Gareth but i do know the pump was replaced shortly before I bought the car...

The Activa Accumulator needs to be an Anti-Sink sphere blown up to 62 bars...

XantiaMan · Unread post by **XantiaMan** » 11 Jan 2010, 19:49

Nope not been replaced, was dated 2006 though so not *that* old.

Its the one mounted on the NS chassis leg above the gearbox and below the air filter/battery IIRC?

Unread post by **xantia_v6** » 11 Jan 2010, 19:49

CitroJim wrote:
xantia_v6 wrote:
CitroJim wrote:The MK2 differs from the MK1 here as the operating presure for the electrovalves are indirectly derived.
Can you translate that into plain english?
hence why it seems a MK2 can suffer a hard rear for a while at first start-up whereas in the MK1 this is a rare occurrence.

Thanks for the clarification.

Unread post by **CitroJim** » 11 Jan 2010, 19:56

XantiaMan583 wrote: Its the one mounted on the NS chassis leg above the gearbox and below the air filter/battery IIRC?

Yes, that's the one Gareth...

Unread post by **xantia_v6** » 11 Jan 2010, 20:12

XantiaMan583 wrote: there may be a weak point in the system which will show up as another problem, such as the heavy steering at low revs and for the first 5 minutes of a drive (hope that makes sense?)

A slightly slipping belt might only show up at idle, where the peaks in torque required by the pump are more pronounced. Belts usually slip more when cold.

XantiaMan · Unread post by **XantiaMan** » 11 Jan 2010, 20:15

xantia_v6 wrote:
XantiaMan583 wrote: there may be a weak point in the system which will show up as another problem, such as the heavy steering at low revs and for the first 5 minutes of a drive (hope that makes sense?)
A slightly slipping belt might only show up at idle, where the peaks in torque required by the pump are more pronounced. Belts usually slip more when cold.

I would say that side of it is all well, it had a new belt recently and the tensioner is mega tight.

At some point it will have a new Activa sphere to rule it out.

Xaccers · Unread post by **Xaccers** » 11 Jan 2010, 20:16

We didn't check any of the front sphere's in the end Jim, although I believe I changed the Acc as a matter of course (will have to take a gander).
You thougth the Activa sphere was ok due to the dancing you got Juliet to do by sticking a screwdriver in her hole underneath.

XantiaMan · Unread post by **XantiaMan** » 11 Jan 2010, 20:26

The Activa dance should prove the anti roll is working correctly but without driving it at the same time may not rule out the Activa sphere completely.

Unread post by **CitroJim** » 12 Jan 2010, 06:08

I agree Gareth. It could be a bit flat and the Activa system could be drawing on the main accumulator when doing the dance test.

Xac, might be a good idea to get Martin to blow you up a new sphere and fit it, just in case...

I'm wondering if this heavy steering is another MK2 quirk. Mine never suffers from it...