Accumulator Health Testing

[bazzbazz]

Yes 1200 ohm

[Citroënbender]

The replacement pressure sensor from Monza showed near-identical outcomes with MES as compared to the old one. It was interesting to note the physical differences in their bodies; one had a 14mm hex section abutting the thread, whilst the other was 22mm.

Here's three successive pump cycle times. I measured by prising the cover off the pump relay and observing the contact leaf's movement; timing from pull-in to next pull-in.

[bazzbazz]

Yes but does the pump now reprime the system at 45 Bar and shut off at 55?

[Citroënbender]

According to the readout, the pump seems to kick in around 44 Bar and shut off just over 54.

One only gear change is almost certain to drop the pressure enough to cycle the pump.

[bazzbazz]

Ok, then that's has fixed the pressure dropping down to 36 bar and the pump not restarting, that's one problem fixed.

If the pump is running at every gear change then the accumulator is worn and not holding pressure well. A good one you will get 2 changes before the pump running, a brand new one you'll get 2-3.

Be aware, with the accumulator wearing out it also causes extra wear on the pump brushes (runs ever gear change instead of every third), AND the pump relay. I always recommend when replacing the accumulator to replace the pump relay and replace the pump/pump brushes. Otherwise I guarantee sooner or later the pump brushes will wear out and stick and your partner will be cursing and swearing your name when she is stuck in the middle of a intersection in peak hour.   

[Citroënbender]

Ah, the joys of old age; to hear her moaning my name again... 

Good point about the pump now kicking in consistently.

I'll get an accumulator ordered up today. The real plus in this, is I'll finally know the thread and be able to make an off-car testing adaptor for them using a Citroën sphere tester. With the motor, I'll check the pump motor brushes on my "bacio di legno" car and either refurb or straight swap it. Relay contacts actually look good and socket connectivity is fine; I've checked them.

[Citroënbender]

Mixed results with new accumulator. Massive increase in standing cycle time to over nine minutes; about three times the prior result. Can shift up to three times before pump starts up.

However I can still make the pump not run by loading up its duty cycle. Then it won't pressurise, and the dash offers a "Selespeed System Failure" warning, the pump refuses to run and starting is not possible. Sometimes even keying off and letting stand doesn't seem to resolve it, although bridging the pump relay initially to start, can get me around the issue.

So... I think there is a pump refurb coming up quite soon!

Edit: I did get the clutch down to 28.014mm though.

[bazzbazz]

It's most likely in need of a rebuild. As stated earlier, when the accumulator starts to fail it needs the pump to run almost every gear change to keep up the pressure, thus the pump is being continuously run all the time instead of every couple of changes, thus exacerbating the brush wear.

If the accumulator fails, the pump usually fails soon after, one leads to the other.

[Citroënbender]

Is it worth trying to undercut the commutator or would that just be wasting time?

Are the brushes 6.35x8x18mm or 8x9x22mm? I've seen both offered as fitting.

[bazzbazz]

8x6x whatever and trim to fit.

Larger brushes will work, just more filing to do.