Leaking pump likelyhood ?

[Dave Burns]

Simon you don't mention any oil leaks from the pump as far as I'm aware, just that you suspect air is somehow getting in, any fault in the pump body whereby air could be drawn in, will almost certainly result in oil getting out especially during engine inactivity.

By the way I think the poor ride quality is unlikely to be anything to do with air in the system, you would need a large amount to cause an effect that its entry point should be pretty easy to find, and so far you have drawn a blank.

Any air bubble that got in would be at atmospheric pressure to start with, then when it enters the pump and gets into the system, it will be at well over 1000 psi and be compressed to virtually nothing which is why there would have to be a significant amount getting in to make any difference.


Dave

[Mandrake]

Simon you don't mention any oil leaks from the pump as far as I'm aware, just that you suspect air is somehow getting in, any fault in the pump body whereby air could be drawn in, will almost certainly result in oil getting out especially during engine inactivity.

Hi Dave,

Not necessarily, depending on where the leak is and what kind of leak it is. On the 2 litre 8 valve petrol engine the pump is right at the top and actually as high as the level in the tank, so the tank can't syphon through a leak in the pump anyway.

By the way I think the poor ride quality is unlikely to be anything to do with air in the system, you would need a large amount to cause an effect that its entry point should be pretty easy to find, and so far you have drawn a blank.

Well I beg to differ with it not affecting the ride quality, its almost certainly the problem, as I've spent close to a year eliminating all other possibilities.

To give an idea of other things that have been done over the last year:

Spheres have been checked and replaced or regassed, Hydractive electrovalves have been repaired and replaced, (one each) the Hydractive computer has been closely monitored for proper operation, the front suspension strut cylinders have been replaced, the front droplinks have been checked (and one replaced) the balljoints have all been checked, the ride height is correct, the LHM has been replaced (and the system flushed) and the tyres are all new.

There isn't much else left

Despite this the ride quality is intermitantly both harsh over broken surfaces, and at the very same time bouncy and unstable. Most times thoroughly bleeding the system (Citrerobics etc) restores a good ride for a short time, lasting no longer than one day. (A few months ago the effect would last a couple of weeks or more - presumably due to less leakage back then)

By the way there is a continuous stream of small bubbles all the time now, so it doesn't take long for the amount of air to build up in the system. Just because I havn't found the precise source of the leak yet doesn't deny the fact that there is one...

The ride quality gets progressively harsher and more bouncy with good correlation with how often and how much I see bubbles circulate in the return line...

Any air bubble that got in would be at atmospheric pressure to start with, then when it enters the pump and gets into the system, it will be at well over 1000 psi and be compressed to virtually nothing which is why there would have to be a significant amount getting in to make any difference.

Thats a good point.... but also remember the suspension only operates at about half the full pressure at the front and a third at the rear under unladden conditions, so any air bubbles that built up in the housing of the pressure regulator would expand back by 2 to 3 times when they enter the suspension where the pressure is lower...

Until the leak is fixed, nobody can no for certain whether it is the cause of the ride harshness or not. (But if it isn't I've certainly drawn a blank as I have covered EVERY other possibility over the last few months...)

Regards,
Simon