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Discussion Starter #1
Hello,
I have also posted this item on other forum sites. I am hoping that someone can give me some advice regarding a problem that I am experiencing with the hydraulics on my recently acquired 1991 Bentley Eight. From day one (early December) I have needed to regularly top up the inboard reservoir with HSMO Plus. I had assumed that there were leaks on the brake cylinders which would need some attention when I had fully studied the workshop manual and when better weather permitted. The brakes seemed quite sharp and curiously there were only very small oil stains underneath two corners of the car and so I was not unduly concerned. I say curiously as I had, in total, put in three or four bottles of HSM oil and the stains combined would only seem to account for about a teacupful at the very most. I had assumed that the missing oil had dripped and had been minutely distributed over the highways and byways of Lincolnshire. Ah, would that it were so, for today I parked the car, facing downwards, on a sloping part of my driveway and discovered to my dismay, a bright green puddle amassing just behind the N/S rear wheel. This puddle was being fed by a fine trickle of oil which appeared to originate from underneath the luggage compartment. I can only imagine that the oil had pooled within the coachwork somewhere and poured out from there due to being on an incline. Upon closer inspection, I could see that the oil was coming from inside the luggage compartment from the region of what I take to be the top of the rear damper strut. There is also a green sphere and a machined metal block into which pass green pipes in the same general area. All around these components is quite oily but I cannot work out the origin of the actual leak. I wonder, have any members had a similar experience or does anyone have an opinion as to what might, or could, be the source of the leak? Thank you.

Andrew Parker
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Your problem sounds quite similar to one that was recently discussed on the RROC (US) forums.

1. Is the sphere itself tightened down? You could have a leak from
around the suspension sphere (and from the quantity of mineral oil
you describe as having used, this could be the case).

2. Clean up around the area in question with a degreaser then go for a
relatively short drive. You may be able to see which component is
leaking.

3. The tubes you describe are the mineral oil feed and return tubes. It
is not uncommon for leaks to develop where these go into the strut.
If the leak is from the return tube on the side of the strut, you can
repair this yourself. Someone far more expert in these things than I
says:
a) Clean the area thoroughly and carefully wiggle the tube out.
b) Clean the tube end and where it inserts into the strut.
c) Apply a bit of Loctite 638 around the end of the tube and
wiggle it back in.
d) Wait about 12 hours then take the car for a drive. Check
to be certain that the leak has been sealed.

Brian
 

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Discussion Starter #3
HSMO Leak

Brian

Thank you for your reply to my posting. Someone has actually posted a similar response on another forum site and if you are both correct I should be able to cure the problem myself and relatively easily (and dare I hope cheaply). I am now quite looking forward to having a go. I will keep you posted.

Regards

Andrew
 

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Ok I think the green pipes you are refering to are the small plastic pipes from the struts. These wont leak into the luggage comp'

It would be more likely that it is coming from above the struts. Being a 1991 it will have active ride and the unit above the strut that the sphere screws into is what controls the ride setting.

When the sphere are screwed in it is a bit tricky get the seal in exactly the right place. if it does not go in quite right, it could get nipped and cause a leak. (usually it would be a lot of fluid coming out very quickly due to the pressure so this is unlikely). It could be were the top of the strut seals into the unit above. There is 2 small O rings that seal the top of the strut so that could also be the culprit. check the pipes and bleed nipple on top of those units as well as the block that the pipes from this unit go down to.

Also the struts themselves can leak. If you look at the bottom of the strut were the telescopic part pertrudes it will be obvious if there is a leak.

Please let me know how you get on.

Matt.
 

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Ok I think the green pipes you are refering to are the small plastic pipes from the struts. These wont leak into the luggage comp'

It would be more likely that it is coming from above the struts. Being a 1991 it will have active ride and the unit above the strut that the sphere screws into is what controls the ride setting.

When the sphere are screwed in it is a bit tricky get the seal in exactly the right place. if it does not go in quite right, it could get nipped and cause a leak. (usually it would be a lot of fluid coming out very quickly due to the pressure so this is unlikely). It could be were the top of the strut seals into the unit above. There is 2 small O rings that seal the top of the strut so that could also be the culprit. check the pipes and bleed nipple on top of those units as well as the block that the pipes from this unit go down to.

Also the struts themselves can leak. If you look at the bottom of the strut were the telescopic part pertrudes it will be obvious if there is a leak.

Please let me know how you get on.

Matt.
 

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Discussion Starter #6
Problem Solved!

Here is an update for those who had shown an interest in my HSMO leak problem.

Prompted by the return of the better weather, but rather more urgently by the alarming increase in the rate of oil loss, I decided to ‘get out and get under’. As I had previously mentioned, due to a restricted view, I could not see the exact source of the leak. Always one for a new gadget, I decided that an endoscope would be just the ticket and it was only after buying one that I discovered that removal of the tool shelf above the fuel tank offered me an unhindered view of and easy access to the top of the damper assembly, without the need for expensive optical equipment!

The HSMO was, in fact, seeping from around the flare nut of the damper’s hydraulic feed pipe. Having tightened this nut as much as I dared, and certainly to more than the recommended 7Nm, without stemming the haemorrhaging of oil, I removed the pipe and discovered what appeared to be a slight malformation on the end of the flared joint, which I believe could have been preventing a proper seal. After some research I discovered that there are soft copper washers available that can be used to seal flare joints and which may well have cured my problem but in the event, I decided that a new pipe was the way forward and I am delighted to report that since replacing it the hydraulic system has been leak free.

My thanks to those who offered me advice and suggestions most of which prompted further research, at the very least I can say that now I do have a fairly comprehensive understanding of the Bentley’s suspension system and thanks to my unnecessary tool purchase, unrivalled views of the inside of some of the more inaccessible crevices to be found on a Bentley Eight. :)

Andrew
 

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Very informative post,thank you for passing the information on, I have a 1990 Bentley Eight and always glad of any information like your post. We all breath a sigh of relief when we can sort problems out,especially at a reasonable cost. I am at the moment having to sort out the rear drop links on my car and have sourced some good used ones at the right price. They are £200 for one new . YEUK !!. Mention the Word Bentley when looking for parts and sit down and wait for the shock eh !!.
 
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