can you run engine with pressure relief screw undone ?

BX Tech talk
Kitch
Over 2k
Posts: 6417
Joined: Sun Jul 03, 2005 9:36 pm
Location: Fareham, Hants
My Cars: Too many to list
x 88
Contact:

Re: can you run engine with pressure relief screw undone ?

Post by Kitch »

BX Meteor wrote:I've got a leak in the rear suspension above the rear exhaust box and I want to turn the car around to be able to work on the back more easily.

LHM pisses out even on low suspension, so can I undo the pressure relief screw and move it like that ??

If not then I'll have to take off the pump belt ffs.
Sorry I think I've misunderstood this? I've read people saying you can't do this - you could. If you crack the pressure relief screw, all that will happen is the PR will go open circuit, the system won't pressurise and the car won't rise. It'll slow any leak you have right down (though it may not stop it).

Unless it's a massive return hose, it's not going to leak with no system pressure behind it. The issue is whether you could move it around on low without beaching it!
One third of a three-spoke BX columnist team for the Citroenian magazine.

CCC BX registrar: The national BX register - click to submit a car!

1983(A) 16TRS (Rouge Valleunga)
1990(H) 16Valve (Rouge Furio)
User avatar
MULLEY
Over 2k
Posts: 8406
Joined: Thu Jun 22, 2006 11:10 pm
Location: Derbyshire
My Cars: 1999 Xsara LX 2.0HDI (90) Hatch - Fern
2002 C5 2.0 HDI (110) Estate - Jasmine - SORN
2011 Mini Cooper D Clubman - SOLD
2016 Mercedes A180D Sport - Auto refinement
1992 TZD Turbo - Bluebell - SORN
1992 TZD Turbo Estate - SORN
1991 Gti 16V - Blaze - crash damaged, will get repaired - SORN
1990 Gti 8Valve SOLD - looks like it's been scrapped
2002 Mini Cooper S - SOLD - i miss this car
1992 TXD - Scrapped in March 2014
1988 CX 25 GTI Turbo2 - SORN
1996 - AX Memphis 1.5D - Dream - SORN
x 8

Post by MULLEY »

How much pressure is coming from that leaking pipe? Could you not rig up a pipe to flow back into the lhm tank as a temporary measure rather than it all pissing away onto the floor?
2002 C5 2.0 HDI Estate - Jasmine - Now SORN
2011 Mini Cooper D Clubman - SOLD
2016 Mercedes A180D Sport - Auto refinement
1992 TZD Turbo - Bluebell - My daily
1991 Gti 16V - Blaze - crash damaged, will get repaired.
1990 Gti 8Valve SOLD - looks like it's been scrapped
2002 Mini Cooper S - SOLD - i miss this car
1992 TXD - Scrapped in March 2014
1988 CX 25 GTI Turbo2 - SORN
1996 - AX Memphis 1.5D - Dream - SORN

I'm not just a username, i'm also called Matthew.
User avatar
BX Meteor
BXpert
Posts: 985
Joined: Thu Mar 31, 2011 9:04 pm

Re: can you run engine with pressure relief screw undone ?

Post by BX Meteor »

Kitch wrote:
BX Meteor wrote:I've got a leak in the rear suspension above the rear exhaust box and I want to turn the car around to be able to work on the back more easily.

LHM pisses out even on low suspension, so can I undo the pressure relief screw and move it like that ??

If not then I'll have to take off the pump belt ffs.
Sorry I think I've misunderstood this? I've read people saying you can't do this - you could. If you crack the pressure relief screw, all that will happen is the PR will go open circuit, the system won't pressurise and the car won't rise. It'll slow any leak you have right down (though it may not stop it).

Unless it's a massive return hose, it's not going to leak with no system pressure behind it. The issue is whether you could move it around on low without beaching it!
Intersting point you make there about moving the car with a leak, it might have been a bit easier. My car did move OK with pump belt slackened (because I fitted the exhaust and it's all tucked up nicely), just a tiny scrape on a slope out, and back in.
MULLEY wrote:How much pressure is coming from that leaking pipe? Could you not rig up a pipe to flow back into the lhm tank as a temporary measure rather than it all pissing away onto the floor?
I'm not even totally sure where it's coming from (look at the video). I'll try kitch's suggestion and crack open the pressure relief srcew to see the leak better.

I don't need the car btw so I'm going to repair it properly (when I've found the leak, if I can undo the union).
bx petrol auto saloon
BXpert
Posts: 477
Joined: Mon Aug 22, 2011 11:50 am
Location: Tonbridge KENT
My Cars: Citroens SAABs and Vauxhalls
x 2

can you run engine with pressure relief screw undone

Post by bx petrol auto saloon »

Dear Mr Meteor.
You have done really brilliantly so far Brian. they do p**s out I am
affraid :roll:
Have you looked at the price and availabilty of a height correcter
and new associated pipes, from Pleiades or chevronics maybe, as yet
Brian :?:
The other option if one brake pipe union snaps, is to remove the
height correcter and drill out the broken union, carefully and straight
and peel the threads out with a pair of long nosed mole grips/pliers.
Hope this helps Brian :wink:
Well Done so far Brian.
Vince.
Passion Hydropneumatic Citroen,s

Cars;- 1993 White Citroen BX 1.6 TXi petrol
saloon auto with air-con & ABS.
47,594 Miles from new.
Owned for 3 years sorned.
1988 Silver SAAB 900i 2.0 8v F/lift,
saloon 5sp with 3 spoke Ronals,
69,000 Miles from new.
Owned for 15 years T & T.
User avatar
BX Meteor
BXpert
Posts: 985
Joined: Thu Mar 31, 2011 9:04 pm

Post by BX Meteor »

Hi Vince
Many thanks for the encouragement
The problem is going to be getting the offending union undone "in situ". [-o<
In a utopian world, all unions on all BX's will come undone. Thus when a pipe starts to leak in Utopia, it is easy to remove and replace. \:D/
But the unions (like the brake bleed nipples) are made of cheap French cheese. #-o
When one union cannot be undone, one can hope that the remaining unions can be undone, then the HC removed to undo the remaining union in a vice. 8-[
However, if no unions can be undone, then all pipes need to be cut, then the unions removed in a vice, then new pipes fitted all round. :roll:
Alternatively, if there is enough pipe remaining, leave all the unions alone and fit a homebrew piece where the leak is (mentioned in this forum) :idea:
i.e. cut back the pipe, fit female parts and flare the pipe ends, then fit a piece in the gap (mind the gap)
I'm a perfectionist though, so I'd even go the full way of replacing all pipes if necessary. :-k
Or scrap the car as it's a waste of my energy doing that ~titanic~

Tomorrow I'll try Kitch's suggestion and start the car with the pressure screw cracked opn and see where the leak is exactly.
Should be an update tomorrow.
cheers, Brian
Mickey taker
Over 2k
Posts: 3209
Joined: Wed Apr 01, 2009 10:38 pm
Location: M K
x 1

Post by Mickey taker »

keep the faith Brian
1991 BX Meteor 1.6

light travels faster than sound, thats why you look intelligent and then you spoil it all by opening your mouth !!!!!
Kitch
Over 2k
Posts: 6417
Joined: Sun Jul 03, 2005 9:36 pm
Location: Fareham, Hants
My Cars: Too many to list
x 88
Contact:

Post by Kitch »

Don't wind it all the way out, otherwise the ball bearing will pop out. Just crack it half a turn with the engine off. You'll hear it hiss and then stop, but nothing will leak out. It's not an external vent, it's internal. It just allows fluid to bypass the PR essentially (it's a bit more complex than that, but that's it in a nutshell!)
One third of a three-spoke BX columnist team for the Citroenian magazine.

CCC BX registrar: The national BX register - click to submit a car!

1983(A) 16TRS (Rouge Valleunga)
1990(H) 16Valve (Rouge Furio)
citronut
Over 2k
Posts: 2781
Joined: Wed Oct 31, 2007 7:55 am
Location: EAST SUSSEX UK
x 1

Post by citronut »

you dont actualy get citro blood peeing out with the bleed valve slackened,

so yes you can just do that to stop the system presureising,

and the prob fitting new front to rear pipe without dropping the sub frame , is you cant be 100% sure the pipes wont rub/shaife on anything were they go out of sight over the N/S corner of the sub frame,


regards malcolm
curent ride
K reg BX 17TD TZD est
also own
K reg D special

no longer have
H reg CX saffari 2.5 TRI (now gone to Malaysia)
R reg xantia 1.9TD est (gone to meet its maker)
Gibbo2286
BXpert
Posts: 430
Joined: Fri Jun 11, 2010 4:58 pm

Post by Gibbo2286 »

Usually the leaking pipe is over the front left hand corner of the subframe, if you can determine which one it actually is you can stop the leak by crushing the pipe flat forward of the damage, a good strong pair of mole grips might do it, or two hammers.

Once that's done you can run the engine without LHM spewing out and the car will lift enough to move around.
bx petrol auto saloon
BXpert
Posts: 477
Joined: Mon Aug 22, 2011 11:50 am
Location: Tonbridge KENT
My Cars: Citroens SAABs and Vauxhalls
x 2

Can you run the engine with the pressure relief screw undone

Post by bx petrol auto saloon »

Dear Mr Meteor.
You are a very clever chap Brian :wink: I really hope everything
goes well tomorrow too Brian :D :D Fingers crossed :)
Take Care Brian.
Vince.
Passion Hydropneumatic Citroen,s

Cars;- 1993 White Citroen BX 1.6 TXi petrol
saloon auto with air-con & ABS.
47,594 Miles from new.
Owned for 3 years sorned.
1988 Silver SAAB 900i 2.0 8v F/lift,
saloon 5sp with 3 spoke Ronals,
69,000 Miles from new.
Owned for 15 years T & T.
Mothman

Post by Mothman »

I have had to get home to to a garage in the past with a major green blood leak in the past and driven both motors 50 miles plus to do so with everything as flat as it could be and having had it fixed all ok with no other problems, so a few feet i dont think would be a problem.

Andy
User avatar
BX Meteor
BXpert
Posts: 985
Joined: Thu Mar 31, 2011 9:04 pm

Post by BX Meteor »

Hi Vince
I'm on a par with you :lol:
I've taken a couple more pics, below.
Thanks for the good wishes
cheers, Brian


I've put an arrow in this one showing where the hole is (it's at the back of the pipe where the arrow tip is, a small pin-prick sized hole)

Image



This pic shows where the pipes come round the rear subframe, the flash makes them look worse than they are. The LHM is from the spray from the hole near the HC (it gets everywhere at 2000 psi). I had already replaced one of the pipes (right at the back), that was the pipe from brake master cylinder to T-piece at the rear. It went round the subframe etc quite easily. I might replace the others as well as the one that's got the hole in it.

Image
User avatar
saintjamesy89
1K Away
Posts: 1994
Joined: Tue May 04, 2010 8:01 pm
Location: Somerset
My Cars: 1985 Citroen BX19 GT
198x Citroen BX16 TRS auto
1988 Volvo 740 2.0 GL Hearse
1991 Saab 900 16v convertible
2007 Lexus RX 400h SE
x 123

Post by saintjamesy89 »

Could you chop off the offending pipe at either side of the hole and insert a new piece of pipe, with suitable unions to the two ends?

Or is the LHM at too high a pressure here for that to work? I'm not too familiar with the suspension system - yet!
I'm not a Saint, or a James, but a Tom Saint-James!

Mes voitures:
1985 Citroen BX19 GT
1988 Volvo 740 2.0 GL Hearse
2006 Lexus RX 400h SE hybrid
User avatar
BX Meteor
BXpert
Posts: 985
Joined: Thu Mar 31, 2011 9:04 pm

Post by BX Meteor »

Yeah that's been done by several people on the forum before.

It needs a flare tool to do the job in situ, and I'm not sure that there is enough space, nor enough pipe left as the hole is very close to the Height Corrector (see arrow 2 pics previously)

Here is a pic of the pipe I replaced on the rear brake T-piece over 3 years ago. The main arrow shows where the hole was (that is now the new pipe). The smaller arrows show where I undid the unions that go to each rear caliper so that I could remove the T-piece to get the old union out of the T-piece in a vice.. You can see the new union on the T-piece, the new pipe runs all the way to the front connectors on the chassis. The point is that the long pipes can be replaced without dropping the subframe, providing you take your time and use an assistant to help (see also previous pic).

Image
User avatar
BX Meteor
BXpert
Posts: 985
Joined: Thu Mar 31, 2011 9:04 pm

Post by BX Meteor »

Grenman wrote:I have had to get home to to a garage in the past with a major green blood leak in the past and driven both motors 50 miles plus to do so with everything as flat as it could be and having had it fixed all ok with no other problems, so a few feet i dont think would be a problem.

Andy
Hi Andy, main problem was that I didn't want a trail of LHM to clean up.

To turn the car round, I have to move the car from the back of the house, down the drive, onto the road, turn it around, then drive it back up the drive, and then round the corner to the back of the house again. LHM would go everywhere :shock: If I'd known about the pressure relief screw being OK I would have done that, but instead I removed both belts. Molegrip trick suggested by Gibbo might have been another idea.

Anyway, car is there up on axle stands with a big pool of LHM (see the video). First pic above with the HC and single arrow, shows where I've located the leak. I'll see if I can get all new pipes, if I can I will cut out the HC and remove the unions in a vice (that's each union in a vice, not HC in a vice). Then pull out old pipes and fit new ones, one of my sons can assist feeding each pipe round the subframe (that's what we did with the brake pipe 3 years ago).

I've found the following for the part numbers I will need

10, & maybe 11,12,13 here

Image

2, & while I'm at it 6,7,8 here

Image

18 here

Image
Post Reply