OCTOPUS! The Citroën BX's Biggest Nightmare?

Added: 2026-05-10

[00:00:00]We've all heard the phrase, "Oh, the octopus is a nightmare to do on one of those." But do you actually know what an octopus is? Well, you might know or you might not, but hopefully this video will help you understand what the hell everyone's talking about and why it's so feared. This little time warp is a Citroen BX Meteor owned by channel member Graeme, and it's in here for, well, it's with me for a clutch change, but it's also with me for an octopus change because you might have seen this car at Rustville with a sizable green puddle underneath it. Well, the car has decided to try and relieve itself of all the fluid that is necessary to keep it running. And so, I'm going to change the octopus in this car. And I thought, why don't I film some little bits along the way to show you what it is and what's involved and why the bloody hell I hate doing them. Octopus isn't actually the technical name for the part that we're changing today. That is the uh oil return harness or something like that.

[00:00:53]Octopus is a nickname that was given to this part by various Citroen engineers and mechanics over the years because it looks like an octopus.

[00:01:06]What is this? Well, the best thing I can do is explain to you what all different types of hose and pipe are on a car like this so you can understand what this is.

[00:01:15]There are four types of hose or pipe on one of these cars on any hydronomatic Citroen.

[00:01:24]The first type of hose to take any notice of is this one. This is the suction hose. It is the biggest, thickest rubber hose on the car and it has one job. Fluid is sucked from that tank through that hose into the highpressure pump. That's all that does.

[00:01:42]Basically, every other hose up here is a return or a vent. That down there is a metal pipe. The fluid is sucked from the reservoir through the suction hose, goes into the pump, gets spun up at high pressure, and exits in a metal pipe. A metal pipe on these cars is always a high pressure pipe, except for the one that isn't, but there's Yeah, there's one that's not. Apart from that, everyone is a high-pressure pipe. Now, that will start at the pump and make its way around the circuit. And on this car, because it has power steering, there is down there a valve called the flow distributor valve that gives flow to the power steering, priority to the power steering if it needs it, and then sends it off around the car through various valves and things like that, eventually winding up at the wheels here or the wheel, the cylinders, uh, with the spheres on. So, this is a high-pressure pipe and this is what lifts the that pipe there. That that tiny little pipe is what lifts the car off the ground.

[00:02:41]That's pretty impressive. But the suction, it goes suction pump, high pressure into metal.

[00:02:49]That's fine. The issue with the octopus is not the high pressure side. The octopus is all about the spent stuff, the stuff it doesn't need. You have a suction hose. You have a high pressure hose or high pressure pipe which comes out the pump. That is the life circuit of the car. That is the thing that the car runs off. It's very easy to oversimplify these cars a little bit.

[00:03:12]Actually, it's easy to over complicate them. But it's also easy to oversimplify them by thinking that it is just hydraulic suspension. It isn't. That's not what these cars are. It's not what those cars are. It's not what those cars are or that one. Definitely not that one. And there's one in there which you haven't talked about that one yet. But basically the hydraulic system in these cars is is a circuit. It's a circuit that can power things. It's effectively like electricity. It powers the steering, suspension, brakes in a D, a proper D, not that one, but a proper one. It would control the clutch. There are lots of different things. It's basically a purpose of a method of driving things. So, you have a circuit going around the car, a live high-pressure circuit, which is upwards of 2,000 PSI.

[00:03:59]But what happens to the fluid after it's performed its task? Well, then it enters the remaining two circuits, suction, high pressure, return, and ventilation. A service return pipe on these cars is basically a method of returning spent fluid that is no longer at pressure back to this reservoir. Now when the car when you park one of these cars up and it's up and then over time it sinks slowly that is because all that fluid is coming back through the service returns to the reservoir and there are other parts on the car things like the brake valve the steering basically once it has served its purpose with most hydraulic systems there has to be a return back to the reservoir. They're not there well apart from the brakes there aren't many dead ends although technically the suspension kind of is but it's not actually. Um, and yeah, this is that's what a lot of this is.

[00:04:51]But some of this is also ventilation.

[00:04:54]Why is there ventilation? Well, I'll show you the height correctors in a minute because that's really the key thing that this is all to do with. But basically, for every action, there has to be an equal and opposite reaction as we know because some bloke said that.

[00:05:07]And basically, if you have a if you have a piston that's moving, then there has to be a force on the other side of it that it's that it's pushing against. Say there's a cylinder and it's pushing down. and it's lifting the car off the ground, the wheel cylinder. Well, there's going to be a suction on the other side. It can't just be a vacuum.

[00:05:24]There has to be something to allow it to balance. And then likewise, if it's compressing, there has to be a balance the other way. That's a ventilation pipe. A lot of parts on this car, things like height correctors, cylinders, things like that, they have ventilation pipes. They have pipes that allow the circuits to move. And in some cases, things like the rear cylinders, they actually bleed off a little bit of fluid. You see some of these cars leaking a little bit of fluid through the ventilation. They are actually designed to do that. It's not an oil tight thing. They have compression obviously, but they're not completely oil tight. A little bit of vapor or um air passage of air and sometimes little drips of fluid going through the ventilations. If you started getting lots of fluid going through the ventilations like they're a service return, you got a problem. But that's not what this is about. But it is what those are about. Some of these are service returns and some of them are ventilation. The strut ventilation goes into the octopus there. And then this second harness which quite often gets lumped in together as one thing because all of those are apart from the suction all of those.

[00:06:31]Some of these are service returns. This one here for example, service return.

[00:06:35]Basically, what happens is if any of these perish and fail and you get holes in, then anything that's trying to return to the tank at a nice rate, say the car is sinking and fluid is trying to return back to the tank, well, it won't make it to the tank. It will go on the floor at rust of all four.

[00:06:56]Oh dear. It's been pointed out to me.

[00:06:59]This is channel member Graham's car.

[00:07:01]That's because there's a hole in this.

[00:07:02]These have to be oil tight. They have to be oiltight. These are the way of transporting the fluid from the system back to the tank so that it can be sucked out and sent back to the pump and sent back around the car to power things like the steering and suspension.

[00:07:19]So, we are now underneath the BX Meteor.

[00:07:21]I've just done the clutch and that gives you an opportunity to see all this here.

[00:07:26]This is all high pressure stuff except for this. This is a return. So, you've got your pipe coming from the pump, which is up there. That goes into the top of the flow distribution valve because the flow distribution valve or the steering is the most uh thirsty element of the hydraulic system, but it doesn't get used all the time. It only gets used when you turn the steering wheel. Otherwise, it doesn't really do anything. And then it goes into this.

[00:07:49]This is the thing that goes, you know, that's what that is. That's a pressure regulator. And then there is actually a return out of that. There's a ventilation here which is a ventilation for the back of the valve there. There's a spring in there and so on. Now up there you can see the reservoir with the bundle of pipes coming out of it. And those are pretty much everything you see there is a collection down there. So where do they go? They go down the inner wing under the engine mount around the back of there through these sheets through that bracket which that bolt there that nut is bound to shear off and then they go to various things and this is why Citroen mechanics hate them. They hate them because the access to that is shite. Basically, that's a height corrector there. So, you got one of these on the front axle and one on the back axle. Those are those are ingenious. Those are probably my favorite part of a hydraulic system. But on a BX, they're a bastard afterthought.

[00:08:58]That is the same pretty much the same height corrector that you'll see on a D, although it has slightly different pipe sizes, but that is an absolute sod on a BX. The reason it's a sod is because coming out of that height corrector there is a ventilation pipe. You can see it at the top. It's just pressed on and then there is a flow return. Now that is I believe what's split on this and that's actually been patched up before when that height corrector was stripped and cleaned by myself a little while ago. Now the problem is with this is that the pipe comes down there and then has to bend underneath to meet it. That puts stress on the rubber and that's one of the reasons they split. But not only that, the octopus has this weird block thing, which is that there, the thing that sits above the engine mount here, and it's terrible. It just doesn't line up properly at all. It's a lot easier if you take the drive shaft out. That's why I haven't put that drive shaft back in yet. That there is a collection of ventilation pipes. Um, some of it comes from here. This is to the uh near side strut. Obviously, you got the offside strut ventilation pipes. There we have ventilation pipes here from the back axle, one from the height corrector and one from um a joint uh connection from the rear cylinders. Uh there is actually a proper return here which does use I said there was one metal return pipe. It is can't see it. That one that's actually got a rubber pipe on the end of it. But basically everything on the car, this is all high-pressure stuff cuz it's metal apart from the one that isn't. Everything on the car bundles together into one of them pretty much. And because of that, it's an absolute to change. It's not the same on other Citroen. On other Citroen, they all have the return. The Hydro Citroen all have to have those returns or the LHM ones. There is an LHM tank on a D and that has loads of return pipes going to the bottom of it but easy to get to.

[00:11:01]This is what's left of a Zantia Activiver. And well, this is kind of the same. Um, these are all returns and ventilation. Don't get me wrong, this thing will be a nightmare down there, but these are better designed than the BX1. Oh, dear. I've moved something and there's leaks.

[00:11:22]These are better designed than the BX ones. It's not an afterthought to get it into the height corrector, which is the same height corrector on here as it is on our dear friend, the BX. In fact, this one's actually got two cuz it's an axilla. So, it's just the BX that has the octopus. And it's just basically their way of trying to trying to simplify it really. They're trying to bundle all the hoses and pipes together into one rubber harness that takes everything back to the reservoir.

[00:11:50]And in theory, that's a good idea, but in practice, that's crap. And people hate changing them because minimum it's drive shaft out. If you get 1400 with a TEU, that's the easiest one to sort out.

[00:12:02]Even a 1600 like this is a dick. And I'm not going to film myself changing this because a you won't be able to see much, and b I can't broadcast the words I'm going to say. But if you get a turbo diesel or a 16 valve, honestly, some people take the engine out. Like some people actually think, you know what, I'm it will take longer to take the engine out, but it's less stressful.

[00:12:24]So now what I'm going to do is the octopus, both the return hoses on this car. Technically, one of them is the octopus, but they both count as the octopus basically. And we'll see how long it takes. But the book time is about 3 to four hours to do both of those.

[00:12:43]Time lapse I think for this one.

[00:13:18]Is this love just a bad memory?

[00:13:33]when you came around. You came around.

[00:13:37]You came around. I let you know.

[00:13:40]>> Okay. So, 50 minutes have passed and I have replaced the octopus.

[00:13:48]That's not the full story. I've replaced technically the octopus, but the important bit is this.

[00:13:59]If your BX is leaking LHM all over the floor, as this one was, the chances are it's not the octopus, it's this. If the octopus is leaking, you'll get the odd drip. If this is leaking, you'll get puddles. Now, these two little ones here, start off up here, and work their way down with the octopus to the height correctors. These are the operational returns for the height correctors, front and rear. These have a lot of fluid going through them. Uh if you're going over bumps, these will have fluid going through them. If you switch the car off and you walk away and it starts to sink, they'll have fluid going through them.

[00:14:33]And if they leak, if they've got holes in, you'll have puddles on the floor.

[00:14:37]The octopus is really just ventilation.

[00:14:39]It's the ventilation pipes. It will drip fluid if they've got holes, but it won't be huge amounts. So, if you've got a big puddle under your car, that's actually the bit you need. But to be honest, you just do them both. So, what we have there is an octopus that has been cut up. And you don't need to uh accuse me of animal cruelty. This is deliberate and that's not a real octopus. That is a piece of rubber. The reason they've all been cut up is because I cut the bottom off as it approached the octopus and then connected the new part to it and pulled it up through using a little joiner pipe so that I got it onto the right hole up here. Now you're probably thinking if you are like keeping up with this, why does it matter? Surely if they're all going back to the reservoir, what you know, underneath this port here, it all goes to the same place, doesn't it? It all goes to make a turd, as they say. Well, yeah, that's true.

[00:15:31]But if you know which of these came from where, and if you put them to the right place on here, you will know that, it makes it easier to diagnose if there are any problems in the future. If the front struts are leaking, for example, if there's a lot of fluid coming back through these pipes, you know that your front struts are leaking internally.

[00:15:50]It's good for diagnostics.

[00:15:52]If you don't know where these pipes are coming from, but you one of them is gushing fluid out, great. You know you've got a problem, but you don't know where. So, you have to get under the car. By having them come up and go to a specific place, you'll know where they've come from, and it makes diagnosing it easier. Uh, all that said, this one here has a ball bearing underneath it, which I'm guessing acts as some kind of like non- returnturn valve. So, these ones can go both ways.

[00:16:21]This one can't. It can just expel, but it can't take it back again. Um, or might even be the other way around.

[00:16:28]Anyway, I haven't even thought about that. Um, the bit I need to do next is this one. So, I've done those three there. There's this one here. We're not doing this one today.

[00:16:38]That one there is actually the brake dosa return. Uh, but this one here is the one that will make a mess on the floor if it leaks.

[00:16:46]And that's what's happening on this car.

[00:16:48]One of these pipes here goes down to the front height corrector and is leaking out everywhere. Now, with those pipes there, it's not critical that I get them back up the way that these ones came up and put them onto certain spiggots because there's only one place they can go on. And there's no way of diagnosing with them really because they are a high flow return. There's always going to be fluid coming back from there. I mean, I suppose if there was no fluid coming back from there, that would be a problem. So, what I need to do now is uh connect this up. Take this one off. Plug this one in. These go to the height correctors, as I say, front and back.

[00:17:21]And this end here, this is the flow distributor valve return. And that one goes under the car. Um, these are high flow. If these leak, we get a puddle. So hopefully they won't because then he'll bring the car back to me and he'll be upset. These are the height corrector returns. Now this is nine times out of 10. If you've got a big puddle under this side here on a BX on the right hand side of the subframe, it's coming from that.

[00:17:50]get my finger in there. Wow, that's zoomed in. That there, that spigot.

[00:17:54]You'll notice there are two in there.

[00:17:56]You would if my phone wasn't trying to zoom uh focus on things that were closer to it. Um yeah, the access is about as good as you can imagine. Hang on. Does that help it?

[00:18:09]There we go. So, uh at the top there, I can't get my finger to it.

[00:18:16]That one is the vent.

[00:18:19]That is not a high flow circuit at all.

[00:18:22]It's just vapor. But that metal spigot there, the one that comes off at an angle and then makes the hose have to immediately kink up on itself, that is the return for the height corrector. The return for the rear height corrector is the one that connects to I said it was that one earlier. It's not. It's I've disconnected it now, but there is a metal pipe in there.

[00:18:45]There it is.

[00:18:48]See it in there?

[00:18:49]And that's one of those along there. Um, so that is the uh return from that thing up there. But progress being made. If you got a leak on that side, it's probably what it is. around and let you know. And when you were down, when you were down, when you were down, I made you home.

[00:19:23]Just a bad memory.

[00:19:31]If you come around, you come around. You come around, I'll let you know. When you were down, when you were down, when you were down, I made you.

[00:20:07]Well, it's a little while later. I'd say I'm done. Uh, I've done the clutch and the octopus, both bits. Um, there is actually a third bit, the bit that goes to the brake dozer valve. That is technically, well, I don't know if people would count that as part of the octopus, but really octopus is just a nickname given to a return harness. It is rubber return pipes with all the suspension, braking, and steering fluid in it, which is the same fluid obviously. So, all that remains now is for me to fire this thing up and see if it can lift itself off the ground without spraying fluid everywhere. I would prefer that it does. Right, stage one, carburetor.

[00:20:49]Carburetor doing what carburetors do.

[00:20:58]being rubbish.

[00:21:18]Right. So, we're not going to hear any that's hissing a tick noise um with this thing yet because the uh bleed valve, which is there's a valve on the pressure regulator, it's a bypass valve basically. It just means that the system doesn't allow itself to charge up. It just lets it go back to the tank without charging everything. Um that's open at the moment. You normally only open that if you're um trying to bleed the system in from scratch. Well, this isn't from scratch. It's got quite a bit in it, so it doesn't really need it. When I crack that uh bolt up, it's only undone quarter of a turn. So, when I do that up, it should just immediately start hissing and ticking. And if I've done it right, it will lift off the deck. At the moment, it's on the ramp and I wouldn't be able to get it off.

[00:22:19]You hear that change?

[00:22:50]These cars never get boring when you turn that screw and they start lifting and hissing. in and you know picking themselves off the deck. It's like they've got a personality like a character.

[00:23:02]That one better have a good one. If I find any leaks under that thing, I don't care if it's a customer's car. It gets burned.

[00:23:27]Looks lovely out there, doesn't it?

[00:23:34]Give it 15 miles. That'll be wet and look like Right, the next test.

[00:23:51]take the pressure back out of it and then drop it on the deck. See if that height corrector leaks.

[00:24:04]Right. Well, I'm going home to test drive this car. Take it home tonight.

[00:24:08]Make sure the clutch is working. Okay.

[00:24:09]Uh that was the bigger job. 6 hours all told. 6 hours to do clutch and both those parts of the octopus. I'm quite happy with that. Um, no aquatic life was harmed in the making of this video, by the way. Don't get pa on me. And, um, yeah, I'll see you another time when I'm working on something else, probably.