Repressurising The Hydraulics

[robmc52]

Evening all

A slight problem has occured with my 2.1td that has left me a bit confused. After replacing the reversing light switch the other day the stop warning lamp comes on when the engine is started together with a no hydraulic pressure message on the display. Now I moved the LHM tank out of the way to get to the reverse switch but didn't disconnect any of the pipework, just moved it towards the engine. I gave the garage a call today and they talked me through priming the pump to remove any possible airlocks. I've had a go this afternoon but with no success, with the engine running and the bolt on the pressure valve undone I've run Lhm into the feed pipe until it's filled the tank to the brim but the warning lamps stay on. Initially there were air bubbles coming back into the funnel I was using to pour the fluid in but after a minute it settled down and I kept topping it up until the tank became full.

I'm a bit stumped now, have I done something wrong? It's very frustrating, the car was running fine before I touched it and the reverse lamps still are'nt working!

cheers
Bob

[noz]

Hi Bob,

Trying to pick my way through your description of the symtoms it sounds to me like you correctly diagnosed the problem and have actually solved it without knowing.

I take it you disconnected the rubber hose which goes from the tank to the inlet of the pump on the pump body? Then you stuck a funnel in it at the tank end and poured LHM in whilst the engine was running? The bleed screw (12mm A/F) on the regulator was slackened by approx 1 turn at this point so the pump pumped the LHM from the funnel, through the pump and back up the return pipe to the tank? In which case the funnel level decreased and the tank level increased to 'the brim' and you stopped? During this time the warning light on the dash never went out?

If so, then you probably solved an airlock problem. However, to make the light go out you have to close the bleed screw on the regulator so that the efforts of the pump go to produce pressure in the system rather than pumping the fluid back to the tank.

Sorry if I've misinterpreted your description and got it wrong but thats what I thought you meant.

If I got it wrong please describe your problem again and we'll see what we can do to fix it. It will be a very simple problem to solve.

Cheers

noz

[robmc52]

Hi Noz

From the conversation I had earlier today with the garage my instructions were to have an assistant (daughter number 2) sit in the car and start the engine while I kept a flow of LHM going into the feed pipe. At some point the warning light would go out, this would be the signal for number 2 to stop the engine and for me to replace the feed pipe onto it's spigot whilst trying to keep it full of fluid. After this was done I would then tighten the bleed screw

Well, it didn't quite happen like that, I kept tipping it in and and the tank was filling up and Lucy only turned the engine off when I told her to. From your description, which you have not misinterpreted by the way, it would seem my instructions weren't quite in the right sequence.

It's nearly 9pm now, pitch black outside, the torch batteries are dead and I've just put the boiler suit in the washing machine. Obviously I've got to go and tighten the bleed screw now just to see what happens!

Many thanks for your reply by the way, I'll report back shortly.

Bob

[robmc52]

Hi Noz

Just one question if you don't mind, should the bleed screw be closed while the engine is running as the tank is filling up or once the feed pipe has been replaced?

cheers
Bob

[noz]

Hi Bob,

With the bleed screw open, the engine running and the funnel level decreasing you can be sure that you have solved the original airlock. Turn the engine off when the funnel is just empty. Reconnect the hose to the top of the tank. Leave the bleed screw open. Start the engine and wait approx 60s. During this time the very small air bubble which is inevitable in the pipe will work its way through the pump and back to the tank. Tighten the bleed screw with (or without) engine running. The pump should now (with engine running) produce pressure and the light on the dash should go out.

Cheers

noz

ps
sounds like the previous instructions just weren't detailed enough at the right bits to prove successful.

This post has been edited by noz on October 08, 2007 11:02 pm

[robmc52]

Hi Noz

Tried it again using the sequence you describe, the warning lamp did not go out. After running the engine for a minute I stopped it and filled the feed pipe again. On the restart a few bubbles appeared so I topped it up till they went, stopped the engine again and replaced the pipe. On the 2nd restart, tightened the bleed screw and within a few seconds the warning lamp went out for about a minute, then came on intermittantly for another minute then stayed on permanently. I then left the engine running and loosened/tightened the bleed screw which resulted in rising fluid level and air bubbles in the tank when loose. I repeated this for about 20 minutes, the bubbles looked like they were coming out of the return pipe nearest the passenger side. All the time the warning lamp stayed on. I had run out of light by then but a last glimpse in the tank revealed it was full of bubbles this time with the bleed screw tight. This hadn't happened all the time I had been opening and closing the screw before. At this point the engine had been running for about 40 minutes, the pump was slightly warm to the touch. That's all I can think of at the moment, hopefully there may be a clue somewhere there to what the problem may be.

cheers
Bob

[DerekW]

Hi Bob,

I'm probably wrong here (again!) but I seem to recall that there's a sealing ball inside the bleed screw and that if you undo the screw by much more than one turn, the ball can become displaced. If that has happened then all the tightening in the world won't seal it and you will never get a pressure build up.

Apologies in advance if this is duff information.

Derek

[robmc52]

Hi Derek

I've been very careful not to loosen the bleed screw too much having seen it mentioned on other threads. I thought I'd found the problem earlier, I pulled the feed pipe off the pump and it split almost completely in half. The rubber is rock hard for about 6 inches so I cut it back and bodged on a replacement piece. Unfortunately it's made no difference to the problem, in fact now when I try loosening/tightening the bleed screw the fluid level stays constant, no bubbles coming up and the warning light stays on. I'll be ringing the breakdown people tomorrow by the look of it and letting the garage sort it out.

cheers
Bob

[dean]

Hi Bob

It does sound like the pumps feed pipe is air locked, It has to be because you haven't touched anything other than the reservoir. when i had got the hang of bleeding mine it could still take me 2 or 3 attempts to get it to work. In the end my pipe broke as well, so after seeing what a cit dealer charged for a replacement, i made my own. I got some pipe from a commercial hydraulics specialist for around ten quid and re routed it across the top of the engine. Now i can bleed the air out first time every time. There is a picture of the new pipe in the hydraulic section under 'ride height', a couple of pages in, Don't know how to set up a link to it though.
Good luck, hope you get it sorted...........cheaply

[Peter.N.]

It could be that your pump intake pipe is leaking and letting air in. Check particularly the bend where it goes into the pump and also that the hose clip is tight. Bend the pipe and check for any cracks.

Peter.N.

[UFO]

Having never actually seen under the bonnet of a 2.1 it is a bit tricky to analyse, but I think the advice re new pickup pipe is on track. You can partly prime the new pipe by putting a funnel in the tank end and pouring some LHM into the pipe then connecting it to the tank output.

I know at a tech day a few years ago it took an age of a time for BX16v to finally prime itself and lift it's belly off the ground. It had about 6 "experts" under the bonnet too!

[robmc52]

Evening all

I think you are all on the right track with the feed pipe as the culprit. The car was recovered to the garage on Friday and Phil tried to bleed it without success. He noticed a jubilee clip on it where it disappears round the end of the engine which he thought shouldn't be there, indicating thatit may have split and been repaired in the past. As I mentioned earlier the pipe felt rock hard where it goes onto the pump so it may well be the same elsewhere. I'll find out this week sometime when it's been examined more closely.

cheers
Bob

[robmc52]

Latest news on the car is that the garage has replaced the feed pipe, pump, pressure regulator, flow valve and accumulator. There is now no warning lamp but the system is still not pressurising. I think the lamp going out happened after the pipe was replaced so the rest of the parts were changed to see why the car wasn't rising. Looks like you guys were right about the feed pipe letting in air, be interesting to see what else has packed up when they diagnose the fault.

cheers
Bob

[robmc52]

Evening all

Picked my XM up from the garage today, finally running properly. The problem turned out to be a crack around the spigot that the feed pipe is screwed to. Barely noticable when in the car, once out and turned over there was a great big crack underneath that meant the poor old pump didn't stand a chance of pulling any lhm out of the tank. Once they had fitted a replacement lid and reconnected the pipework the system pressurised within seconds. Deep joy now as the steering, brakes and suspension are working better than at any time since I've had the car, making me think that there was a certain amount of air getting sucked in to the system from the day I first picked it up.

cheers
Bob

[demag]

Has your wallet got that lighter than air feeling as well as the Xm?

Glad it's back on the road though.