haybaggerman Posted July 12, 2014 Share Posted July 12, 2014 Hi all The Saracen developed a leak in one of the copper pipes running along the fighting compartment wall to the right of the drivers seat, however, it only leaked when the engine was turning. I thought the system was under pressure the whole time due to the accumulators? Does this mean that when I come to change the pipe there won't be any pressure in it? Thanks Paul Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted July 12, 2014 Share Posted July 12, 2014 Hi all The Saracen developed a leak in one of the copper pipes running along the fighting compartment wall to the right of the drivers seat, however, it only leaked when the engine was turning. I thought the system was under pressure the whole time due to the accumulators? Does this mean that when I come to change the pipe there won't be any pressure in it? Thanks Paul Paul, The accumulators will ( or should) have pressure on the valve end of them but you can collapse the hydraulic pressure in the pipes by working brakes and rocking steering wheel with engine off. If you have someone handy get them remove hyd tank cap and to watch the return flow in to the filler neck, when this ceases, pressure is gone. Once done, it would be a good idea to check the accumulator pressures, unless done recently as if left low it can damage the valve. cheers Richard Quote Link to comment Share on other sites More sharing options...
FoolsHumor Posted July 12, 2014 Share Posted July 12, 2014 Hi all The Saracen developed a leak in one of the copper pipes running along the fighting compartment wall to the right of the drivers seat, however, it only leaked when the engine was turning. I thought the system was under pressure the whole time due to the accumulators? Does this mean that when I come to change the pipe there won't be any pressure in it? Thanks Paul Working from memory, I believe the system does maintain pressure if all the valve gear is tight. As I remember the manual says to pump the brake pedal a few times, with the engine off, to bleed pressure off the system and to empty the accumulators of fluid so the hydraulic level can be checked. The accumulators would still have their charge, but pistons would be bottomed out and no longer acting on the fluid. I also recall not reading the manual soon enough and topping off the hydraulic fluid with the system pressurized and the accumulators full. Later when I leaned on the brake pedal a few times, a family member passing through the shop asked what the puddle underneath was from. Before I could answer I had to ask how large it currently was, and if it was getting bigger. If someone else says this information is wrong, they are likely correct. Regards, Bob Quote Link to comment Share on other sites More sharing options...
FoolsHumor Posted July 12, 2014 Share Posted July 12, 2014 Richard, My apologies for the overlap. I was slowly 2 finger typing while you were replying. Did not look at the thread again before sending. Bob Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted July 12, 2014 Share Posted July 12, 2014 Richard, My apologies for the overlap. I was slowly 2 finger typing while you were replying. Did not look at the thread again before sending. Bob No worries Bob, I was going to reply earlier but trying to do too many things at once! cheers Richard Quote Link to comment Share on other sites More sharing options...
Hoseman Posted July 13, 2014 Share Posted July 13, 2014 No worries Bob, I was going to reply earlier but trying to do too many things at once! cheers Richard I'm a hydraulics engineer, and just a warning about accumulator. Some can hold up to 300 bar pressure, hydraulics are killer if not careful! I've seen many wounds and pinholes in hands/fingers etc through trying to find leaks in systems while someone operates the hydraulics. Please be careful,isolate accumulators where you can(some have isolation valves on the block they screw into), de-pressurise system by operating all controls while engine off. Use laytex gloves ALWAYS, hydraulic fluid rots the skin and if old oil/fluid can contain harmful chemicals through heat and contamination. If unsure, ask advice first! I am glad to help if I can. Quote Link to comment Share on other sites More sharing options...
timbo Posted July 13, 2014 Share Posted July 13, 2014 Ditto that - Jon P recently told me about a pipe bursting on a Saladin while he was looking directly at it - queue a faceful of fluid at very high pressure! Luckily Jon is a glasses wearer or the outcome could have been very much worse..not to be messed with! Quote Link to comment Share on other sites More sharing options...
Starfire Posted July 14, 2014 Share Posted July 14, 2014 The Saracen accumulators only operate at up to 90 bar or so, but you still need to be very careful as that is certainly a dangerous amount of pressure. If it is leaking only when the engine is running, it is likely that your accumulators are also shagged and not holding any pressure; with the engine off, do you have power assist on the steering and brakes? Cheers, Terry Quote Link to comment Share on other sites More sharing options...
Hoseman Posted July 14, 2014 Share Posted July 14, 2014 The Saracen accumulators only operate at up to 90 bar or so, but you still need to be very careful as that is certainly a dangerous amount of pressure. If it is leaking only when the engine is running, it is likely that your accumulators are also shagged and not holding any pressure; with the engine off, do you have power assist on the steering and brakes? Cheers, Terry Ditto above, but don't be fooled by 90 bar, that's 1300 psi, your average workshop compressor is 10bar (150psi) and when that blows off it scares the poo out of you!!! A pinhole at that pressure is plenty to burst the skin and if you get hydraulic (or any fluid) into the bloodstream the end result is amputation!!!! Seriously!!! If anything, don't shrug it off, get the hospital and don't take chances. I agree the accumulator are prob shagged as they would still provide some system pressure when the engine is off. Are they bladder or piston type? Sealed (like Citroen spheres!) Might just need -gassing, but more than likely if lost gas will need replace/refurb. Quote Link to comment Share on other sites More sharing options...
Starfire Posted July 14, 2014 Share Posted July 14, 2014 ... Are they bladder or piston type? Most Saracens run piston type accumulators, and after 60 odd years, they probably need some new seals. Mine hold gas, but not too well... Some of the really early ones (first hundred or so) had bag type accumulators, but they worked out that they were crap and got rid of them pretty quickly. Cheers, Terry Quote Link to comment Share on other sites More sharing options...
Hoseman Posted July 14, 2014 Share Posted July 14, 2014 Most Saracens run piston type accumulators, and after 60 odd years, they probably need some new seals. Mine hold gas, but not too well... Some of the really early ones (first hundred or so) had bag type accumulators, but they worked out that they were crap and got rid of them pretty quickly. Cheers, Terry Easy enough to overhaul them then. The prob is getting them gassed up again! They can't be transported by law with gas in as classified as explosive. Can't be posted either. It's finding someone with the charging kit and a nitrogen bottle to do it onsite. We get ours done at a local company and transport them in our mobile workshops as we are insured for such. Quote Link to comment Share on other sites More sharing options...
Grasshopper Posted July 14, 2014 Share Posted July 14, 2014 Those into vintage busses have similar issues with Routemaster accumulators, very few people have the re-charge equipment. The equipment for re-charging RM accumulators was a thing called an intensifier which took a compressor supply of around 120psi and boosted it up to 600psi at the other end via a pneumatic piston. They probably should have been Nitrogen filled, but any garage I ever visited or worked at used their standard air supply and had been doing so for many many years. Quote Link to comment Share on other sites More sharing options...
haybaggerman Posted July 14, 2014 Author Share Posted July 14, 2014 Wow great response, thank you all. With regards to the accumulators, I don't seem to have much help with the steering if the engine is off, but it is okay when the engine is running. The leak was a growing puddle of oil rather than a pressurised spray, and it seems to be coming from one of the pipes that run to the accumulator next to the rear seats. The pipe seems to be about 9.5mm but it has been painted many times I expect. What grade of pipe should I be looking for as a replacement? Quote Link to comment Share on other sites More sharing options...
trophy160 Posted July 14, 2014 Share Posted July 14, 2014 Just ordered myself a charging set today so I can rebuild my accumulators, having read all these horror stories I'm not sure I want to now ! Quote Link to comment Share on other sites More sharing options...
Starfire Posted July 15, 2014 Share Posted July 15, 2014 They're fine, as long as you take some care and drop the pressure off before removing them; with the engine off, work the steering and brakes until nothing is coming out of the return pipe into the tank and then bleed off the air from the Schrader valves on the pistons and unbolt them. If you need to replace any of the lines, ensure that you get proper hydraulic pipes made up that are rated to at least 1500 PSI. Cheers, Terry Quote Link to comment Share on other sites More sharing options...
timbo Posted July 15, 2014 Share Posted July 15, 2014 http://www.rm1872.org.uk/Nitrogen-Accumulator-Charger.html Obviously make sure you check the manual for the pressures for Saracen..! Quote Link to comment Share on other sites More sharing options...
trophy160 Posted July 15, 2014 Share Posted July 15, 2014 When I bought my Saracen I got a spare accumulator with it. It is clearly not new, but looks like it might be reconditioned as it has a plastic blanking plug fitted in the hydraulic end. Would it be OK to charge this up off the vehicle and to monitor if it holds pressure over time as a way of assessing it's condition, or would this not be advisable? Quote Link to comment Share on other sites More sharing options...
Starfire Posted July 15, 2014 Share Posted July 15, 2014 It's safe enough to do that way, but they aren't too hard to swap over. According to the manual, you should be checking/topping them up monthly, so I assume you have the equipment already (I must admit that I don't yet, but its on my list of things to do in the near future). Don't forget, the Saracen brakes do not have a positive failure mode like an air brake - if your engine stops or the belt to the pump lets go and you do not have functioning accumulators, you will have massively heavy steering and no brakes. It warrants to maintain them thoroughly. Cheers, Terry Quote Link to comment Share on other sites More sharing options...
trophy160 Posted July 15, 2014 Share Posted July 15, 2014 Thanks Terry, well here is the next question in fact there is a second related question. 1. When I swap out an accumulator I am braking into a hydraulic system, where do I need to bleed the system? 2. I may be needing to change brakes hoses to the wheel cylinders, what is the procedure for brake bleeding Quote Link to comment Share on other sites More sharing options...
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