alfaman Posted April 27, 2012 Share Posted April 27, 2012 I have a question for the experts out there. Does anyone know as to why I have to keep on bleeding the fuel filter every couple of weeks or so? Each time I use the lift pump to check for air in the filter, and keep it primed, I always have to spend a few minuites flicking the lever to remove the air that is in the filter. Is this normal? Or should the filter be full at all times? The car runs fine, even if I forget to do it for a while. It is a 200Tdi engine. There are no obvious leaks anywhere, or any indications of wetness around pipes, etc. Any clues, please. Quote Link to comment Share on other sites More sharing options...
western Posted April 27, 2012 Share Posted April 27, 2012 once bled the fuel system shouldn't need a weekly prime or at anytime, never hand primed my 200tdi after a filter change, just fit the new filter & let the engine idle for a minute or 2, job done. if you keeping getting air in the filter there must be a leak somewhere, what state are the spill pipe work hose sections in ? has the filter got the 2 'O' ring seals on top ? Quote Link to comment Share on other sites More sharing options...
alfaman Posted April 27, 2012 Author Share Posted April 27, 2012 Spill pipes are fine, replaced the whole lot a year ago and did them again the other week, pipes perished. This has been an ongoing issue for the past few years, just been liv'n with it. Yep, filter O rings are there and new, again. ??????? Quote Link to comment Share on other sites More sharing options...
Maverik Posted April 27, 2012 Share Posted April 27, 2012 sorry, i miss-understand... how do you know there is air in there if you're not having any engine problems? - i've never had much luck bleeding the air out using the pump primer lever - certainly getting the last bit of air out..., the best thing to do is start the engine up then crack the screw on top of the filter housing, - let the engine do the pumping. when a solid stream of fuel comes out (rather than bubbles) then you nip it up. make sure you've got a rag to hand for the diesel. Filters take up a heck of a lot of fuel inside the body, if it wasn't fully filled at the beging (assuming its a new ish filter) then it might take some time to get the air out of it... I remember it took me 3 attempts to bleed the air off when I changed the fuel filter the last service time, and that was as per the technique described above, even with the engine doing it, you're stood there a few minuets with bubbles before you get a nice steady stream of fuel... Mav Quote Link to comment Share on other sites More sharing options...
101sean Posted April 27, 2012 Share Posted April 27, 2012 I've come across filter heads that have gone porous on other vehicles. They are cheap from a diesel specialist. It does sound like you have a slight air leak somewhere allowing the fuel to run back, You're not removing air from the filter itself, you are shifting it out of the fuel lines via the filter head bleed screw. Does it take a lot of cranking to start, curious as to why you'd be checking for air regularly? As Western says, it's not something you should need to touch between services Quote Link to comment Share on other sites More sharing options...
unclemicky Posted April 27, 2012 Share Posted April 27, 2012 Will im certinly no expert.....the lift pump sucks fuel up from the tank through the filters and on to the injectors.some where on this line air is been sucked in . Quote Link to comment Share on other sites More sharing options...
Christophers1247 Posted April 28, 2012 Share Posted April 28, 2012 it is normal to be able to pump the primer a few times after the engine has been run most diesel engines with a primer pump are the same but it shouldnt take a few minutes more like a few seconds or 7-10 pumps max. you have to remember that there is one big air hole in the system the filler cap and there are no one way valves anywhere up to the fuel filter so what is happening when u switch off the engine is any fuel in the pickup from the tank is flowing back to the tank so when start the engine again for a few seconds u draw air up to the filter until the system effectivly bleeds itself. Quote Link to comment Share on other sites More sharing options...
Snagger Posted May 2, 2012 Share Posted May 2, 2012 Check the seal of the olive joint at the bottom end of the pipe from lift pump to filter - the vibration wears the olive and creates a leak which is initially just small enough that no fuel leaks out but air leaks in when the engine is off, allowing the fuel in the lines to drain back to the tank. Even then, though, the filter canister should stay full, any leaks only letting the filter mounting drain back to the level of the hole though the banjo bolt in the lift pump pipe top. Check the injector pipes for tightness and cracking too. Quote Link to comment Share on other sites More sharing options...
jbs Posted May 2, 2012 Share Posted May 2, 2012 sorry, i miss-understand... how do you know there is air in there if you're not having any engine problems? - i've never had much luck bleeding the air out using the pump primer lever - certainly getting the last bit of air out..., the best thing to do is start the engine up then crack the screw on top of the filter housing, - let the engine do the pumping. when a solid stream of fuel comes out (rather than bubbles) then you nip it up. make sure you've got a rag to hand for the diesel. Filters take up a heck of a lot of fuel inside the body, if it wasn't fully filled at the beging (assuming its a new ish filter) then it might take some time to get the air out of it... I remember it took me 3 attempts to bleed the air off when I changed the fuel filter the last service time, and that was as per the technique described above, even with the engine doing it, you're stood there a few minuets with bubbles before you get a nice steady stream of fuel... Mav Mav, If you filled the filter with diesel when you were to replace it then you wouldn't have to bleed the fuel system as the filter would already be full mate,I've been doing it this way for years and it works everytime HTH John Quote Link to comment Share on other sites More sharing options...
alfaman Posted May 2, 2012 Author Share Posted May 2, 2012 the best thing to do is start the engine up then crack the screw on top of the filter housing, - let the engine do the pumping. when a solid stream of fuel comes out (rather than bubbles) then you nip it up. I've tried that, but, no fuel comes out. I suppose the lift pump is not working as it should? Engine running and cracking the connections to the injectors, fuel comes out fine. Quote Link to comment Share on other sites More sharing options...
alfaman Posted May 2, 2012 Author Share Posted May 2, 2012 Does it take a lot of cranking to start, curious as to why you'd be checking for air regularly? As Western says, it's not something you should need to touch between services Nope, the car starts no diffently than normal, immediatly. Hot,cold, freezing (-20deg), normal. Quote Link to comment Share on other sites More sharing options...
western Posted May 2, 2012 Share Posted May 2, 2012 I've tried that, but, no fuel comes out. I suppose the lift pump is not working as it should? Engine running and cracking the connections to the injectors, fuel comes out fine. hand priming the lift pump only works if the internal operating lever is on the cam lobe, if it's not the hand lever doesn't do anything, I never use mine. Quote Link to comment Share on other sites More sharing options...
Maverik Posted May 3, 2012 Share Posted May 3, 2012 When you fill the filter there is always some air still in it, - which I like to bleed out for good measure. I'm still a little confused as to how you know you've got a problem?... You don't have any trouble starting the car, and it doesn;t turn over excessivly before starting... A quick test. Start your truck and totally remove the bleed screw on top of the filter housing (or pretty much screw it out till its on its last thread)., see what happens... it should let fuel strongly flow out, keep a rag to hand and get ready to screw it back down. If you're not getting fuel out the only thing I can think it being is your lift pump is on its way out... But having said that, if you're not having any issues, keep an eye on it and maybe, buy one in as a spare lift pump (I keep one on my shelf as a "critical" spare, with wheel bearings, UJ's etc.) Quote Link to comment Share on other sites More sharing options...
alfaman Posted May 3, 2012 Author Share Posted May 3, 2012 When you fill the filter there is always some air still in it, - which I like to bleed out for good measure. I'm still a little confused as to how you know you've got a problem?... You don't have any trouble starting the car, and it doesn;t turn over excessivly before starting... A quick test. Start your truck and totally remove the bleed screw on top of the filter housing (or pretty much screw it out till its on its last thread)., see what happens... it should let fuel strongly flow out, keep a rag to hand and get ready to screw it back down. If you're not getting fuel out the only thing I can think it being is your lift pump is on its way out... But having said that, if you're not having any issues, keep an eye on it and maybe, buy one in as a spare lift pump (I keep one on my shelf as a "critical" spare, with wheel bearings, UJ's etc.) As to whether there is a problem or not, that's what I'm trying to find out. Other diesel cars I've had, when you replace the filter, it only takes a few pumps to re-prime the system. This one has me confused, I replace the filter, re-prime, no problems. A few days later I check to see if I've got the filter fully filled, nope, re-prime. Check again in another few days or so, re-prime, again. I maybe wrong, but I think the fuel filter should full, plus depending on how long I go to check the filter depends on how long it takes to re-fill the filter again. The lift pump lever works fine. I'll try the running with bleed screw off later. Let you know. Ok, just tried the above, nothing comes out and the engine starts to slow down. So turned off, re-bled the filter. Guess this means the lift pump 'aint working. Ok, how come the car runs fine????? Quote Link to comment Share on other sites More sharing options...
Snagger Posted May 4, 2012 Share Posted May 4, 2012 As to whether there is a problem or not, that's what I'm trying to find out. Other diesel cars I've had, when you replace the filter, it only takes a few pumps to re-prime the system. This one has me confused, I replace the filter, re-prime, no problems. A few days later I check to see if I've got the filter fully filled, nope, re-prime. Check again in another few days or so, re-prime, again. I maybe wrong, but I think the fuel filter should full, plus depending on how long I go to check the filter depends on how long it takes to re-fill the filter again. The lift pump lever works fine. I'll try the running with bleed screw off later. Let you know. Ok, just tried the above, nothing comes out and the engine starts to slow down. So turned off, re-bled the filter. Guess this means the lift pump 'aint working. Ok, how come the car runs fine????? The injection pump will suck the fuel from the tank too if the lift pump fails, but it's not very good at it and it's also not good for the injection pump's longevity. It does sound like you have a bad lift pump which is not only failing to do its job but is also allowing air in - it'll be either a split diaphragm inside the pump or a bad joint on the feed line from the tank. Quote Link to comment Share on other sites More sharing options...
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