Air in Diesel system

the fun and games never seams to stop with me! i had the sedement bowl off my fuel lift pump the other day and after replacing i bled the diesel system following the procedure in my perkins manual. i found loads of air in the system but kept bleeding it for a while and all seamed good, it ran up well afterwards.........

untill.....i went for a long drive this morning kept losing power when going round roundabouts?! i first thought my gearbox was jamming or something untill at the third last roundabout i lost revs and the engine died! i couldnt start at all so after all the bastards honking their horns ****ed off i pushed it off the road with the help of a passer by. i checked my bleed points as it was pretty clear that there was no fuel gettin to the engine and found the govener gassed up again, i didn't have a big enough spanner to crack the injector pipes (school boy error!) but after sitting for about 20mins or so and some amount of cranking the lump fired up with a cloud of white smoke. it started with really slow rev's ( sounded like a steam train pulling away, like "chuff......chuff....chuff..chuff till it speeded up to normal rev's)

it died twice on the way home again, once on a roundabout again and then when i turned off the main road. still found wee bubbles of air but nothing much. when i was bleeding it i was getting clear streams of diesel and i couldn't see any leaks. i checked the sediment bowl seal when i put it on as i had some greif with the one on my petrol engine. but surly if there was a leak in the system it would be the diesel coming out as its at pressure???

anyone have any idea how i can stop this happening again? missed my offshore survival course cos of the bastard lump breakin down! think i'l take a taxi next time

i'd just like to add that it now bangs/coughs a bit on start up but runs ok, hasn't stopped at any more roundabouts.......

What sort of Fuel Filter head do you have?

Do you have one with a return pipe right on the top held on a banjo nut?

If you do - lucky boy!

Take the banjo nut off and look inside it - it is an air bleeder, and has a small hole in it to pass LOTS of air, and when that's gone, it will pass a little fuel.

It is very common for the tiny air-bleed hole to get choked over time, and when that happens the self-bleeding ability fails.

It takes a couple of minutes to check this - I suggest you do so before you do anything else.

If you don't have this sort of fuel filter head .... sorry!
But how would we know when you didn't tell us what engine or set-up you have?

CharlesY

sorry, its a perkins 4203 engine with the self bleeding filter (no bleed nut). the filter does have the return pipe on top with the banjo nut, i'll check for blockages in the morning. i bled it originally from the hydraulic govener vent, injector pump vent and injector pump inlet then cracked two injector pipes and bled through them, ended up with clear streams of diesel. i did think a "self-bleeding" filter sounded too good to be true, hopefully its just a bit choked up and there's a bubble of air stuck in the top that a wee bit just gets dragged through when i put the foot down?? thanks for the advice

cheers CharlesY, cracked the joint on top of the filter and got a fair bit of air out before getting clean diesel. cleaned out the banjo bolt hole as well before puttin it all back together and bleedin the reset of the system again to make sure! hopefully i'll not be stoppong on anymore roundabouts!!

ta very much!

doobie said:

cheers CharlesY, cracked the joint on top of the filter and got a fair bit of air out before getting clean diesel. Cleaned out the banjo bolt hole as well before putting it all back together and bleeding the rest of the system again to make sure! Hopefully I'll not be stopping on anymore roundabouts!!

ta very much!

Click to expand...

Well done!
The idea with the self-bleeder is that it will separate air and fuel BEFORE it goes near the injection pump and causes trouble. This means the system doesn't need to be so fussy about keeping air out all the way from the tank to the filter, and it also means you can run the tank level lower before a dollop of air stops you. The little bleed hole can pass a whole lot of AIR, but only a very little diesel fuel goes back.

If you found the bleed hole in the banjo bolt was gunged-up, I think you should find that your problem is fixed now.

Everyone who has a filter like these should clean out the bleed hole once in a while.

CharlesY