Bleeding awful.

[gazdavan]

I have a strange fault on my 300tdi, XS.
After starting, runs for 20 secs. as you pull off loses all power. Full throttle twice and it returns. this is with the bleed nipple on the fule filter cracked slightly. With it closed and bled, the engine will die away and will not restart. cracked slightly, and after the religious full throttle thingy, will then run all day long - went from South wales to cornwall and back (500 miles-ish) with out a sniffle!

Any ideas where the air is getting in? After I bought it, I was told that the last owner was a ' tinkerer' and may have played with the fuel delivery, but i thought that was preset on the 300tdi?

Any advice will be most welcomed


gaz

[Swingletree]

You might find that there is a crack in the bleed screw that only opens up when it is screwed up tight. The bleed screw seems to be the only thing that is affecting the running so give it a thorough checking out. You could also check all the fuel lines and joins for airtight seals and the filter and sedimenter for the rubber seals being seated ok. ;)

[gazdavan]

Thanks for the advice. I stripped down the fuel filter housing, to check whether the seals were leaking, but all seemed ok. the copper washer on the nipple is a little worn, but not excessive. After it all goes back together, the engine does start better, and runs a lot smoother so did some good, but the symptom is still there, 20 secs of running, then all dies away with low revs ( sometimes stalls) then after a few seconds at full throttle power returns...with the bleed nipple cracked slighty. runs fine for duration as long as nipple is cracked -returns only when left standing for 4 hours or more.

next task is to check lift pump, incase that is at fault. . .

[ahebron]

Can't help but welcome to the weird and wonderful world of Discovery:D

[oops]

Have you tryed a new filter? The old one could be blocked.

[rbm]

are the sedimentor seals new, if not renew them. fuel filter how old cheapy or good make? if lift pump fails and won't lift fuel or cam lobe is worn then the engine will still start and run after a long crank as the injector pump will pull fuel through.

if you lift pump has the prime lever on the side - pump it up first thing and then try.

[gazdavan]

The fuel filter is relativley new - changed by last owner about 2 months ago and no brand name on the side of it. Havent done anything to the sedimentor yet. and dont know if it has been changed.

I did the priming thingy, after taking the fuel filter apart, primed and primed but didnt seem to get anywhere. Switched on the ignition to energise the stop solenoid, and according to the haynes manual, should get some resistance, but didnt get anything. Cranked the engine and primed it that way. thats why I think it may be the lift pump, maybe a small tear in the diaphram, which cannot hold pressure.

In normal use, always starts within 2 revolutions, no probs there, then 20 secs later dies away . . . you knw the rest.

But hey! nie to see some response from other disco people....thanks so much

[TEMPL4R]

If the diaphragm is split, it dumps fuel in the sump, check the oil level, it will be rising and thin.

If there is no resistance, the arm is on the cam, turn the engine up to a full turn and it will be on the back of the cam and at full stroke.

Does the injector leak off pipe go to the filter head or join the return to the tank?
If the previous owner was a tinkerer ( AKA a PITA) he may have "modified" his system.

Chris

[gazdavan]

Hmmm. Yes he was a bit of a tinkerer - (PITA?) and did say he had ' played with the pump' on my last conversation with him - which pump, lift or injection is not known. . . but will have a look at that, thanks

[gazdavan]

Oh, ps - I changed the oil not long after purchase, it was thick and black, and low level, so probably not the diaphram then. - much like all the other oils in the running gear....

[gazdavan]

OK. Stardate 170608. After another ' chat ' with the last owner, I found out that he had 'tweaked' the fuel screw on the pump ( smoke screw ) by ramping it all the way in and after then finding that he had problems wound it all the way back out.
I have had a little play with it and the engine sounds much sweeter. The problem with the bleed screw is still there, but now when i lock the bleed screw closed it takes about 40 seconds bfore any change happens, and the its a gradual slowing of idle speed, bit like when a petrol engine is stuck on choke. Can you choke a diesel?

In answer to a earlier question. The leak off pipe goes to a banjo fitting at the back of the pump and then off to the tank.

Pics on the way soon . . .

If anyone is still interested, will be grateful for any advice / help. . .Still cannot understand why the bleed screw needs to be cracked open for it to run.
Thanks for all the replies so far. I am getting a better insight into my disco baby..!

[littlelegs]

It would appear to me that you first need to replace the bleed washer. If it is not sealing properly, and overtightening or a hardened copper washer can do this, it will easily draw air in when stopped. Once running any air getting in will be returned back to the tank with little effect but if stopped for any time it will enter the leak and build up in the filter top as the fuel can run back through a leaky pump valve. When you start again this accumulated air gets into the injector pump and injectors as one big lump slowing the engine until it has all cleared. Cracking the vent may actually be helping to vent or might just be coincidental to the air clearing. I would also change the fuel filter in case the seal is leaking, fill with diesel before fitting and check the pipe connections for tightness. The other reasons for air accumulating are the tank connections and pick up pipe which rust and become porous and a weak or slightly porous pump diaphram that may only draw air without passing fuel.

[gazdavan]

Thanks for you help. I just changed the fuel filter as suggested, but after filling with diesel and attempting to bleed, found that I couldnt with the priming lever, although it moved through its full range, and i turned the engine to ensure it was not on its cam. I cranked it to prme it that way and after starting ran great. But no fuel ever seems to purge from the bleed screw. Eve with it fully removed when running -maybe a faulty lift pump as you say.?

I unscrewed the fittings to the filter head, found the outlet had one extra copper washer which i removed. nothing wrong there. Reattached, and fired first time. As soon as the bleed screw is closed, and a wait of 40 60 seconds, then the engine begins to die. Will not restart until that blee screw is opened again....

So change of lift pump next then....
Thanks again - It is now frying my brain, I know a lot about petrols but diesel is all new to me, only know the basics - but this is giving me Special High Intensive Training! haha

[littlelegs]

Thanks for you help. I just changed the fuel filter as suggested, but after filling with diesel and attempting to bleed, found that I couldnt with the priming lever, although it moved through its full range, and i turned the engine to ensure it was not on its cam. I cranked it to prme it that way and after starting ran great. But no fuel ever seems to purge from the bleed screw. Eve with it fully removed when running -maybe a faulty lift pump as you say.?

I unscrewed the fittings to the filter head, found the outlet had one extra copper washer which i removed. nothing wrong there. Reattached, and fired first time. As soon as the bleed screw is closed, and a wait of 40 60 seconds, then the engine begins to die. Will not restart until that blee screw is opened again....

So change of lift pump next then....
Thanks again - It is now frying my brain, I know a lot about petrols but diesel is all new to me, only know the basics - but this is giving me Special High Intensive Training! haha

You should be able to pump fuel out of the vent so a new pump then. Come to think of it I had a similar problem after changing the filter and had to fit a new pump, seems it will keep going until disturbed. Probably the pump is only supplying just sufficient head to work but not enough to push it out the vent and when you open it it does help it along.

[gazdavan]

Been a busy week, as i had to go to cornwall. On the way down, 40 miles from my destination, the water temp went through the roof. One of the black plastic bungs on the thermostat had burst. After a long wait for the RAC, the RAC man was a landy fanatic ( 110 owner ) and went and got me some new brass replacements from his mate at the main dealers - fiver for 2

the upshot is that I have a leak in the head gasket between a piston and the water gallery which is over-pressurising the cooling system.:eek:

No garage in cornwall would touch it, so with prayer and a big packed lunch, limped home the some 175 miles back to wales. 45mph all the way - keeping the engine under 2000 revs. lots of stops for water top ups

repacement heads seem to be like rocking horse poo but finaly got one in swansea for 200 notes. . . . new thread methinks...:rolleyes:. thanks for all your help on this matter.:D

Cheers

gaz

[littlelegs]

Been a busy week, as i had to go to cornwall. On the way down, 40 miles from my destination, the water temp went through the roof. One of the black plastic bungs on the thermostat had burst. After a long wait for the RAC, the RAC man was a landy fanatic ( 110 owner ) and went and got me some new brass replacements from his mate at the main dealers - fiver for 2

the upshot is that I have a leak in the head gasket between a piston and the water gallery which is over-pressurising the cooling system.:eek:

No garage in cornwall would touch it, so with prayer and a big packed lunch, limped home the some 175 miles back to wales. 45mph all the way - keeping the engine under 2000 revs. lots of stops for water top ups

repacement heads seem to be like rocking horse poo but finaly got one in swansea for 200 notes. . . . new thread methinks...:rolleyes:. thanks for all your help on this matter.:D

Cheers

gaz

Sorry to hear that, are you sure you needed a new head and not just a gasket or skim? You can fit 1/2" radiator vent or blank plugs, same thread and might be worth doing the rad vent as well!