19j air in fuel.

So , new engine in , all running fine, except, air in the leak off pipes, clouds of white on start up and missing.
Let it run for a minute or two, air clears, stop it , leave it , air seems to rise from the pump to the leak off.

Open the throttle and more air enters the leak off.

Now there are no leaks, thats the thing, air has to be entering through a no pressure or valve or something, it clears when the engine runs, so its not on the positive side of any pump, not on the leak off system, diaphragms on the pump are dry (bottom and side diaphragms), so , I am thinking one of the injectors isnt closing fully and allowing air into the system when the engine is shut off?

Any ideas guys?

Or, is there a one way valve in the filter head somewhere? Im going to stick a new filter in it anyway.

nobber said:

Or, is there a one way valve in the filter head somewhere? Im going to stick a new filter in it anyway.

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There is a one way valve, it should be in a kind of metal adaptor on one side of the filter head. Still available new, as far as I know.

The air problem is caused either by leaks on the negative pressure side of the low pressure system, or by a split diaphragm in the lift pump itself.

Hi nobber, it does sound like problem at the filter. Often air will get in but you will not see fuel escape as despite the lift pump putting it in under pressure the injection pump has some suction pulling fuel and air into itself if there is a small leak.

you must have a leak,filter or lift pump are prime choices

I have noticed when I shut the engine down air bubbles come from the high pressure pump into the leak off, all my leak off pipes are clear pipe, as if the pump is emptying itself of diesel, I can hear diesel running back into the tank through the return pipe after shut down. I'm not sure its the lift pump as there is no lack of power, it runs lovely, starting from cold is an issue, it tries but dies, like a lack of fuel pressure at start up.

nobber said:

I have noticed when I shut the engine down air bubbles come from the high pressure pump into the leak off, all my leak off pipes are clear pipe, as if the pump is emptying itself of diesel, I can hear diesel running back into the tank through the return pipe after shut down. I'm not sure its the lift pump as there is no lack of power, it runs lovely, starting from cold is an issue, it tries but dies, like a lack of fuel pressure at start up.

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Have you checked carefully that the leak off pipes themselves are not leaking, those plastic pipes pushed on to the little banjos are not as good as the old metal leak off rail.

I would expect a 19j to run a bit rough from cold, especially a high mileage one that may not have been properly serviced.
I used to warm mine up for a few minutes after start up, and that had only done 20 odd k from new.

I don't think they are leaking, the bubbles seem to come from the pump, Su unless diesel is syphoning the pump through the leak off and drawing air in from somewhere I'm stumped, if that's the case the leak must be on the high pressure pump, the low pressure side of it, so it must be on the pipe from the lift pump to injector pump.

nobber said:

I don't think they are leaking, the bubbles seem to come from the pump, Su unless diesel is syphoning the pump through the leak off and drawing air in from somewhere I'm stumped, if that's the case the leak must be on the high pressure pump, the low pressure side of it, so it must be on the pipe from the lift pump to injector pump.

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Highly likely. See post 3.

nobber said:

I don't think they are leaking, the bubbles seem to come from the pump, Su unless diesel is syphoning the pump through the leak off and drawing air in from somewhere I'm stumped, if that's the case the leak must be on the high pressure pump, the low pressure side of it, so it must be on the pipe from the lift pump to injector pump.

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When I had mine, I used to replace all those plastic fuel pipes occasionally. They are only a few quid, the pipe goes hard after a few years, and the olives are meant to be replaced after use, but nobody ever does. Try a new pipe on the one you suspect.

I will check the connections, I'm not convinced its the lift pump, it was fine before the engine swap and there is no loss in power, its a sealed Delphi pump and its fairly new, but these things do fail. The fuel pipes are quite old and the connections a bit worn, it might be prudent to replace the old plastic pipes and make up new ones.

Turboman said:

When I had mine, I used to replace all those plastic fuel pipes occasionally. They are only a few quid, the pipe goes hard after a few years, and the olives are meant to be replaced after use, but nobody ever does. Try a new pipe on the one you suspect.

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There are no olives on my fuel pipes, they screw down into the pumps,

nobber said:

There are no olives on my fuel pipes, they screw down into the pumps,

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There should be metal olives, and small metal inserts inside to stiffen the pipes.

If there are not, that could well be your problem.

Could well be, so the insert crushes down on the olive when you tighten the nut? Thus allowing the nut to rotate around the pipe? I was wondering how that all worked, the olives, if still in there must be knackered after all these years of refitting the pipes.

nobber said:

Could well be, so the insert crushes down on the olive when you tighten the nut? Thus allowing the nut to rotate around the pipe? I was wondering how that all worked, the olives, if still in there must be knackered after all these years of refitting the pipes.

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Exactly.

Turboman said:

Exactly.

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I'll get some bits ordered up, in the meantime I will try and seal over the connections with reinzosil, if that sorts it I will know for sure that that is the problem.

nobber said:

I'll get some bits ordered up, in the meantime I will try and seal over the connections with reinzosil, if that sorts it I will know for sure that that is the problem.

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Just get the bits. Messing around with sealants rarely helps on fuel systems.

Turboman said:

Just get the bits. Messing around with sealants rarely helps on fuel systems.

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its a bodge for sure, Ideally I would like to fit rubber pipes and fuel clips but if olives are involved I doubt I could find the correct tails, easier to replace like for like.

nobber said:

its a bodge for sure, Ideally I would like to fit rubber pipes and fuel clips but if olives are involved I doubt I could find the correct tails, easier to replace like for like.

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You can buy the pipes ready made in any good LR parts place, or online. They are about 3 quid each.

Turboman said:

You can buy the pipes ready made in any good LR parts place, or online. They are about 3 quid each.

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Cool, thanks for the help man, greatly appreciated.