Diesel air lock HELP!!

Morning guys,

As per the title really I had my injection pump timing checked yesterday and all was found to be fine. Upon refitting the injection pump hard pipes and trying to start her back up she wouldn't start... So I cracked the injector pipes off and sure enough bubbles every where. It then fired up but had a bad knocking noise! I turned it straight back off and cracked all the injectors again... Sure enough more bubbles.

I've got it now so all injectors bar injector 5 are free from air. If I start it with injector fives hard pipe tight it nocks if I crack injector 5s hard pipe off lots of bubbles and the knock goes...

Is there and official way to bleed the fuel lines?

I really need your help as it's currently stuck at my cousins!

Thanks in advance

Just cracking the injectors normally does it assuming you bled the feed to the FIP first.

That's what I thought. And no I didn't how do I do that? Does a knocking sound right if you have an air lock in the fuel system?

Thank you

Littelwill said:

That's what I thought. And no I didn't how do I do that? Does a knocking sound right if you have an air lock in the fuel system?

Thank you

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Undo the feed pipe at the banjo on the FIP and cycle the in tank pump.
Can rattle a bit but never had much of a problem myself with bleeding.

Thank you for that Datatek! I'll try that.So just to double check I'm doing it right

Crack the FIP banjo
Cycle in tank pump
Tighten banjo
Crack all injector pipes
Crank engine
Tighten injector pipes
Start?

I know this is putting it simply but I need to find out what's causing it to get this air lock

Littelwill said:

Thank you for that Datatek! I'll try that.So just to double check I'm doing it right

Crack the FIP banjo
Cycle in tank pump
Tighten banjo
Crack all injector pipes
Crank engine
Tighten injector pipes
Start?

I know this is putting it simply but I need to find out what's causing it to get this air lock

Click to expand...

It will start as you tighten the injector pipes.
Filter/housing joint is a common source of air leaks. Pin holes in the injector pipes is another possibility as is leak off pipes.

I've replaced all the leak off pipes for good ones it just seems strange that injector 5 has so much pressure in it..

Littelwill said:

I've replaced all the leak off pipes for good ones it just seems strange that injector 5 has so much pressure in it..

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They are supposed to have a lot of pressure Just not a lot of air.

Haha I know that... So I'm going to try bleeding the banjo on the FIP and see if it's air in there. Does this remove air from the pump or air from the fuel coming to the pump?

Normally all you would need to do is crack all the injector pipes then get someone to crank and close them as airless fuel emerges. Crack number five and run engine close when you get airless fuel. If you are still getting a knock check you have pipes back in correct firing order on pump. Firing order is 153624.

Ok so pipes checked (thanks wammers) banjo bled and all pipes cracked and then tightened. The engine runs fine but just has that knock when injector five is tightened down. Any other ideas of things to try? There is still air coming out of injector five when the knocking starts and I crack it back off..

Littelwill said:

Ok so pipes checked (thanks wammers) banjo bled and all pipes cracked and then tightened. The engine runs fine but just has that knock when injector five is tightened down. Any other ideas of things to try? There is still air coming out of injector five when the knocking starts and I crack it back off..

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Run the engine and crack each in turn until you get airless fuel. If there is no air in the other injectors there should be no air in number five. Just persist until it clears.

Littelwill said:

Ok so pipes checked (thanks wammers) banjo bled and all pipes cracked and then tightened. The engine runs fine but just has that knock when injector five is tightened down. Any other ideas of things to try? There is still air coming out of injector five when the knocking starts and I crack it back off..

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Crack in the injector pipe? It's the long ones that fail most often. of course you should see some fuel as evidence if that is the case.

I'll keep persisting with it. I can't see any signs of a split or crack on the actual pipe. I've re checked the firing order to make sure the pipes are in the correct order and I don't think you can get them wrong tbh. Thanks for your help you two

W

Littelwill said:

I'll keep persisting with it. I can't see any signs of a split or crack on the actual pipe. I've re checked the firing order to make sure the pipes are in the correct order and I don't think you can get them wrong tbh. Thanks for your help you two

W

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If it was a cracked injector pipe you would see and smell diesel

tomcat59alan said:

If it was a cracked injector pipe you would see and smell diesel

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Also it is hard to imagine the pipe sucking air in with 3200 psi coming the other way.

wammers said:

Also it is hard to imagine the pipe sucking air in with 3200 psi coming the other way.

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Quite true matey, horses for course's.

Ok so thank you for your help I managed to bled injector 5 and it struck up and ran perfectly Ill keep an eye on it over the next week. The knocking has now totally gone!!

wammers said:

Normally all you would need to do is crack all the injector pipes then get someone to crank and close them as airless fuel emerges. ................................

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Do we have to run the in-tank pump via the relay for pre 1998 model diesels?

kapilamuni said:

Do we have to run the in-tank pump via the relay for pre 1998 model diesels?

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The lift pump will run when glow lamps are lit or when engine is running on pre 1999 models, also with cranking 1999 and on. So yes if you want to run the lift pump on a 1998 to bleed air, supply terminal 5 on relay 12 socket with 12 volts from battery positive. The one that is counter in orientation to the other three. The one nearest the front of the car with relay removed. That will run the lift pump.