Diesel auto bleeding.

[rotrax]

Is your engine a common rail diesel. Common rail diesels do not need bleeding but mechanical injector diesels do as any air the the injector line will prevent the mechanical injector opening.

No, rotary pump.

The filter changes dont affect the high pressure side of the pump, so with the ignition on, it self bleeds the low pressure side.

Simples.

Island Packet incorporate an electric pump for easy bleeding, my new Facet copy makes that redundant.

 

[Rappey]

(the "rail") that is permanently pressured to between 4 and 6 bar.

More like 250 to 300 bar when cranking, hence being very carefull messing around with a running engine. Common rail when running can be 1200 to 2000 bar.
The figures you quoted are more like the pressure from the fuel lift pump to the high pressure pump.

 

[Moodysailor]

More like 250 to 300 bar when cranking, hence being very carefull messing around with a running engine. Common rail when running can be 1200 to 2000 bar.
The figures you quoted are more like the pressure from the fuel lift pump to the high pressure pump.

It does depend on the design, some use a HP rail as you say. Some generate the pressure within the injector, it depends on the system. Volvo Penta for example use both types on different engine models.

The theory is still the same regarding air bleeding ?

 

[dankilb]

Very informative thread, this...

If you have ever heard a diesel engine start up on less than all cylinders after a service, you have experienced this.

Yup the van engine sounds like a bag of spanners when cranking/bleeding after a filter change. Always wondered if it was air being squeezed through the injectors (even though instinctively know this isn't really how they work) - but makes sense that it's fuel only going to certain cylinders while the air is forced down the return.

I wonder, then, whether the Beta/Kubota pumps also bleed down the return with an electric pump to help it along?

 

[Moodysailor]

Very informative thread, this...



Yup the van engine sounds like a bag of spanners when cranking/bleeding after a filter change. Always wondered if it was air being squeezed through the injectors (even though instinctively know this isn't really how they work) - but makes sense that it's fuel only going to certain cylinders while the air is forced down the return.

I wonder, then, whether the Beta/Kubota pumps also bleed down the return with an electric pump to help it along?

I would expect that the electric pumps are specced to provide enough pressure to overcome the non-return valve in the return line fitting. This would allow them to purge most of the air. The Fisher Panda generators did this, they use the Farryman & Kubota engines.

 

[jwilson]

Yanmar 3YM series certainly seem to bleed themselves: after draining fuel tank or disconnecting fuel lines it just seems to start again, sometimes might take 2-4 seconds to fire instead of almost instant as usual. Non common rail, mechanical fuel pump.

 

[snowbird30ds]

Being a stinky I have twin vp tmd41's, I fitted a non return bleed nipple in place of original bleed screw on second filter and use pela oil extractor to suck fuel through at filter changes, takes no time at all and very simple.

 

[Moodysailor]

Being a stinky I have twin vp tmd41's, I fitted a non return bleed nipple in place of original bleed screw on second filter and use pela oil extractor to suck fuel through at filter changes, takes no time at all and very simple.

Top tip, I used to do this a lot when I was a marine engineer.

 

[Whitlock]

I would expect that the electric pumps are specced to provide enough pressure to overcome the non-return valve in the return line fitting. This would allow them to purge most of the air. The Fisher Panda generators did this, they use the Farryman & Kubota engines.

Don't get me started on Fischer Panda generators and their Farymann engines. The biggest load of rubbish that I have ever wasted a lot of money on. No dealer network, over complicated and an engine that will not last much longer than a portable generator.

 

[Moodysailor]

Don't get me started on Fischer Panda generators and their Farymann engines. The biggest load of rubbish that I have ever wasted a lot of money on. No dealer network, over complicated and an engine that will not last much longer than a portable generator.

Haha, yes - I have no idea how they managed to do that to those engines on the 3kW range, i've seen those work for decades in other applications! The Kubota engines on the larger sets are pretty bullet-proof though.

No idea what they are like now, but back when I was fixing them, it was the accessories that let them down (fuel pumps, water pumps, exhaust elbows, etc).

 

[alancollins]

Snowbird Where did you get the non return nipple?

 

[snowbird30ds]

Ebay for the nipple, they are for brake calipers and come in different threads, about £25 each if I remember rightly, saves a lot of hassle.
They have a ball and spring inside, nip the top open, suck through, nip up, bled!
If air has got through to injector pump it still needs bleeding but it rarely does at filter change.

 

[Tamar]

My Perkins 100 needs bleeding when I change the filters. I put an outboard motor fuel bulb in the fuel line which soon fills the system, then just use the lift pump to fill the secondary filter, takes around 3 minutes. I recently removed the injectors so had to crack open one of the injector pipes to get the air out.