Fuel filter on a 220cdi 646 - prime it or crank it?

Yugguy

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Hello all.

Has anyone changed the fuel filter on a 646? Does it really need priming?

I've done the filter on my diesel focus and my diesel bora, and never bothered priming it, just cranked the starter for about 15 seconds til it fills and starts.

I've looked on youtube and some videos show priming, some don't.
 

M80

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It will crank it through,
but I usually decant the diesel from the old filter to the new.
 

LostKiwi

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I always primed filters when I had diesels.
 

Uncle Benz

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I always fill the new filter. Not only will you have to crank for an extended period before it will start, I always worry that either the starter motor will fail due to overheating or something else in the fuel system will be buggered up by drawing air. HP pump for example. Lack of lubrication can be terminal on those.
 
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Yugguy

Yugguy

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Cheers, not sure about putting diesel from dirty filter into new one though?
 

Uncle Benz

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Cheers, not sure about putting diesel from dirty filter into new one though?

Probably ok as long as you pour it into the filter "in" pipe. Seems bonkers pre-dirtying a new filter though :)
 

Westheath

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If you don't have an electric fuel pump priming is beneficial.

I use a vacuum oil drainer on the fuel filter to HP pump pipe
and draw the fuel up from the tank filling the filter then pop the HP pipe back on.

Saves cranking especially on the S Type 2.7 engines such a pig to get started after a filter change.
 
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Yugguy

Yugguy

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That's a good idea, I hadn't thought of drawing from the tank.
 

ajlsl600

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i always fill the filter , with fresh clean fuel then when it starts i keep it at high idle while it runs the fuel thru . some cars can be a bit of a B for this ,D4D for example,previously had to pressurise fuel tank, avoided when following above method
 

M80

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Probably ok as long as you pour it into the filter "in" pipe. Seems bonkers pre-dirtying a new filter though :)

If it's taken from the 'out' of the old filter it's already filtered. It doesn't matter which pipe it's filled through on the new, but if prefered into the 'in' of that would filter it again.
 

Uncle Benz

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If it's taken from the 'out' of the old filter it's already filtered. It doesn't matter which pipe it's filled through on the new, but if prefered into the 'in' of that would filter it again.

Personally I'd avoid pouring anything into the "out" port of the new filter. Often the new filters come with a plug over the out port to prevent anything entering before you put the hose onto it. Although fuel drawn from the out port of the old filter is clean, the vessel or funnel used pose a risk of contamination. With appropriate care, probably safe, but for me - bad working practice.
 
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Yugguy

Yugguy

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Well that was pretty easy. Just used my hand vacuum pump to draw fuel through the new filter. Reckon I'll change it every 30k.
 

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