fuel filter draining?!

toby_2009 · Jan 5, 2015

Hi all,

The fuel filter warning light on my 2003 Disco TD5 has been coming on recently, it tends to happen just before and after starting it and it goes out within about 30 seconds.

Is it worth trying to drain the water from the fuel filter? If so then do I just disconnect the sensor, unscrew it and let the contents of the filter empty into a bucket and then replace the sensor and connector or which the whole tank empty?

If I drain the filter as described above then can I just start the engine as normal or do I need to put the engine into a purge/prime setting? If so then how?

I have read loads of threads on the topic but am still confused.

If the above doesnt work then how can I identify if it is the filter or sensor which is at fault?

Thanks,

Toby

iansoady · Jan 5, 2015

The sensor is notoriously unreliable. Mine used to come on when it was raining heavily.....

In theory you just slacken off the drain (the bit on the bottom of the filter housing) until water stops flowing and diesel starts - then tighten up again and off you go. In practice I've never had to touch mine.

toby_2009 · Jan 5, 2015

Hi all,

Situation update, I have tried draining the water (didn't seem to be any) and it made no difference. However on a very detailed and laborious review of the service history, it would appear that the filter hasn't been changed for 40,000 miles (when it should be changed every 24,000).

As such I am ordering a new filter and sensor (both third party) which I will fit myself. The Haynes manual says that there is no need to bleed or prime the fuel system following a fuel filter replacement however lots of the threads online suggest that it is necessary. What do you guys reckon?

Also, when I unscrew the old filter will the fuel flow out from where it was screwed in or not? (i.e. Will it **** a full tank of diesel across the drive?

Thanks,

Toby

notenoughtime · Jan 5, 2015

You will loose some diesel when you unscrew the filter, I usually fill the filter with clean diesel before screwing back on, but thats all personnel preference

toby_2009 · Jan 5, 2015

notenoughtime said:
You will loose some diesel when you unscrew the filter, I usually fill the filter with clean diesel before screwing back on, but thats all personnel preference

Thanks, does the diesel stop flowing shortly after removing the filter?

What is the reason for filling the filter before attaching it? And how would I go about doing that?

How about priming the system?

Toby

Disco DJ · Jan 6, 2015

Unscrew the bottom sensor and "some" diesel will come out. Then unscrew the filter, which will still have some in it too (just tip it out). I use an old plastic bin, but you'll only lose a litre or so.
Then, before screwing the new filter in, just pour some diesel in the top from a fuel can (this will stop most the air getting in the system)
If you don't do this you will probably need the "purging" procedure instead before it'll start!

DIFFLOCK66 · Jan 6, 2015

toby_2009 said:
Thanks, does the diesel stop flowing shortly after removing the filter?

Yes....Unless for some reason you've got the ignition on and the fuel pump is running!

Necessary or not, the purge process is very easy to do and after all you've introduced a bit of air into the fuel system. Whenever I change the fuel filter, I use the purge. Assuming the new filter's been fitted then turn the ignition on and rapidly pump the accelerator pedal until the amber "service engine" (whatever it's called) light comes on, then leave the Disco alone. You'll hear the fuel pump run & stop a few times. Once the light's gone out then fire her up.

iansoady · Jan 6, 2015

Just one point to watch - as well as the big rubber seal round the outside of the filter there's a smaller one inside round the thread. It's easy to leave the old one in position and end up with 2 causing leaks.....

50 pence · Jan 6, 2015

iansoady said:
Just one point to watch - as well as the big rubber seal round the outside of the filter there's a smaller one inside round the thread. It's easy to leave the old one in position and end up with 2 causing leaks.....

A very good point together with filling the new filter with derv.
I do mine this way and it always starts straight away.

fuel filter draining?!

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