Hi, i have ordered my hex can cable and fuel filter and it looks a fairly straight forward procedure however since i will be using vcds to prime the system does that mean after i have removed all the diesel from the canister and cleaned it then put the new filter in do i have to top up with diesel or leave it empty and let the vcds software do it..Thanks
Advice on fuel filter
- Thread starter den911
- Start date
I swaped out the filter and left the diesel in there. Then primed multiple times with VCDS to ensure it was brimmed and no air in there. Started up first turn of key without any issues. As long as you prime it fully it will be fine.
Never used Vcds to prime the fuel when I had a bkd. Just 1/2 fill the bowl, fit filter and top cover and stated ok
When I changed my filter recently, I made sure the canister was full of diesel/cleaner before I sealed it. I don't know how much fuel is pumped to the canister when VCDS primes the pump. Better safe than sorry. I primed it 3 times around 30 seconds each. The car started right up and ran smoothly without any issues afterwards.
The earlier (i.e NOT common-rail diesels) don’t need any sort of priming AFAIK with VCDS as the fuel systems are self-bleeding.
The later common-rail diesels DO need to be primed to with VCDS (to be safe) or damage MAY occur to the high-pressure fuel pump.
I learnt this the hard way as I’ve often changed the fuel filter on my BKD-engined A3 (in fact SootySport’s old car!) and when I was asked to do the same to my niece’s 2011 A3 1.6 TDI cabrio (common rail engine) didn’t think anything of it as the fuel filter & housing were identical on both cars despite almost 5 years difference in age between them (both systems were of the UFI-brand filter type ).
However , after changing the filter on my niece’s car (luckily I didn’t empty the filter housing of old fuel , just removed old filter and put new one in) it would not re-start, it would turn over happily enough, it just wouldn’t fire!
It was only after I then Googled as to why it wouldn’t start I came across quite a few horror stories about the need to prime the fuel filter housing on common-rail (CR) engines and that if this isn’t done and the engine-driven fuel pump is run dry (which can happen if the filter housing is totally emptied/dried before putting the new filter in) then severe damage CAN result.
Luckily I have VCDS and was able to prime it and got the car to start, with (touch-wood ) no problems since.
Whilst I may be over -dramatising things , I really would strongly recommend that if you have a CR engine then to prime the filter housing to be safe, or get a garage to do the job if you are in any doubt.
If it isn’t common-rail then no need to as already said , the job is a doddle.
The later common-rail diesels DO need to be primed to with VCDS (to be safe) or damage MAY occur to the high-pressure fuel pump.
I learnt this the hard way as I’ve often changed the fuel filter on my BKD-engined A3 (in fact SootySport’s old car!) and when I was asked to do the same to my niece’s 2011 A3 1.6 TDI cabrio (common rail engine) didn’t think anything of it as the fuel filter & housing were identical on both cars despite almost 5 years difference in age between them (both systems were of the UFI-brand filter type ).
However , after changing the filter on my niece’s car (luckily I didn’t empty the filter housing of old fuel , just removed old filter and put new one in) it would not re-start, it would turn over happily enough, it just wouldn’t fire!
It was only after I then Googled as to why it wouldn’t start I came across quite a few horror stories about the need to prime the fuel filter housing on common-rail (CR) engines and that if this isn’t done and the engine-driven fuel pump is run dry (which can happen if the filter housing is totally emptied/dried before putting the new filter in) then severe damage CAN result.
Luckily I have VCDS and was able to prime it and got the car to start, with (touch-wood ) no problems since.
Whilst I may be over -dramatising things , I really would strongly recommend that if you have a CR engine then to prime the filter housing to be safe, or get a garage to do the job if you are in any doubt.
If it isn’t common-rail then no need to as already said , the job is a doddle.
Managed to change the filter today and considering I have done just 1300 miles since I purchased the car with a full service and the fuel filter ticked as done I must be using some awful diesel ,this is why I always service a car myself after a purchase as it’s obvious it’s not been changed
