Changing a 110 tdi SX Fuel Filter

[Slicker 1]

Hi,

Leon Mk1 1.9tdi 110SX, ASV engine, Fuel filter change.

First time I have changed one of these. It seems to be a complete unit held by a side clamp and not a separate element which I am used to on other VAG stuff and will necessitate disconnecting the fuel pipes.

1. The new filter will obviously not have fuel in it afterwards. Will the system need bleeding afterwards...if so, how is this done?

2. When buying the filter would it be best to also buy some replacement pipe retaining clips?

Any other pointers or tips would be much appreciated.

 

[Muttley]

Pull out the spring clip and remove the thermostatic regulating valve in the return line, complete with hoses. Don't lose the clip. You don't have to undo the hoses.

Remove the feed line hoses. They should be fitted with reusable spring clamps. If not, you'll need some little jubilee clips or something similar.

Undo the fixing bolt and remove the old filter.

Fill the new filter with diesel and secure it in the bracket.

Use the new o-ring (that should come with the filter) and fit the thermostatic valve to the new filter.

Fit the feed hoses to the new filter.

Start the engine and check for fuel flow and any leaks.

The pump is self-priming and there should be no need to bleed the fuel system.


The thermostatic valve allows some of the returned fuel, which is hot having been through the distributor pump, to mix with the tank fuel after a cold start.

 

[Slicker 1]

Thanks Muttley for the input,brilliant, explains a lot.

The diagram explains a lot. I had already sussed that putting the old diesel back in was not a good idea.
I assume the filter is in a relatively low pressure area?, but when I disconnect the line from the tank, do I need to block it off? Just wondering if it will syphon from the tank.

Once again thanks.

 

[Muttley]

The TDI 110 is a "normal" distributor pump diesel, and there is only one pump in the system. No lift pump in the tank means that the distributor pump will be sucking fuel through the filter, which makes it low-pressure from that point of view. Excess fuel not used in the injection cycle will be returned back to the tank, but the system isn't pressurised.

There should be no syphon action. The fuel is more likely to drain back into the tank. It would be wise to put some paper towels down under the filter to catch any spill from the fuel lines. The filter has a drain at the bottom (for letting out water that's been filtered out of the fuel, should be done at each service), and you can drain the filter from here if you're nervous of spilling some as you manoeuvre the filter out of the bracket.

 

[Slicker 1]

Thanks again for the help......appreciated