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post #1 of (permalink) Old 19th May 2008 Thread Starter
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How To Replace Lag 1 dTi Fuel Filter

Heres a quick 'How To' on changing a diesel fuel filter.This details changing one on a Lag 1 phase 2 dTi,but the pricipals are the same for many other models.

Firstly locate the fuel filter.

Then disconnect any pipes and wire connectors so that the filter can be removed.The pipe work on the Lag dTi is clipped on and you have tio be very carefull not to damage the clips.They can be a little awkward to remove,but you need to be quite gentle with them,especially as after time the plastic beginnings to get fairly brittle.

It's a good idea to put some rag under the filter as you disconnect the pipes as this will catch any spillage.It's also a wise idea to wear gloves when handling diesel as the smell of it can be difficult to get out.

You can then release the filter from it's bracket......

Next you need to hold the filter over a bucket and undo the T30 bolt that clamps the filter together.This will release the two parts of the filter and the diesel in it will spill out.....hence the bucket.

Mark the position of the top part of the filter in relation to the lower part.There is a tab that sticks through a hole to locate it,but there is more than one hole to use due to filter being used for various applications.If you use the wrong hole(ooo-er missus) the filter won't line up with the pipe work when you come to re-fit it.....

You will then be able to remove the element which is the part you need to change.

With the new element you should get two new rubber seals,one for the bolt and one that fits between the two sections of the filter housing.It is critical that you get these right as not only will diesel leak but air will be drawn in if their not sealed correctly and this will cause starting and running well making a right mess!.

The filter and housing on this car was pretty clean,but there can be deposits left in the bottom of the filter housing.Obviously once it's apart the unit can be cleaned,I tend to use some brake and clutch cleaner to shift the deposits,but you could use some clean diesel and a paint brush.

When it comes to re-tightening the bolt that holds the filter housing together it is important to realise that the housing is plastic so it's important not to overtighten the bolt.You will feel the bolt stop when it reaches the end of it's thread,and that is tight enough.Over tighten it and you'll crack the housing and you'll need another one.

Once the filter is back together and re-fitted to the bracket and pipework/wires are reconnected the next part is to bleed the air out from the filter.This is done by squeezing the priming pump and undoing the bleed valve.....

As you squeeze the primer air will escape from the bleed valve until the filter fills with diesel,you will then have a jet of diesel coming out of the bleed screw(hence the rag to catch it!).Once you have a steady stream of diesel coming out,tighten the bleed valve and pump the primer until it goes hard.Check for leaks,and if all looks OK then start the engine.You can continue to pump the primer with the engine running until you are happy that all air is expelled.If the engine cuts out,pump the primer again before attempting to re-start the engine.

I hope this helps someone,and if anyone needs any more info I'm happy to help out.

The dTi is a conventional mechanical diesel system,the later dCi systems are common rail and have slightly different proceedures.
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Last edited by Lagdti; 19th May 2008 at 07:38 PM.
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