Hi all

Over the past few days I've been trying to sort out some issues on my 2000 1.9 TDI Estate.

I had the coolant level warning going off every time I started, with normal coolant levels. So after some great advice on here I replaced the expansion tank, which has sorted that.

The car still has a problem though. It struggles to start in the morning after being on the drive all night. I've replaced the coolant temp sensor and all the glow plugs, but I've still got the problem. I read on here that it might be a leak in the fuel line. So I checked the clear fuel line when the engine was running.

Now and then, there are air bubbles running through it, but it gets especially bad, when I tap the fuel filter. I've put vaseline on the connections on the top of the fuel filter to check for the leaks there, but it's still the same. When the engine stops a large air bubble comes back from the engine and sits in the clear line.

Is this a problem with the fuel filter as it gets a lot worse when the filter is tapped up and down? I'm going to change the filter tomorrow anyway, but just wondered if there was anything else you guys think would help?

Thanks

Col

There is normally air bubbles in that line.

Found that out myself when trying to diagnose a running problem years ago only to check another car and it was exactly the same.

Ah ok, thanks for the info. Saved me a job!

Is there anything else I should be looking at to help resolve the starting issue? It's only first thing in the morning. Once it's been run, it's fine :confused:

Thanks

when was the fuel filter last drained?

My TDi has bubbles in the fuel line too.

Could your battery be on the way out? Mine got slight worse to start, and then one day it just refused to start - the battery had failed over night!

As stated bubbles in the clear fuel line are normal.

What is the ratio of air to fuel?

I take it we are not talking much more than 1:4.

Bubbles in the fuel supply line are not normal. They are a sign that air is getting into the fuel system, which in turn could cause fuel to drain back to the tank overnight and the pump has to then work hard to pull fuel. All hose connections on the draw side must be air tight. I have had a VW once with a hair line crack in the fuel filter where the clamp had been overtightened, and consequently the customer had trouble starting in the morning.

You can check either with a hand fuel primer, or by fitting a vacuum gauge on the fuel tank outlet and running the engine. If it doesn't pull a good vacuum you have an air leak between the fuel pump and the tank.....

Whilst you are right in saying there should be none, most of the TDi owners I know have some air bubbles and live with it. None of them have problems with cold starting.

Many have had stealer services that note this. When they ask about it, they are told that it is nothing to worry about.