2.0 tdi vacuum pump?

[petrolhead63]

the 2006 2.tdi avant has for a while had an idle speed that increases and sometimes settles down to normal but I have not found the cause.
More recently it has started making a whirring noise, it can be heard in the car. This seems to be coming from the vacuum pump possible on the back of the engine (its at the back anyway)
In addition I have had for a long time the very occasional whif of unburned diesel waft into the cabin...but never found a leak.
It this car a combined vacuum and fuel pump.
I wonder if it is responsible for the diesel whif, the whirring noise and also the sometimes fast idle?
Are there know issues with this pump I could look for...Thanks.

[Crasher]

Open the fuel filter up and see if it and the fuel are filthy thick, diesel carbon black.

[petrolhead63]

Crasher thanks, as it happens I have a new fuel filter to fit, I was not thinking it was related just planned maintenance. What is your though on that line related to my problems? Cheers.

[Crasher]

The tandem pumps are very prone to leaking their lubrication feed into fuel pressurisation side which gradually contaminates the fuel system to the extent the fuel tank is coated in a thick black gunge and gradually the fuel loses its Cetane rating and will not burn properly. The quick way to check is to open up the fuel filter and if it is ditched, change the tandem pump, drain the tank and then refill using a diesel injector cleaner. After a couple of tanks the system should come clean BUT the in tank lift pump often fails, to drain the tank you can run the lift pump and pipe the fuel at the filter into a container so you can find out if the pump works. Some people have suggested adding a little petrol to the first full fill which makes sense but I can’t recommend that or the mix ratio. We like to fit a new tank delivery complete unit and with the tank drained, get an arm and cloths in there and wipe it as clean as possible, not a pleasant job.

[petrolhead63]

Hi, I have changed the filter now and first drained it. The fuel was fairly clean and clear although it darkened as I left it with dirt coming out. (I know the filter has done 50K plus though!)
I have now cut the filter open, the paper element is black, it rubs off onto fingers. It is not thick and really gungy.
If I poke a screwdriver into the paper vaines I can scrape a little black filth out which wipes off onto a cloth.
I am not sure what to expect in a car filter, I am used to boat ones which actually plug up such is the rubbish and bug in tanks.
Is a car filter with white diesel (not red) usually black inside after many miles?

[Crasher]

If it was the typical failure the fuel in the canister would be black and thicker than clean diesel, you may have a slight weep but at 50K the filter will get quite dirty so at the moment I would not suspect the tandem pump.

[petrolhead63]

Thanks, I thought as much...the fuel was not thick in any way in the filter. The car has near 190K on it too so the fuel tank is likely a bit grubby! The whir seems to have stopped at the moment...as has my aircon! though it has gas pressure.
The fluctuating idle speed....I cant find any vacuum leaks...i wonder if the cheap chinese throttle valve put on it some time ago may be the root of that? It simple idles at about 850 (correct) or up to 1000 (too fast) it can be idling away at 850 then just rise for no reason. Turn engine off, restart and it idles at 850 again ...for a while!

[Crasher]

And no fault codes? It isn't a very early DPF car is it?

[petrolhead63]

hi, no fault codes (but will check again since last reset/driving. It had fault code and MIL light when the throttle valve went duff, although it drove fine!
no DPF either I believe. (2006 car)