'Ugly Betty' metallic noise
Q Following your recent comments, I took your advice and bought a 2005 Citroën Berlingo 1.9 non-turbo diesel with 74,000 miles, loads of history and due a cambelt change for £1500, naming her ‘Ugly Betty’! To date, I have given her a full service, changed the cambelt, auxiliary belts, tensioners and water pump, removed and cleaned the EGR, repaired two split pipes to the EGR, tidied the loading area, fitted a replacement rear parcel shelf, a new battery and a decent Pioneer stereo/cd player and speakers, used plenty of injector cleaner, and given it a deep, deep clean.
However, two faults are niggling me. When the tank is approaching a quarter-full, the engine begins to hesitate then surge. The car then accelerates better, giving an indication that the performance potential is better than I am experiencing on a full or half-tank.
Also, on acceleration, a light metallic noise is evident within a small, low rev range – it sounds exactly like a petrol engine pinking. I have excluded pulley wear and a very experienced diesel engineer is unsure of the cause of both faults, but does not think the pump is the culprit as the vehicle otherwise runs perfectly. Joe
A The fuel level-related performance is a strange phenomenon and my first suggestion would be to check the pick-up/strainer in the fuel tank. Having said that, the usual scenario is for the power to decrease as the level in the tank lowers, but you may find that the float level for the fuel gauge is somehow having an effect on the pick-up.
As you have already checked the crankshaft pulley as the source of the pinking noise, this can be discounted. Another possible reason is the EGR valve sticking closed. This can cause the combustion temperature to rise, resulting in the pinking noise. As you have attended to the EGR valve and the vacuum hoses, this should not be causing any problems, but I would still check its operation.
Although I have not heard the noise, I will throw in the broader possibility that it is coming from a resonating exhaust or bracket, although I am sure that your diesel engineer would have been able to differentiate on the source if this was the case.
The final suggestion regarding the noise comes from Autodata, which informs me that the air filter housing retaining clips are a common failure point and may need renewing, although I am fairly sure this is not the issue with your vehicle.