My Uncle has asked me to find out whether any diesel experts on here might have a solution to a problem he's been having with his 1996 Mondeo 1.8TD. I know it isn't a Vauxhall/Isuzu engine, but the symptoms might ring a few bells with some of you - apologies for the essay, but at least the problem's been described thoroughly.
He says; The engine runs on the Lucas CAV system. The problem started around the 105k mark, all injectors were fully serviced at 98k miles, fuel consumption and power is normal. It's now done 127k miles and the problem has not noticeably deteriorated. Air intake through the supply side of the diesel pump has been eliminated (Tank, feed pipe, fuel filter housing etc) by temporarily connecting a transparent hose from a clean gallon can containing diesel, suspended above the engine and fed directly in to the diesel pump. The problem manifested itself even when it was clear that no air was entering the fuel pump i.e. there were no air bubbles to see passing through the transparent hose.
On starting the engine, it runs ok for a few minutes. Occasionally (More often than not) at idle, the engine falters as though a little air is passing through the fuel system, while at the same time, the exhaust emits quite a lot of smoke (Not blue - I am not losing engine oil). This can also happen while waiting at junctions. If left, the engine may splutter erratically for some time, or it may right itself, only to start up again after a couple of minutes. On other occasions, it might be fine and it doesn't splutter at all. Also, while cruising at about 30Mph in forth gear (Idle revs), the whole car can judder while the apparent misfire takes place. This is usually remedied by dropping in to a lower gear or by accelerating. If I had to guess, I would say that the smoky exhaust gas is un-burnt fuel. The only way I have been able to improve matters is by increasing the idle speed to around 1000 - 1100 but this still doesn't eliminate the problem entirely. I should also add, that since changing the air pollen filter which was well overdue, I have noticed the occasional smell of fumes entering the cab, though, I'm not really sure whether they're finding their way in from the rear of the car or the engine compartment - I have not seen any smoke leaking from the engine area or exhaust system. Aside from this, the car is fine, performance, fuel consumption, engine oil consumption and general handling are all normal. Does anyone have any ideas?
Thanks for any help