i still have to try the test where I pull the plug on the IMV and log the rail pressure. Trouble is, the thing I thoguht was the IMV might be the DRV going by our description above. I have circled the thing I thought it was in the attached picture.
As with you, the thing that confuses me is that everything seems to run perfectly when its actually running, so a sticky IMV or DRV would presumably cause some disruption while running.
Is there any way of testing the efficiency of the pump, injector spill etc without specialist equipment? I did think of one possible redneck method of testing whether the fuel viscosity has an effect but I'm not sure how easy it would be, and thats to have a bucket of cold diesel and dump the tank pump in there when it is hot - I'd have a good three or four hours to get it out - and see if it started with nice cold fuel. An easier, if somewhat more redneck way would be to fill it with a gallon of veg oil next time the tanks nearly empty and try a hot start. Veg oil is considerably more viscous than diesel, and hot is much the same as cold diesel.
I'm also starting to wonder if the ticking noise at idle is actually a failing piston in the HP pump or something pump related. I had up till this pont assumed it was the 4.0tdi timing chain issue as it has all the hallmarks. spray can rattle on start up followed by rhythmic ticking that sounds like its coming from the region of cylinder 4. I have gone over the engine with a stethoscope trying to track down the origin of the noise and to be honest it doesnt sound like its coming from the pump, but just listening by ear it sounds like its coming from that area. With the stethoscope it does sound a bit more like chain slap than a tick. Maybe I'll try posting a video in another thread to get some more opinions.
gill
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