MisterLion
New Member
Hello; I have a 2005 Mercedes SportCoupe C220 CDi (OM646 engine 110kW with air con) which, while it starts every time when cold, has developed a depressing tendency not to start when hot. But not all the time. If it's not going to start it turns over and clatters as if it's going to catch but doesn't. Give it three or four minutes and it will start—or possibly not. The thing is that it will always go eventually and then run perfectly until the next time it decides to mess me about. Mileage is a bit over 188,000 so it's likely that things will go wrong but this one has me and the service garage flummoxed (they are very good and I've been messing with cars for 50 years so I have some idea what goes on).
So far it has had four new glow plugs (two were dead and the other two were on their last legs). It's had four injectors; two failed the leakdown test spectacularly and the other two, again, were getting that way. Fuel pressure at the rail is very good which, on the face of it, seems to exonerate the high-pressure fuel pump although I am prepared to accept that that may have some sort of intermittent fault. Everything else checks out and their are no malfunctions noted on the dashboard; I have not been informed of any faults being noted by the diagnostic thingy.
The main symptom is that there appears to be insufficient fuel at the rail when the engine is hot. It's exactly the same now as before a lot of (expensive) work was done and it's getting a bit old. Leaving aside the fuel pump, which will be addressed when my finances have recovered a bit, are there any sensors that could cause this? Likewise, is there any way that air could be trapped in the system or should that bleed out by itself? I am fairly certain that there's no crud in the fuel tank or lines because the rest of the time there's no problem. Likewise there's no inrush of air if I remove the tank cap so no breathers are blocked.
Any ideas will be gratefully received…
So far it has had four new glow plugs (two were dead and the other two were on their last legs). It's had four injectors; two failed the leakdown test spectacularly and the other two, again, were getting that way. Fuel pressure at the rail is very good which, on the face of it, seems to exonerate the high-pressure fuel pump although I am prepared to accept that that may have some sort of intermittent fault. Everything else checks out and their are no malfunctions noted on the dashboard; I have not been informed of any faults being noted by the diagnostic thingy.
The main symptom is that there appears to be insufficient fuel at the rail when the engine is hot. It's exactly the same now as before a lot of (expensive) work was done and it's getting a bit old. Leaving aside the fuel pump, which will be addressed when my finances have recovered a bit, are there any sensors that could cause this? Likewise, is there any way that air could be trapped in the system or should that bleed out by itself? I am fairly certain that there's no crud in the fuel tank or lines because the rest of the time there's no problem. Likewise there's no inrush of air if I remove the tank cap so no breathers are blocked.
Any ideas will be gratefully received…
