Mercedes: 85 190D Hard to Start Condition, fuel air mixture, water separator

Question
QUESTION: Hello, I have just taken ownership of a 1985 190D. The car runs flawlessly with one problem. When sitting for a long time, like 5 hours or more, it does not want to start back up without pumping the accelerator a dozen times or more. I am worried about what will happen when it starts to get really cold up here and it is combating that as well as my possible fuel pressure leakdown issue (my guess) Once it has been running for a few minutes, it starts like it should. Is there something that would cause it to lose fuel pressure and that it is why it is difficult to start?

ANSWER: Michael,
Leak down can be the fuel rail check valve allowing fuel to leak back to the tank. Or, if the injectors are dirty or sticking, it can allow fuel to weep out into the manifold. Or if the glow plugs are weak you are not getting enough heat on cold start to get the spontaneous combustion you need for a quick start.
Make sure your water separator and fuel filter are clean and clear of contaminants. I would get some fuel treatment from a truck stop. Preferably bio-diesel as it has very good cleaning ability.
If your winters are severe, A block heater is most definitely a required add-on to keep your block warm enough to get the quick start you expect.
Good Luck
Rob




---------- FOLLOW-UP ----------

QUESTION: Okay, I have an update. When my car is plugged in, it starts very quickly, even when sitting for 8+hours could this be an indication of faulty glow plugs?

Answer
Michael,
You did not indicate what mileage on the engine. But if there is ware on the engine rings, then the compression would be less that normal. You would run a compression check to determine if the cylinders are within spec.
Excess smoke during acceleration or under load, can indicate either worn rings, or worn injectors also.  
Other wise the glow plugs may need to be replaced. The hotter the upper cylinder prior to squeezing the fuel air mixture the better light off of the fuel you get.
Or if you are where you can keep the vehicle plugged in, it would still be better on the engine to have it start quickly rather that put such a strain on the starter.
Good  Luck
Rob