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MB Paul
MB Paul, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4317
Experience:  Mercedes Benz Qualified Diagnostic Technician
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My Mercedes Diesel E220 cdi w210 will not start in the morning

Customer Question

My Mercedes Diesel E220 cdi w210 will not start in the morning if the temprature is below 4deg C.
If I take the wife's hair dryer , direct the hot flow on to the Diesel Pump on the front of the engine after 10 minuets the Car will start.
After warming up the car is fine for the rest of the day . I have had the Injectors checked , the mas air flow sensor checked all without sucess. Can you advise ? tony
Submitted: 4 years ago.
Category: Mercedes
Expert:  MB Paul replied 4 years ago.

does the glow plug light come on & go out as normal when you first switch on or does it come back on for a few minutes after starting?

Best regards, Paul
Customer: replied 4 years ago.

Thanks for your reply. The glow plug light comes on as normal and after the warm up period 10-15 seconds the lamp goes out, at this point I attempt to start the engine the lamp does not come on again when cranking but the engine does not start.

If I warm up the diesel pump with the hair dryer for 10 mins the Glow plug lamp is illuminated for only a few seconds but the engine will then start, albeit with a lumpy engine rythme


P.S. The glow plugs have twice been replaced. tony

Expert:  MB Paul replied 4 years ago.
Hi Tony,

Sorry for the late reply - I have been busy today & away from my computer.

Well it would appear that the glow plugs are functioning correctly but there are still quite a few possibilities.

I would first recommend a check for fault codes on a diagnostic tool to see if any codes are stored as there are many things that could cause this problem.

A common problem is down to low fuel pressure in the fuel rail - this can be down to many different things:

The first & most common problem is air being drawn into the low pressure lines - check for any signs of fuel leaks around the engine. Often no fuel will be visable but air can still be drawn in - check for signs of air in the low pressure lines from the filter to the fuel pumps & upto the rail. If air is present then I would replace the O rings at the end of the low pressure lines. This may explain why the car starts easier with a hair dryer on it as warming up the seals & pipes may cause them to expand just enough to provide a better seal from air being drawn in.

The fuel filter can also cause problems & would replace with a genuine filter.

Another common issue is with the injectors - when faulty these flow too much fuel back down the return line, this again causes low rail pressure preventing the engine from starting. These need to be checked with special measuring tubes to check the returned amount of fuel.

There are many other issues that could be causing this but would have the above checked first.

Best regards, Paul