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Matt
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 21973
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Mercedes Sprinter 2007. Been running ok all day then wont start.

Resolved Question:

Mercedes Sprinter 2007. Been running ok all day then wont start. Temperature/ thermostat light staying on after ignition lights go off. Leave for around an hour and all lights go out, van starts.
Submitted: 3 years ago.
Category: Mercedes
Expert:  Matt replied 3 years ago.

Hello

I'd check that you're getting full power to the glow-plugs, they pull a lot of current so take care when checking but see if the relay is clicking when the ignition is turned on first and also check the fuse if this is OK check to see if the engine earth strap is also OK.

If the plugs haven't been changed in the last 20K then they may have to be replaced.

You can test the glow-plugs with a multimeter by measuring the resistance across the plug ( between the power connection and the body) it should be around 4-8ohms if its tending to infinity / open circuit the plug is faulty or by using a clip on current clamp, either on the supply wire to glow plugs or onto engine earth, with glow plug light on you should see 15-20amps for each glow plug fitted, 4 cylinders would be approximately 60-80amps.

and it may have developed an air leak on the fuel supply pipe from the tank to the engine. The engine has no separate lift pump and relies on the built in one in the injection pump. If a leak has developed on the fuel suction pipe then air entering the system will air lock the pump.
Try pumping up the fuel using the hand pump in the engine bay on the filter housing, then crack off / loosen each injector pipe in turn while cranking the engine and getting an assistant to operate the primer. This will expel air from the injection side and the engine should fire up. The problem will be cured by checking the supply pipe along its length for signs of leakage and repairing any you find.

If you daub each pipe joint with heavy grease and the issue goes away then wipe the grease away one at a time to highlight the problem joint


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