First start or the day and smoke

jshodgson

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hi
The first start of the day takes a long time (6-10 seconds of cranking) compared to all future starts (1-2 seconds). I also noticed today that there was a bit of white smoke too on the first start. Today the first start was at 2pm and it was about 20 degrees outside.
Anything to worry about or look to repair? I've never had this on any of the diesels I've owned before.
Thanks
 

John Laidlaw

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The white smoke is usually due to water/condensation- hopefully just in the exhaust!
The longer cranking may be just your glow plugs- any idea when they were changed last (if at all!)
That would be my initial thoughts although there are many and varied reasons for both...
 

LostKiwi

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Does the white smoke smell of diesel or is it relatively odourless?
If its odourless then its just condensation.
If it smells of diesel then its likely a bad glow plug or an air leak somewhere.
 
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jshodgson

jshodgson

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Looks like it is just condensation as today there was none and it started nice and quick. Thanks for the replies.
 
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Hi this is my first attempt at helping. I think my car has the same engine and fault, I've replaced all six heater plugs and the original relay. If I turn the ignition on and wait for the heater plug light in the clocks to go out then turn ign off then start cranking it fires up very quickly. I'm sure the problem lies with the heater plug system, where, I wish I new, but starting like its a 30 year old diesel works but shouldn't be needed on what was a £35k car.
 
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jshodgson

jshodgson

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Thanks, I'm hoping my smoke was condensation (as mentioned above) as I haven't had any since. I have tried your 'turn ignition on then off then crank' and mine also starts quickly doing that. Hope you get yours sorted soon.
 
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jshodgson

jshodgson

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That is the correct way to start it. Wait for light to go out.

Ian.
Is it normal to turn on the ignition till the light goes off, then turn off the ignition, then start it? I have never had to start any of my previous diesels like this, usually I just wait for the light to go out and then turn the key.
 

John Laidlaw

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I've never done that on any diesel. Always turn on ignition, watch glow lights until they go off, start.
Modern diesels start immediately or should do unless there is a glow plug or relay issue (primarily)
I hadn't read the post above correctly first time!
 
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Does anyone know if the OM642 engine is still being fitted in new Mercs? I can't see the starting procedure being as slow as it is in mine, and probably many others. Direct Inj diesels have been made for years now, and in our climate gave practically instant starting in all but extreme winter weather. I read somewhere that the OM642 engine has a comparatively low compression which, to my mind, makes it heavily dependant on heater plugs to help raise the temp created by compression to a point where ignition can start. If I crank mine from cold, when, it starts it produces a small cloud of smoke which is the excessive diesel being burnt off that was squirted in during all that cranking. That diesel helped raise the compression by assisting the piston rings seal thereby increasing compression pressure. But I don't think it's the best way to start it though.
 
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