Slow cold start.

Stevenine3

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W251 r class
Hi.My 320 r class is slow to start from Cold,so with a glow light on after starting I have replaced all 6 glow plugs.No light now but still slow start so I replaced the module , same again,my only concern before doing a leak test is ,replaced the original glow module which was a Merc part with a beru part and just wondered if the difference in part numbers might make a difference .Before the glow light came on it would start straight away .Steve
 

snoman

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Chrysler 300C CRD 2006
Could be a battery and/or alternator problem. At this time of the year, glowplugs don't play an important part. You need to make a few voltage measurements before jumping to conclusions:

Battery volts, fully charged, light load: 12.6V
Cranking volts: 10V or thereabouts
Alternator volts with engine running: 14.4V

How old is your battery? Do you have an OBD2 Code reader to check for fault codes? These codes would identify faulty glowplugs and/or module and also poor alternator performance; eg intermittent operation.
 
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Stevenine3

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Hi.No codes at all and it spins over quickly but can take maybe 6 or 7seconds to kick and start,when the glow light appeared after starting I could give it 2 heat cycles and it would start almost immediately. Since I have changed the glow plugs I have noticed that after starting there is no smoke like unburnt fuel as sometimes before making me assume there is a fuel problem.I have checked all lines and the pump and they are dry and clean, with 75k it does seem strange if there is a leak back
 
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Stevenine3

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So this morning stating took 6 seconds on a single heat cycle,it kicked and ran but there was some smoke so assume unburnt fuel.I have had a Merc friend scan the car he said that all glows are showing good and could well be leak back.
 

snoman

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Something you should be aware of, is that glowplug heating doesn't necessarily cease when the warning light extinguishes and it may continue for some time (dependent on ambient temp.) after the engine has started.
 
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Stevenine3

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Hi.I will clean throttle housing and change the fuel filter as I should have done this after doing the oil cooler seals .
It' a long shot but I have gone through the SH and despite it being all up to date I can' find evidence of a fuel filter since 34k and it' now on 76k.
 
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Stevenine3

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Hi.so this problem still exists,parked overnight and gave it 2 heat cycles and took about 10 seconds before the engine kicks and starts.some blue smoke so I assume sunburnt fuel .any thoughts .6 glow plugs replaced and a control module .
 

Taffy7hfa

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2004 ML350 Inspiration .2002 ML270 CDI .2016 Hyundai i30 1.6crdi.2014 Peugeot 308 1.6 HDI.
Hi.so this problem still exists,parked overnight and gave it 2 heat cycles and took about 10 seconds before the engine kicks and starts.some blue smoke so I assume sunburnt fuel .any thoughts .6 glow plugs replaced and a control module .
Hi, Unburnt fuel usually gives white smoke, blue would usually indicate burnt oil.
 

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