W211 doesn't start in the cold

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connashio1

Member
Joined
Nov 28, 2014
Messages
34
Car
W211 320CDI estate
Hi all,

My 03 W211 does not start easily when it gets down to 2 or 3 degrees overnight. It will start if I spray some coldstart into it however. The glow plug light goes off after 5 seconds or so , so it would appear they are fine. Is there a way of proving that they actually do work? I have an icarsoft scanner but not sure which menu (if any) shows data for the glow plugs.
Any suggestions welcomed....

Thanks Paul
 
See your rail pressure during crank. Usually it is injector tank line leak... Pressure should rise above 150bar before injection is allowed.
 
Hi
It is almost certainly rail pressure as stated by "mersum1es" stated above.
If you have a faulty glow plug(s) it should come up as a fault code in the engine ECU
 
Hi
It is almost certainly rail pressure as stated by "mersum1es" stated above.
If you have a faulty glow plug(s) it should come up as a fault code in the engine ECU
Thanks for the quick replies guys. Is it the black braided line that runs across the top of the injectors? I'll check the pressure with my scanner. How does adding a spray of coldstart get around this? Thanks again, Paul
 
Did the earlier 211's suffer from fuel line 'o' ring issues.
In truth it isn't one I've read of, but it is common on other earlier CDI's.
 
Thanks for the quick replies guys. Is it the black braided line that runs across the top of the injectors? I'll check the pressure with my scanner. How does adding a spray of coldstart get around this? Thanks again, Paul
As said above.

Until fuel pressure reaches a certain point the injectors may not operate hence the engine starting when you introduce "fuel".
 
Thanks for all the advice so far guys. One thing that doesn't make sense is this doesn't happen when it is not a cold night. Thursday just gone it was 7 degrees at 8.30am and she started first time. This morning (next day) it was 2 degrees at the same time and I had to use Coldstart to get her going. If it is a low fuel pressure issue is that possible to be temperature related? I'm not doubting what you've all said , just trying to get my head around it.

Thanks, Paul
 
Thanks for all the advice so far guys. One thing that doesn't make sense is this doesn't happen when it is not a cold night. Thursday just gone it was 7 degrees at 8.30am and she started first time. This morning (next day) it was 2 degrees at the same time and I had to use Coldstart to get her going. If it is a low fuel pressure issue is that possible to be temperature related? I'm not doubting what you've all said , just trying to get my head around it.

Thanks, Paul
Obviously pressures will change with temperature but I doubt that 7 degrees C would be enough to influence things.

Can you measure voltage at the glow plugs and relay?

Glow plug relay faults are not uncommon and I have heard that they may not throw a fault code that is picked up by many generic OBD scanners.

Is the car always parked in the same spot? Not sometimes on a slope?
 
Obviously pressures will change with temperature but I doubt that 7 degrees C would be enough to influence things.

Can you measure voltage at the glow plugs and relay?

Glow plug relay faults are not uncommon and I have heard that they may not throw a fault code that is picked up by many generic OBD scanners.

Is the car always parked in the same spot? Not sometimes on a slope?
I will try that at the weekend. If as you say the relay can be duff and no fault code generated that could explain the problem. Would the glow plug light come on and off as normal if the relay was at fault? Once I get the car running for a few minutes and it is warmed up it will start OK. On a less cold morning no Coldstart is required. At around £100 for the relay it isn't too expensive to swap out. To answer your last point, car is parked on flat block paving.

Cheers, Paul
 
I will try that at the weekend. If as you say the relay can be duff and no fault code generated that could explain the problem. Would the glow plug light come on and off as normal if the relay was at fault? Once I get the car running for a few minutes and it is warmed up it will start OK. On a less cold morning no Coldstart is required. At around £100 for the relay it isn't too expensive to swap out. To answer your last point, car is parked on flat block paving.

Cheers, Paul
Paul.

All sounds sensible.

I think the relay may store codes or can be interrogated but propably needs Star.

ICarsoft or an Autel scanner might pick something up.

Whereabouts in the country are you based? Do you have a local MB independent close by?

Good luck! 👍👍

David
 
Don't keep using cold start, the car may become addicted to the ether with continued use and the will not start without it. Also been known to crack piston crowns.
 
Don't keep using cold start, the car may become addicted to the ether with continued use and the will not start without it. Also been known to crack piston crowns.
Addicted to it? 🤔😜
 

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