OM642 cold starting

[HERBIEMERCMAN]

My car has 250,000 on the clock and new glow plugs were fitted recently, the orange light goes out after 6 seconds and starts as soon as i touch the key, instantly, no matter how cold it is. I have always made my own fuel additive which is 30% standard mineral 2T oil and 70% of cetane, circa half a litre to an 80 litre tank, this gives me smooth running and about 3 mpg more, it will also help cold starting as the cetane improves the flash point and valeancy of the fuel. Herbie.

 

[snoman]

How old is the battery?

5 yrs old, almost to the day. It's a Bosch Silver, heavy duty, with 5 yr warranty and I've no reason to doubt its performance when it can crank a cold engine for 15 secs, or longer, without flagging.

Also, since the car was new, I have only used high cetane premium fuels, such as BP Ultimate or Shell V-Power, whenever available.

I regularly check for glowplug faults using an OBD2 code reader and have only needed to replace three since new.

 

[Taffy7hfa]

Hi Snoman, that is interesting, 30 seconds is a long long time to crank a common rail diesel, near instant starting is a characteristic of these engines, long cranking times are usually an indication of a fault, most glow plugs will reach their maximum temp in less than 6 seconds, so why strain the starter and battery unnecessarily ? I get twitchy if any of mine take longer than 4 or 5 seconds.
as you say, must be something that they have programmed into the ecu for some reason.it does seem odd though.

 

[Wighty]

5 yrs old, almost to the day. It's a Bosch Silver, heavy duty, with 5 yr warranty and I've no reason to doubt its performance when it can crank a cold engine for 15 secs, or longer, without flagging.

Also, since the car was new, I have only used high cetane premium fuels, such as BP Ultimate or Shell V-Power, whenever available.

I regularly check for glowplug faults using an OBD2 code reader and have only needed to replace three since new.

Could your glow plug relay be playing up , that is a long start time !

 

[snoman]

There doesn't appear to be a relay. The glowplug module is connected to the battery via two fusible links connected via generator and starter circuits. Although the glowplug module does have a reputation for poor reliability, I have no reason to suspect this module as otherwise I would have been aware of a fault code. The 15 secs cranking I referred to is extremely rare - maybe once in 6 months - and which I can live with. I was really just curious about the reasoning behind the warning in the Owner's Manual of up to 30 secs cranking being required in "very cold" conditions.

 

[Wighty]

This is the glow plug relay/module I am referring to . They are fairly common for owners to replace on the om642 engine . Mine started much better when I changed it last year

 

[snoman]

I might give that a try. Can't do any harm. Had you seen any fault code prior to changing?

 

[Wighty]

I might give that a try. Can't do any harm. Had you seen any fault code prior to changing?

No , there was no fault code , no warning light registered , it was taking longer to start each week . My thinking was the car was 8 years old and the part was £115 ish which I reckoned was not far above what someone would charge to look at the car .