On 10 jul, 02:17, D7666  wrote:
> On Jul 10, 12:54 am, Tony Polson  wrote:
>
> > Some older diesels had a cold start knob that gave a richer mixture.
>
> Ummm ... richer mixture ?
>
> Diesels have fuel injection pumps and no variable control over air -
> well at least thats how all the diesel engines I worked on are, and
> all those I am aware of now. (Turbos alter pressure, not mixture.)
>
> All cold start devices I knew of on Leyland or Ford or Cummins diesels
> were a pre-heater device that heated the fuel before entering the
> injection pump - diesel fuel tends to gel around zero deg C. Any
> exhaust clag is due to incorrect combustion where the fuel is still
> too cold, not due to a device working.
>
> And I've never come across any reference to altering air:fuel mix on
> any modern rail traction engine. Quite the reverse - modern electronic
> controls precisely maintain a constant value.
>

I had many cummins engined trucks in the seventies, cold start was by
KiGas pump to hand inject a small measured  quantity of ether (easy
start) into the injection manifold. There were no diesel volume
enhancement.
NM