Started getting fluctuating readings on my temperature gauge over the last week. The problems originally started on my way to work whereas my drive home it was back to normal which made me think it could be due to the cold weather but it has now started playing up while the engine is warm.
Engine seems to be warming up at normal speed and gauge reaches ½, all fine (never goes above ½ so not overheating). While driving the gauge stays at 1/2 but stopping in traffic it will drop to cold or ¼. Start moving again and temp reading rises. Gauge rises and drops all the way to work (45 mins drive in traffic).
I will check to confirm but I don’t think I’m losing heat from the heaters when the gauge drops.
My limited mechanical knowledge points to two possible obvious problems
1) Temp sender faulty. Would be my first thought as the heater stays warm despite gauge reading
2) Thermostat? But wouldn’t this cause heaters to blow cold?
I’ve also noticed that the idle seems a little lumpy when cold and warm, could this be related?
If this is a temperature sender issue could this cause problems ie tricks vehicle into thinking engine is colder than it is so adjusts fuel mixture? If so is it something that needs to be fixed sooner rather than later?
Is my thinking correct? Anything I can do to help diagnose?
This is a 14 reg Transit custom 2.2 diesel
Cheers
Mark