Huge white smoke even at full temperature.

[Dr B]

Hi, I’ll make it short and sweet hopefully.
2008 2.0D d420t ( or something very similar)
Running ok usually for a high mileage diesel.
-Started the car, notice a bit of white smoke as usual form a cold start.
-I drove to work and noticed 2 cars flashing me over the thick white smoke. I was 10 miles into the journey. Cos it was dark I didn’t realise it was bad. I pulled in and just let it get to full temp thinking this is cold weather related. Drove away and it persisted. It won’t dev past 3000 , kinda of like limp
Mode but just generally underpowered. No warning lights, plugged into Vida and scanned. Nothing unusual. Minor electrical gremlins nothing suspicious.

I’m thinking injectors or maybe head gasket. I’ve had a car loose time by a tooth and it acted the same but chances of that are slim to none. Also notice the previous owner put fuel additive in. A full litre in the tank. I’m thinking the fuel additive may have bunked up the fuel system as this started happening when I was low on diesel now it could be running a lot of the additive.

There’s 498,000 miles. I would like to make the half a million. Thanks for your help guys and gals. Any input my joy appreciated. Dan

[Teddy1975]

Did it look similar to this? https://www.youtube.com/watch?v=vvojVf77m_E

That turned out to be the auxillary heater which runs on diesel and helps bring the coolant up to operating temps in cold weather.

[john.wigley]

That's some mileage, Doctor. 'Teddy1975' makes a good point, but I don't think, that unlike Nordic models, a diesel pre-heater was fitted as standard on cars destined for temperate climes - maybe yours does?

A compression test, if low on one, or between two adjacent cylinders, may add weight to your suspicion that the H.G. may be the root of the problem, but I would expect the cooling system to be pressurised as well if that was the case.

I can't really comment on the effect of a fuel additive as I have never used one - sorry.

Regards, John.

[wynnj]

Head Gasket would be my first thought too, but with that amount of white 'smoke' I would also expect the coolant level to be falling; have you checked?