Poor diesel economy

[Mr Lawrence]

Ha ha ha I don't think so!!!

Spirited drive on A & B roads.

[KEN33Y]

Towards the end of last year I averaged 54mpg on A & B Roads in the car I use for work and I was on a round trip of 130 miles daily and believe me my foot was to the floor wherever I deemed it safe to do so around the Brecon Beacons and Market Towns such as Hay-on-Wye, Leominster and the retrospective villages associated with them. The car is a 55 plate Mercedes CLK270 Cdi and moves so the figure shown on your picture not not surprise me.

[Old Peter]

I looked at the trip computer today and find that on my last tankful of Shell Vitro I have done 434 miles and have still got 117 miles left in the tank.  That is not bad for a tankful!

 

Peter.

[Raistlin]

My S Type had an average fuel consumption of 38MPG recorded on the trip computer when I bought her but since I zeroed it, my best is 29MPG. Maybe it will increment slowly over time :)

 

Mind you, I also note that the coolant temp doesn't get to optimal by the time I get to work, a journey of some 10 miles mostly at 60 to 70 mph, so, even allowing for the sheer size of the engine, I might have to consider looking at the operation of the thermostat.

 

As an adjunct, I use bog standard Sainsburys diesel rather than the branded stuff. Some say that it makes a difference. Also, I used to use Millers Power Plus additive in my fuel when I had my Rover 75 diesel. Does anybody use that in their S Type and does it make a difference please?

[Old Peter]

Hi Paul,

 

I find that my engine takes about 12 miles to get to normal operating temperature in the morning.  To assist the heating of the cabin there is an auxiliary heater on the S Type which lets the engine get on with the business of getting up to normal temperature.

 

I find I get a better mpg using Shell Vitro than Supermarket fuel, but over the past there have been bee quite a few members who have used the bog standard fuel with a Millers additive, with good results.  My nearest supermarket petrol station is 4 miles away and my Shell Garage is 450 yards, which does have a bearing on where I fill up.

 

I also had my car Terracleaned which also made a difference to performance as well as mpg.

 

Regards,

 

Peter.

[Raistlin]

"To assist the heating of the cabin there is an auxiliary heater on the S Type which lets the engine get on with the business of getting up to normal temperature."

 

Ah. What indication is there of that heater functioning please? Presumably it is automatically switched on and off?

 

I wonder whether that's why I occasionally get the faintest whiff of AvTur (ie burning kerosine) sometimes when I start the car if I don't move off immediately?

[Mr Lawrence]

The burning smell you get is the heater working.

This time of year it shouldn't be working.

Also, you'll get that heart stopping moment when smoke pours out of your near side wing making it look like your cars on fire!!!

This, apparently is "normal"

[Old Peter]

Hi Paul, 

 

That is why you get an early whiff of fuel when you start off.  It automatically switches on and off.

 

It probably is not on for very long.

 

Regards,

 

Peter. 

[Raistlin]

The burning smell you get is the heater working.

This time of year it shouldn't be working.

Also, you'll get that heart stopping moment when smoke pours out of your near side wing making it look like your cars on fire!!!

This, apparently is "normal"

 

 

Much like the FBH on the Rover 75 then :) That also used to sound like a 747 taking off as well.

 

 

Hmm... should be able to arrange the cabin heater to run for a period of time before the car is required so warm to get in to when the weather is cold ;)

 

Does the heater sound somewhat like a turbo running, if, for example you switch the engine off only shortly after starting it?

[Raistlin]

It's not diesel as in exhaust fumes Jim. It's rather like burning paraffin, or AvTur, as I describe it :)

[Raistlin]

OK, this morning was sub zero when I started the car and boy was it foggy... INSIDE the car :)

 

Recirculation on dealt with that.

 

What a spectacular display of white fumes.

 

I was able to get out and spot the fumes coming from the aux heater exhaust so that is definitely the cause.

[Raistlin]

Further to this, I understand that here was a modification, free to original owners, which stopped the production of the clouds of white fumes from the aux heater.

 

Does anybody know anything about it please?

[Old Peter]

Hi Paul,

 

I don't get and white fumes at all. Just a slight smell for about 5 seconds.

 

However, looking at the service history and ownership, I find that my car was owned by Stratton for a month before being sold, and that owner had the car for two and a bit years when it was bought by Stratstone who kept the car for about 4 months, during which time it had a new engine under warranty by Jaguar [either an Oil pump failure or wrong fuel].  It is a strong possibility that any modification need to rectify the auxiliary heater problem, could have been done then.

 

Regards,

 

Peter. 

[Raistlin]

I rather suspect that the white fumes were a result of damp exhaust gas combined with a particularly cold day Peter.

 

I am aware that there was a modification carried out by Jaguar but I can't dig up any info on it :(