W211 V6 Diesel

[mbenz1]

Before you make any damning diagnosis, you've got to give it a fair go!

As a previous poster has said, give it a go up the motorway when its warmed up properly and reset the fuel meter just before you get on.

Drive at a steady speed for a few miles and see what you get.

Now reset it again, and try some hard acceleration Watch the reading plummet!

If you come to a hill try and coast down it (reseting the meter before you do). Watch how you can achieve stellar economy!

I suppose my point is that stop start traffic with a cold engine for short distance journeys will give bad mpg as consumption under these conditions is terrible. A longer journey with less stop start will get the average up. On mine it needs a 2 hour journey to give me what I would believe to be a representative figure of consumption at steady state. Remember the meter gives you an average, not an instantaneous figure. To get instantaneous you need to reset the meter so it starts again and so is averaging over fewer samples. And then keep resetting it.

If this still gives unacceptable figures, then there is a problem.
If it doesn't, then your typical journey profile is just not suited to getting maximum mpg from this car.

Sorry if I've missed the point and you've already done all this, but with big cars, and small journeys, small differences in conditions make a huge difference in my experience, so you just need to be happy that your test conditions are fair!

I appreciate what you have said but the reason we bought this car was due to good fuel consumption. As a normal buyer, we looked at the fuel consumption figures and were impressed by them, else there was no reason to buy a diesel over a petrol.

The things you have mentioned in regard to resetting the fuel meter..This has been tried in the past at various driving situations but it doesn't seem to make much of a difference. At the end of the day, the engine should deploy its stated figures

Other members on this forum can achieve 30+ mpg in heavy traffic situations, so this is why it has become a concern to me.

 

[Geez1000]

On my 57 plate E320cdi estate, on a school run in slow traffic I get around 22-23 mpg this time of year. In the summer it increases to about 26mpg. On a motorway run at 70mph about 39mpg.

 

[mbenz1]

On my 57 plate E320cdi estate, on a school run in slow traffic I get around 22-23 mpg this time of year. In the summer it increases to about 26mpg. On a motorway run at 70mph about 39mpg.

Considering your merc is a 320 CDI Estate, it will do less mpg than a 280 CDI saloon. We get around 26 mpg in summer weather BUT very rear. It likes the 23mpg value for some reason. Should the weather conditions even effect the fuel consumption? This never used to be the case in our previous W203 C200 Komp Facelift

I'm now starting to think whether a 280 V6 petrol would have been a better buy - considering that gets around 21mpg in town, not much far to what the 280 CDI is returning and the refinement/smoothness of those V6 petrol engines can't be beaten.

 

[V12]

All cars suffer worse mpg during winter. Diesels are more prone to this.

If you can't get more than 23mpg from the diesel, then you won't get anywhere near 20mpg from a petrol V6 doing the same driving.

What figures were you expecting? Late 20s is realistic for town driving but there are too many variables to draw an accurate comparison.

Once you've done a tank to tank test we can establish if there is a fault with the vehicle or not.

 

[mbenz1]

All cars suffer worse mpg during winter. Diesels are more prone to this.

If you can't get more than 23mpg from the diesel, then you won't get anywhere near 20mpg from a petrol V6 doing the same driving.

What figures were you expecting? Late 20s is realistic for town driving but there are too many variables to draw an accurate comparison.

Once you've done a tank to tank test we can establish if there is a fault with the vehicle or not.

We are expecting late 20's as its a diesel engine.

I am fully certain that the tank-to-tank check would give the same as I got last time - ~400 miles from a full tank. Since the car has been serviced, its been returning a similar mpg return before it was serviced. So here, we can assume that the miles from a full tank would be the same as the previous result - 400miles.

On average, many people get around mid 20's in their 320 petrol engines, from Google searches. So surely, the 280V6 should perform even better

 

[ivandraganov]

Hi all

Getting really annoyed now..

My father’s E280 CDI has been serviced a few weeks ago but still has a few problems, which I though would be eradicated after a service.

Average mpg is still at 22. After start, it stays around late 20’s (for a few minutes) but once on the main road (stop and go driving) it eventually decreases to early 20’s due to idling. If driving at constant speed, it increases but not fast enough to keep it at the late 20's mark, which is the correct mpg for this engine

Minor jolts can be felt just before braking to 0 mph – not all the time though. I assume thats to do with the gearbox?

Tapping / Diesel engine noises can be heard inside the cabin – quieter when engine is warm

We have done the following:
- Injector cleaners (around 3 bottles so far)
- Always used premium diesel fuel – first we used BP Ultimate but now use Shell v-power
- Local Merc approved specialist STAR diag. check – 02 sensor and glow plug relay replaced (brand-new genuine parts)
- Recent service using genuine MB parts and Mobil Oil
- ‘Italian’ tune-up – recommended previously on here

All these have made a noticeable difference but symptoms still exist – the car runs fine with fast acceleration and correct gear changes – no warning lights or messages and the engine/turbo has no odd sounds from outside. Suggestions and comments appreciated.

Steve what do you recon?

 

[mbenz1]

Steve what do you recon?

In await of Steve's reply...Do faulty MAF sensors show-up codes on the ECU unit - START check, by any chance?

 

[ivandraganov]

In await of Steve's reply...Do faulty MAF sensors show-up codes on the ECU unit - START check, by any chance?

Not necessarily,I cannot be useful here because never owned W211 V6 CDI ,but Steve has one.He will answer shortly.

 

[mbenz1]

okidoki

 

[Sveina]

The consumption figures many of you guys are showing are terrible, my 07 E320 CDI 4matic with the 5 speed uses 41 imp mpg on a long trip over the mountains in Norway, the temperature was between minus 20-29 degrees celcius. The car weighs 1980 kg with full tank, without any people or luggage in it. Many of your cars should use less I think, I can never make mine use that much even when I drive reclessly...

 

[V12]

On average, many people get around mid 20's in their 320 petrol engines, from Google searches. So surely, the 280V6 should perform even better

Don't believe what you read on the internet.

 

[mbenz1]

Don't believe what you read on the internet.

To be honest, I got that info from mb forums.

 

[V12]

There are many claims made on this and other forums which don't have enough background/context to make proper sense of.

I can get over 50mpg on the motorway on a very good day but In real life I normally get just over 40mpg on the motorway.

People have a tendancy to quote their peak or max figures and they quite often take the OBC as gospel...in some case it can be wildly out.

 

[mbenz1]

There are many claims made on this and other forums which don't have enough background/context to make proper sense of.

I can get over 50mpg on the motorway on a very good day but In real life I normally get just over 40mpg on the motorway.

People have a tendancy to quote their peak or max figures and they quite often take the OBC as gospel...in some case it can be wildly out.

They sure do in some cases... Back to the original point now...

If we leave the mpg subject to one side...

What are the possibilities to get rid of engine / tapping noises and vibrations in the cabin.

When cold, the vibration on the cabin floor is very strong (especially when moving from standstill). Surely not acceptable in a Mercedes. I have had the mounts checked at local indie and no problems reported. Vibrations are still present when the engine is warm as well.

Appreciate all your help

 

[st4]

if the tapping noise is loud, it could be the front engine bearings gone

 

[mbenz1]

if the tapping noise is loud, it could be the front engine bearings gone

What is the function of a engine bearing and is there any way to detect if they are gone? Is it a expensive job?

The tapping noise is loud when cold and that's expected on a diesel, but when warm, it can be heard but at low volume.

***, I remember that you had a 320 CDI V6 as well? How did it sound in the cabin, was it just a smooth 1-tone sound (I know these engines sound gruff when hard foot is put on) or were there other sounds from the engine as well?

 

[st4]

It was very refined with practically no vibrations felt in the car. If there are loud noises, the car ain't right. Gruff sounding at full rpm but no adverse vibrations or noise. Quiet engine

 

[mbenz1]

It was very refined with practically no vibrations felt in the car. If there are loud noises, the car ain't right. Gruff sounding at full rpm but no adverse vibrations or noise. Quiet engine

That description is what I expected of our CDI. Any idea how much it is to replace engine bearings if they are at fault?

 

[mbenz1]

I noticed a slight ticking sound from the engine, near the front left tyre area of the engine. I seen in some other threads that this noise could be bearings ticking after a service. The service was done a few weeks ago on the car. Worth giving the company who carried out the service a phone call?

 

[mbenz1]

BUMP..

I noticed a slight ticking sound from the engine (outside), near the front left tyre area of the engine. I seen in some other threads that this noise could be bearings ticking after a service. The service was done a few weeks ago on the car. Worth giving the company who carried out the service a phone call?