About six weeks ago we took delivery of two new vehicles an Man 18320 Rigid and an MAN 18430 4x2 unit. The problem is that the rigid is returning aprox 15 mpg while the unit is only averageing about 7.5 mpg Now both vehicles are fully automatic and are both driven in exactly the same manner. The rigid is plated at 18 ton and the unit at 32 ton but rarely carries more than 28 ton.
The unit had a diesel leak an injector where it meets the cylinder head which was sorted by MAN ERF and as far as im aware is no longer leaking, the unit does not have any air kit (gaffer trying to save money ) and with the 5th wheel in its closest position the trailer is still a good five feet from the cab, which i have told the gaffer is not good for fuel consumption but he is under the impression that it does not make that much difference
The reason I ask is, that the finger pointing has started and i am now under suspicion for stealing diesel, which as you can imagine i am non to pleased about.
what u gotta ask yourself are you stealing diesel if not then dont worry about if he implys such as thing then take advice from ie t&g or some one like that
Dave K:
About six weeks ago we took delivery of two new vehicles an Man 18320 Rigid and an MAN 18430 4x2 unit. The problem is that the rigid is returning aprox 15 mpg while the unit is only averageing about 7.5 mpg Now both vehicles are fully automatic and are both driven in exactly the same manner. The rigid is plated at 18 ton and the unit at 32 ton but rarely carries more than 28 ton.
The unit had a diesel leak an injector where it meets the cylinder head which was sorted by MAN ERF and as far as im aware is no longer leaking, the unit does not have any air kit (gaffer trying to save money ) and with the 5th wheel in its closest position the trailer is still a good five feet from the cab, which i have told the gaffer is not good for fuel consumption but he is under the impression that it does not make that much difference
The reason I ask is, that the finger pointing has started and i am now under suspicion for stealing diesel, which as you can imagine i am non to pleased about.
Any help/advice appreciated.
Firstly engine size will have a big influence on the MPG figures, the rigid will be a six or eight litre unit and the tractor a twelve litre or thereabouts, so with the tractor more fuel is used due to larger CC of engine. No engine will produce its optimum MPG straight from new, all take time to bed in before you get max MPG, its usually somewhere between 2 and 5k before they settle down, but that will vary from motor to motor.
What environment are they being driven in, predominantly urban will always produce less MPG than a motor sat at 56 on the limiter in the middle of the green zone for extended periods. Driving style will also influence MPG. 7.5 MPG is a little on the low side for a 420 unit, I would expect to average 8.5 - 9 overall at best.
The reason I ask is, that the finger pointing has started and i am now under suspicion for stealing diesel, which as you can imagine i am non to pleased about.
I wouldnt have that mate, put up or shut up it has to be.
Phil
CM:
What environment are they being driven in, predominantly urban will always produce less MPG than a motor sat at 56 on the limiter in the middle of the green zone for extended periods. Driving style will also influence MPG. 7.5 MPG is a little on the low side for a 420 unit, I would expect to average 8.5 - 9 overall at best.
The rigid is mainly town work and the unit mainly motorways, we also have a Merc Axor 400hp which is returning 12.5 mpg so i would of expected the MAN to be similar
What trailers is it pulling,curtainsiders,boxes,flatsā¦etc?
If itās pulling curtainsiders or boxes,then with no air kit,Iām not surprised the fuel figures are low,but if itās only pulling flats,then I would agree,that with the engine being new,itāll still be a little tight,and will take a while to loosen off.
CM:
What environment are they being driven in, predominantly urban will always produce less MPG than a motor sat at 56 on the limiter in the middle of the green zone for extended periods. Driving style will also influence MPG. 7.5 MPG is a little on the low side for a 420 unit, I would expect to average 8.5 - 9 overall at best.
The rigid is mainly town work and the unit mainly motorways, we also have a Merc Axor 400hp which is returning 12.5 mpg so i would of expected the MAN to be similar
12.5 is impressive for an Axor if that is a regular average. I would still say 8.5 - 9.5 is good annual average when taking into account all driving conditions.
So youāve an artic weighing 50% more than the rigid with a far greater wind resistance and a larger engine, spending more time going up hills and your boss is so stupid he canāt work out why itās using more fuel?
Also unless both vehicles are being driven by the same driver in the same manner on the same types of road, any comparison is completely meaningless.
I have a unit that is running at 44,000 85% of the total mileage it does.
Iām currently averaging around 7.4 - 7.6 mpg
The unit has done 50,000 miles and is an auto similar to yours
So if you are only averaging 7.5 mpg @ 28,000 then there is somthing drastically wrong.
The gap between unit and trailer has been shown to be one of the major factors in poor fuel consumption but even with the excessive gap that you have those figures still arnāt right
Take it to an independant rolling road and test it (Feathers of Bradford would the best place to start) Thatāll show up any abnormalities.
One thing which came to my mind is an air leak somewhere along engines āair intakeā. We had such leak in one FH12 in itās intercooler and after intercooler was replaced fuel consumption reduced much. Pulling power also came back to the normal level.
I think the gap between cab and trailer is also one big thing to increase consumption. We have one regular 650 km long collection route and about half of it is driven empty. At summer it was driven with rigid and average consumption was around 26 litre per 100 km. At Wednesday I drove same route again but this time I had a-frame trailer with me and there is about 1.5 meter gab between this truck and trailer. Fuel consumption was around 40 litre per 100 km which is few litres more than at summer. Laden weight with rigid was approximately 17 tonnes and with trailer laden weight was around 37 tonnes. In both cases truck was the same 420 hp FH12 but with manual gearbox. Consumption increase is huge but so is also the gap between truck and trailer. Consumption is also a bit on the high side but this trailer isnāt most āeasy rollingā so it requires little bit more fuel.
Dave K:
About six weeks ago we took delivery of two new vehicles an Man 18320 Rigid and an MAN 18430 4x2 unit. The problem is that the rigid is returning aprox 15 mpg while the unit is only averageing about 7.5 mpg Now both vehicles are fully automatic and are both driven in exactly the same manner. The rigid is plated at 18 ton and the unit at 32 ton but rarely carries more than 28 ton.
The unit had a diesel leak an injector where it meets the cylinder head which was sorted by MAN ERF and as far as im aware is no longer leaking, the unit does not have any air kit (gaffer trying to save money ) and with the 5th wheel in its closest position the trailer is still a good five feet from the cab, which i have told the gaffer is not good for fuel consumption but he is under the impression that it does not make that much difference
The reason I ask is, that the finger pointing has started and i am now under suspicion for stealing diesel, which as you can imagine i am non to pleased about.
Any help/advice appreciated.
leave artic at the yard and take the rigid out and the diesel that should even things up a bit (joke)
you should tell your boss to take it back to the dealer and get it fixed, there is something wrong with it - perhaps an engine inbalance or something, maybe a turbo fault but there is definately something wrong.
difficult to comment really, i get 10+mpg out of an old erf running between 40 and 44t day in day out, if i had something that was only doing 7.5mpg itād be up for sale sharpish! theres got to be a problem somewhere, running at such low weights it should be doing the max possible which iād have thought was 10mpg minimum, is it one of these that can be put in manual to test out?
The vehicle went to the dealer yesterday to be looked at and no fault was found, not that they gave it much of a looking at, they connected it to a lap top and found no fault codes, then lifted the cab and had a glance around and that was about it. They did say that the gaffer was being a bit to quick, expecting it to perform to its max this soon and said to give it another month or so and also think about having an air kit fitted.
north surrey haulage:
I have a unit that is running at 44,000 85% of the total mileage it does.
Iām currently averaging around 7.4 - 7.6 mpg
The unit has done 50,000 miles and is an auto similar to yours.
You make feel a whole lot better, my Premium is currently averaging around 7.8mpg, it has just over 50000kās on the clock , and is running between 38-44 ton about 75% of the time, also all the trailers i pull are over 14ā10" up to 15ā3", and i think this makes no end of difference. The premium I had before this was on an 02 plate, and that was averaging around 8.5mpg, but it was pulling a 13ā2" fridge 50-60% of the time, and high trailers the rest
Mt bosses would be happy if my truck was achieving that.
Its a 54 plate fm 420, just done 180000km we run at 44tonnes half the time. It was averagng 5.9, but has recently dropped to 5.3 due to alot of work in town
Well its earning me Ā£10 month in shell pluspoints
Just got in after a Night trip to Brighton, via Grantham and Bishops Stortford so all A road/Motorway, 690km round trip, Volve FM12 420, average mpg 8.2.
Now both vehicles are fully automatic and are both driven in exactly the same manner. The rigid is plated at 18 ton and the unit at 32 ton but rarely carries more than 28 ton.
) and with the 5th wheel in its closest position the trailer is still a good five feet from the cab, which i have told the gaffer is not good for fuel consumption but he is under the impression that it does not make that much difference 
