e300 td - fuel/economy question

[mojo7676]

Recently bought a 98 e300 td, auto with 135k on the clock - mb history up to about 100k. love the car but hate filling up! I've done some trawling re fuel economy - anything between 25-35 appears to be the norm. i'm getting less than this - about 20mpg, at a steadyish motorway speed of 70. Before get anything done in terms of service etc, is there anything i should consider or, indeed, is there anything in specific i should ask the mech to look at? thanks in advance. mojo

 

[Parrot of Doom]

You should be getting an easy 35-40mpg on the motorway at around 70, so something is up. On a full tank of 70-80mph motorway driving, I get about 400 miles before the low fuel light comes on, and then about another 50 miles after that. If I slowed down a little it would easily make 40mpg.

Check for fuel leaks. Open the bonnet, near the windscreen washer bottle on the right side of the engine bay is a large aluminium intake manifold. Underneath that manifold, you'll see lots of yellowish plastic pipes - they're the fuel pipes.

Have a good feel around and underneath all those pipes for wet diesel. If theres any diesel at all, it needs seeing to right away. They're pop on-off type lines, no tools required other than small hands.

If you have any torque drivers, take the black plastic injector cover off the top of the engine (8 bolts, there are no surprises behind it). Theres a diesel return pipe that hops from injector to injector - its braided cotton, looks a bit like a clothes iron power cable. You can see it coming in to the side of the fuel filter from underneath that cover. They get old, start fraying, and before you know it you've got loads of diesel swilling around the top of your engine. Its very cheap and easy to replace.

Also, try shoving a few bottles of diesel injector cleaner through the engine. Check the air filter isn't 5 years old.

Also, what is the rpm at 70? It should be around 2300-2500 (can't remember off the top of my head). Its changing up into 5th gear, isn't it?

One job you should consider immediately is changing the gearbox fluid and filter. Its not a big job, and chances are it won't have been done on yours.

If you live in Manchester or thereabouts, feel free to pop over, I've had to do all these jobs on mine

 

[mojo7676]

Thanks for the info, Parrot.

Will check for fuel leaks - on the fuel pipes and elsewhere. Will also have a go at taking the cover thing off to check for signs of leaks on the 'braided' hose - i think the cover's s aluminium, though (?) but maybe i'm thinking of something else.

re - diesel injector cleaner - stuff you buy from car spares shops, i imagine? do you just pour that into the tank?

Planning on changing oil, oil filter, fuel filter and air filter in the next few days.

Revs and gear change - revs sound about right; does seem to change into top.

How do i do the gearbox fluid and filter? - whereabouts is the filter situated and i imagine changing the fluid is through a drain plug somewhere on the gbox? how much goes in, what kind... i usually get my VW car bits from GSF - am planning on doing the same with the MB. i'm not wonderfully handy with cars but i can do relatively easy stuff - done plugs/oil/filters etc on some of the cars i've had in the past but not really done much more.

Sincere thanks for the invitation to come over to Manchester - i might just do that, depending on how well I progress in the next few days.

I appreciate the advice - gives me a few things to do that might help out the fuel cons. - which, so far, is the *only* lousy thing about this, my very first, MB.

mojo

 

[robs-mbz]

I would be upset if my E300TD was using fuel like that! Mine does'nt seem any heavier on juice tha an old Xantia TD that I used to own, I get high 30's to mid 40's to the gallon with normal driving.

 

[mojo7676]

i'm *hoping* things will improve after engine service - i've checked all the fuel pipes etc and everything seems fine - no leaks that i can detect. air filter was a a bit dirty so changed earlier on today - no difference in the drive or running of the engine noticed but that doesn't mean much, i guess. might give it a few squirts of that injector cleaner i keep hearing about - any recommendations re brand etc appreciated.

thanks again

mojo

 

[230K]

Hi

Sorry guys i just dont believe that you regularly get mid 40's from an E300 Turbodiesel. Either that or estates are much harder on the fuel. Mine does 30 to 32 in winter and 34 to 36 in the summer driving easy. That is with 17" wheels. Take 3mpg off that for 18" AMG's

230K