Mercedes Diesel Engines - why so many problems?

[S80]

Not having owned a single diesel-engined car in the last 30 years or so, I've been looking at the pros and cons of a modern 'oilburner'.

One thing that strikes me though - judging by the frequent posts on this site - is the number of problems occurring with relatively recent Mercedes diesel engines :neutral:

'Black death', injectors seizing or leaking, air ingress, glow plug woes - to name but a few.

Considering that Daimler-Benz have had diesel engines since the dawn of the automotive age, what's gone wrong? Did they farm the design out to some work experience types? Have other manufacturers suffered similar maladies, and it is a consequence of ever more highly-stressed designs, keen to wring the last mpg out of the engine?

 

[Danny&Andrea]

Its a widespread problem not just within the Mercedes group. Its the modern common rail which is the problem. They are in their own right fantastic engines prepared and tuned for great performance and equally economical.

The current day and age, thats what the consumer wants, powerful diesel engines.

The drawback is they are expensive to put right when faulty.

If you asked me would i buy another petrol car after having common rail TD's for last 5-6yrs? i'd probably say no everytime.

 

[Quick Silver]

Not having owned a single diesel-engined car in the last 30 years or so, I've been looking at the pros and cons of a modern 'oilburner'.

One thing that strikes me though - judging by the frequent posts on this site - is the number of problems occurring with relatively recent Mercedes diesel engines :neutral:

'Black death', injectors seizing or leaking, air ingress, glow plug woes - to name but a few.

Considering that Daimler-Benz have had diesel engines since the dawn of the automotive age, what's gone wrong? Did they farm the design out to some work experience types? Have other manufacturers suffered similar maladies, and it is a consequence of ever more highly-stressed designs, keen to wring the last mpg out of the engine?

All modern diesel engines are prone to the same thing such as black death whatever the Marque be it CDI , HDI , or Multijet usually after very high mileages .Petrol engines are now going the same way , the new E Class for example is CGI (COMPUTERISED GAS INJECTION) SO MAY SUFFER THE SAME FATE .

It gives the maximum fuel economy and performance from what would otherwise be a not very fuel efficient engine whatever your taste in cars/manufacturer.

 

[6pot]

Personally, i dont think they have more of there fair share of problems. The pros far out weigh any potential problems quiet refined efficient etc etc.

 

[grober]

The difference is that direct petrol injection engines only have a fraction of the fuel supply pressure or compression ratio of modern diesel engines. The result is that the petrols are running well within the engineering tolerances of today's material technologies. Couple that to the problems of diesel particulate filters demanded by forthcoming environmental legislation and I would hesitate to own a sophisticated modern diesel at very high mileage or out of warranty. The only down side of direct petrol injection is many demand the more expensive 98+ octane fuel to make full use of their potential.

 

[madf]

I have driven a common rail diesel for the past 4 years in stop start motoring with zeo issues. Car has now done 40k miles (no DPF tho). I use only Shell diesel and a fuel injector cleaner every two years.

Supermarket fuel is a no no in my view when dealing with modern designs.

Mercedes engineering is still not up to Japanese standards and - see injector problems on NEW Mercedes and Mercedes electronics are still questionable: see 7 speed autobox issues elsewhere..

Having said that, Mazda diesels are a definite no go being unfit for purpose in my view (DPF regeneration tends to flood the sump with diesel and bang..).. BMW appear to few issues: but then they are an engineering company living in the present.

 

[djb]

It is a Euro 4 thing,to meet the emission requirements the engineering has been pushed to the limits. Cars, trucks , all manafacturers are having faults.

 

[Rappey69]

Another reason for seeing so many diesel faults on here is that there are/is to date over 35,000 members for this site.
Would you join just to post " I have covered over X amount of miles and never had an engine fault"?
No? Neither would any others (harldy) so instead the posts are from people joining because thay have a fault and can make use of the vast availability of knowledge from other members to help diagnose problems.
Due to this would say it would be impossible to judge the percentage of cars with faults that should not be.

 

[turbopete]

tpo and bottom of the problems is that they try to make things overly complicated. take the general set up on my E300 TD. fuel comes from the tank, to a fuel heater, then to a pre filter, then down to the lift pump then up to the fuel filter, then down to the shut off valve then to the injector pump, then fuel can go via a return to the tank or from the filter to the tank if required. whats wrong with fuel going from the tank to the lift pump to the heater, to the fuel filter then the injector pump with the cut off solenoid built in? the return goes from injector pump/leak off rail straight to the tank, no connections (in most cases to) the fuel filter (like ford, vauxhall and most other manufacturers use) and why cant normal jubilee clipped hose joints be used instead of stupid push fit plastic unions with rubber o rings? i know they have got more complicated for emissions sake, but why couldnt the basic set up have been kept simple?

 

[whitenemesis]

Another reason for seeing so many diesel faults on here is that there are/is to date over 35,000 members for this site.
Would you join just to post " I have covered over X amount of miles and never had an engine fault"?
No? Neither would any others (harldy) so instead the posts are from people joining because thay have a fault and can make use of the vast availability of knowledge from other members to help diagnose problems.
Due to this would say it would be impossible to judge the percentage of cars with faults that should not be.

Hear! Hear!

Forums do NOT provide a representative sample of owners. I would guess the vast majority of MB owners have never frequented an internet forum. That is not to say that some of those owners do not suffer the same problems but to judge the frequency or percentage occurrence of a particular problem from forum postings is very misleading.

Hospitals are full of sick people but the majority of people are not sick..

 

[Xtractorfan]

Personally I think one of the major problems with modern day engines is the fact that they are now covered with a large piece of moulded plastic (sound insulated as well) and when people lift the bonnet all they can see is the relevant filler caps for oil and water...even the washer bottle filler cap is sometimes obscured or hidden away..
So in effect you never see the engine and any subsequent leaks or problems that most drivers would normally question...

I have to add a well serviced car will have very few problems.. touch wood mine hasnt given any bother over this past 2 years.. a few injector washers and a thermostat ..routine servicable items i would say

 

[br0ke]

BMW appear to <have> few issues: but then they are an engineering company living in the present.

Google swirl flaps

I had a fantastic 95 520i for 12 years. Broke down twice but never let me down - always came back to life to get me home where it got the TLC needed to keep it going. Minimum servicing costs once I stopped taking it to the dealers.

I wanted a BM diesel but after reading about their issue with swirl flaps and engine failures - and a colleague experienced this first hand - and reading about their attitude that it 'couldn't possibly be their fault' (like MB with rust or vaneo issues) I defected.

Looks like diesel engines are just more stressed now

 

[Number_Cruncher]

Common rail engines really are revolutionary.

Consider the OM606 engines made up to 1999 or so. If you showed such an engine to a mechanic working in the 1940s, the basic principles would have been familiar, the lift pump, the fuel filter, a chain driven cam, and an inline lift pump. The 1940's mechanic might raise an eyebrow at double cams, 4 valves per cylinder, an alternator rather than a dynamo, a viscous fan drive, and the resonance flaps, but, really, these are just trimmings.

The concepts and pressures involved in common rail would make the 1940s mechanic's eyes pop out!

Petrol engines have gone through their equivalent change in technology over a much longer period of time, their design rules have evolved - common rail diesels have been a sudden step change in comparison. Engineering needs a bit of time to learn, and catch up. It will catch up!

 

[S80]

Engineering needs a bit of time to learn, and catch up. It will catch up!

Fair points, N_C - but in the meantime the customers are the testbed

I don't know what the development budgets are for major car companies, but you might expect better testing of such 'revolutionary' technologies.

 

[nick73]

D'oh!! just bought a (2000, x reg) e320 cdi with 100k (full history), hope I have no problems!!:neutral:

 

[syncropaddy]

I have recently sold a late 2006 VW Passat 140TDi that I drove for 174,000 miles without missing a beat. Its a very modern and economical diesel and gave me no trouble at all. I dont travel as much now so I dont need a diesel anymore. I considered a C220CDi to replace the Passat but there were many negatives. I have a lovely collection of W124s and a W126 so I didnt replace it. But if I did need a diesel it would have a VW badge on it because they are so good - always - like MB of old

 

[teabag]

Not having owned a single diesel-engined car in the last 30 years or so, I've been looking at the pros and cons of a modern 'oilburner'.

One thing that strikes me though - judging by the frequent posts on this site - is the number of problems occurring with relatively recent Mercedes diesel engines :neutral:

'Black death', injectors seizing or leaking, air ingress, glow plug woes - to name but a few.

Considering that Daimler-Benz have had diesel engines since the dawn of the automotive age, what's gone wrong? Did they farm the design out to some work experience types? Have other manufacturers suffered similar maladies, and it is a consequence of ever more highly-stressed designs, keen to wring the last mpg out of the engine?

Over the last 15 years my wife and I have run several diesel engined cars: corsa 1.5TDi, Cavalier 1.7TDi (both Isuzu engines), Omega 2.5TDi (BMW engine), Vectra 2.2TDi (Vauxhall engine), E320CDi (Mercedes engine) in addition to the big petrol cruisers in my signature.

These cars have all been purchased at around 3 years old with between 50,000 and 70,000 miles on the clock, then ran for 3 years or 60,000 miles before being sold.

All cars have been serviced to the manufacturers recommendations and none (Diesel or Petrol) have ever suffererd what I would consider to be an "ENGINE" failure (Block,Crankshaft,Pistons,Head or Camshaft).

What I have experienced is failure of ancillary components (High pressure fuel pump, Injectors, Distributer, Damped crankshaft pulley, Belt tensioner, Water pump); These components are usually sourced by purchasing departments from suppliers outside of the parent company whose quality assurance system is not up to the standard of the designers intent.

Again I think this is a case of "Bean Counters" controlling and subsequently damaging the reputation of well intentioned motor manufacturers.

 

[Number_Cruncher]

Fair points, N_C - but in the meantime the customers are the testbed

It could be worse!

For the best part of 90 years, all customers of petrol engines were the testbed! - it was only the introduction of electronic ignition and injection, and the advent of decent oils all happening together in the mid to late 1980s which really made easy starting, reliable, economic petrol engines which could routinely be expected to exceed 100,000 miles. It's easy to forget how rubbish *all* engines used to be.

 

[47p2]

It could be worse!
It's easy to forget how rubbish *all* engines used to be.

Back in 1947 when my Rover was built it was common practise to de-coke the cylinder head every 5000 miles

 

[steve--o]

the problem is,with all thease modern cars, i think the consumer has been conned including merc owners

im a time served engineer (not prison :lol: ) but have been off my tools for 25 years but still dable.

i run a 1989 2.5 190d ,i change the oil filters 3 times a year,it delivers 38 mpg min and travels around all day at 80mph,ive had the car for 5 years,this year has been bad on the maintance front,and ive had to spend 350 quid on parts,ie water pump,hoses,pads & disc,s ,track rod end.
apart from this year ,no problems and its done 300k.

im not skint and if i wanted to could quite easly afford a 20k merc,but to be honest i wouldent as i think all modern motors are an electronic money pit / nightmere

and of course the other thing for the uk folks,whats the point in buying a super merc ,to roll around everywhere at 30 mph when thairs some twat on a speed camra nicking you who,s time would be better spent nicking crimes,bankers, MP,S

go on treat yer selfs leave yer money in the bank :lol: by a 190d
cheers
Steve a uk common sence exile now in spain :lol: