Diesel engine noise

[axe220cdi]

Hi, I'm about to buy my first merc (e class 220 cdi) which is also my first diesel, and i'm a bit suprised at how loud the engine is. Is this normal, and is there anything i can do to reduce the rattle? My car is a 53 plate and done 60,000 miles.

 

[brandwooddixon]

I don't own a diesel myself and I'm sure that the true diesel owners will soon pipe up, but I have driven a 320CDI.

From my experience the engine was quite niosy on initial startup, much the same as any diesel, but when warm it was difficult to tell that it was a diesel.

From the inside when driving I don't recall it being any noticeably noisier than my petrol car.

Just a few questions:
Is it the typical diesel rattle or something else?
Does the engine get quieter as it warms up?
Is the noise mostly at idle?
Is it noisier inside than you expected?
Is it speed related?
If you raise the bonnet does the noise appear to emenate from the front of the engine (you may need to use the old stick/screwdriver stethescope trick) or from the injector pump and lines?

 

[jberks]

The first time I drove a 320cdi I was surprised at the noise, but then it's all relative and i was coming from an almost slient V6 petrol. After a couple of days I got used to it and later bought a 270 diesel of my own.
Mine is rattly when cold and not exactly silent when warm and accelerating, but once cruising, from the inside at least, you'd have to listen hard to hear it. At idle from the outside, it's a bit of a tractor but from the inside it's more of a quiet hum.
The 53 plate will be the old 220. The new generation 220 is a lot quieter and the V6 diesels virtually silent but we're going to have to wait for them to come down to our price bracket.

 

[st13phil]

As jberks says with the exception of the latest virtually silent V6 diesels, all of them are noisier than a petrol at idle and when accelerating. However, once cruising you have to listen hard to hear any diesel noise giveaways. Assuming that the car you're buying is quiet when cruising then there's not much you can do to decrease the noise at idle or when accelerating.

Of course, you could always stuff some of the fuel money you save in your ears to quieten it a bit

 

[axe220cdi]

Thanks chaps. Most of the noise is at start up, and being on a dealers lot for a couple of months, i don't believe anyone had seriously driven her in a while. I dident drive her long enough to see if the noise would go away once she warmed up, and didn't take her out on the motorway (the tracking was pulling to one side), but will do so befor i buy. A diesel is a diesel i guess, and as Phil says, "i can stuf my ears full of the petrol money i'll save"! Thanks again!

 

[alec2]

I have a 52 plate c class with the 220 cdi engine.

I have had the same problem since new.

The merc diesels are/were noiser than the Peugeot range and my dealer admitted this when discussing my complaint.

The problem is more pronounced when cold or running under a light throttle at low revs. Also note that the autos hold on to lower gears longer when cold to warm up the Cat quicker, this can make the engine seem noisier.

At normal cruising speeds my engine is quite quiet.

The current engines are much quieter and smoother. I believe they give "3 squirts of fuel per bang" and also have a balance shaft.

Recently I changed from TESCO fuel to SHELL and have convinced myself that the Diesel rattle is much reduced. Can this be so? Is it something to do with timing and can I optimise the timing for least noise, is ther a easy adjustment on the car?

ALEC

 

[wireman]

Don,t touch the timing, it is very critical on diesels, get it ever so slightly wrong and starting will be a nightmare along with a long term risk of crankshaft bearing and piston damage.

The 3 squirts per bang is a feature of modern advanced common rail injection systems which benifits both fuel consumption and emmissions. The more advanced emmision control systems with the latest diesel cat convertors need this type of fuel system to function correctly.

I have also switched to Shell but only because the Tosco price is higher in my parrish.

Fuels with different formulations will cause differing running characteristics but these should be quite small differences.

 

[Richard Moakes]

Hi, I'm about to buy my first merc (e class 220 cdi) which is also my first diesel, and i'm a bit suprised at how loud the engine is. Is this normal, and is there anything i can do to reduce the rattle? My car is a 53 plate and done 60,000 miles.

Get a petrol one ?

Sorry, couldn't resist it, I don't like diesels very much

 

[euclidb2]

Hi, I'm about to buy my first merc (e class 220 cdi) which is also my first diesel, and i'm a bit suprised at how loud the engine is. Is this normal, and is there anything i can do to reduce the rattle? My car is a 53 plate and done 60,000 miles.

If coming from a petrol the noise will be noticeable immediately,more so in cold weather as will fuel consumption,but as speed gathers and the engine warms up it will become a lot quieter,and at 50 mph+ (with trans in top)it will become unnoticeable.My 53 reg E220 auto will happily return 40-50mpg running about locally(depending on traffic)and 55mpg on a run at 60-70mph.The fuel consumption compared to a petrol,probably 10-15 mpg,does compensate for the noisier diesel,and you could always keep some earplugs in the ashtray!.Also if an auto,i find the auto box is better suited to a diesel than petrol,lots of low down torque,i also find using Shell or other premium brands of fuel seem to run quieter than City Diesel offered by supermarkets,or is just me?

 

[jberks]

i just turn the radio up a bit.

 

[euclidb2]

i just turn the radio up a bit.

got plenty of earplugs if ye want some,bright yellow ones.

 

[axe220cdi]

Stethescope trick?

When asking about Diesel rattle at the beggining of this thread, someone said:

"Lift the bonnet and you may need to use the old stick/screwdriver stethescope trick".

Can someone please ellaborate?

 

[liverbird]

Placing the blade of the screwdriver on the engine and press your ear against the handle and listen?

 

[axe220cdi]

I guessed as much, but what am i listening for?

 

[axe220cdi]

I don't own a diesel myself and I'm sure that the true diesel owners will soon pipe up, but I have driven a 320CDI.

From my experience the engine was quite niosy on initial startup, much the same as any diesel, but when warm it was difficult to tell that it was a diesel.

From the inside when driving I don't recall it being any noticeably noisier than my petrol car.

Just a few questions:
Is it the typical diesel rattle or something else?
Does the engine get quieter as it warms up?
Is the noise mostly at idle?
Is it noisier inside than you expected?
Is it speed related?
If you raise the bonnet does the noise appear to emenate from the front of the engine (you may need to use the old stick/screwdriver stethescope trick) or from the injector pump and lines?

Hi Chris,
Further to my 'Diesel Noise question' could you please elaborate on your responce: "you may need to use the old stick/screwdriver stethescope trick" ?
What am i listening for?

 

[brandwooddixon]

When I originally posted I didn't take in that you were looking at a car to buy on a forecourt. Probably because I'd only had 4 hours sleep.

The screwdriver trick (actually almost any metal rod will work) allows you to more easily pinpoint the source of any noisies generated from within engine components. You place one end on the component and listen at the other - noises will be transmitted up the screwdriver to your ear.

For example excessive noise can be generated by a worn timing chain and/or tensioner, which is buried away in the front of the engine.

Rereading your post it sounds to me as if the vehicle that you were trying out just needed a good run to get warm and the oil flowing. Even my V8 petrol sounds noise initially if it's sat for a few week or so.

 

[len_merclover]

i prefer the diesel as with big cars like the e class it gives it some presence!

 

[axe220cdi]

Thanks chaps, you've been of great help. I cant wait to pick her up at the end of the month!

 

[grufflybear]

Just wanted to concur with general view that engine can be noisier when cold but soon warms up and when running it is very quiet. I have been running it on Shell V-power diesel (Shell's premium diesel) and I am convinced that after using this fuel for a couple of weeks the engine was quieter at idle too... ok it costs a bit more but unless you are doing a very high mileage and the cost is that critical it is worth a try.