1999 300Turbo Diesel Knockingor Tapping sound

[pwarwick]

Hi Can any one help me? My wifes 1999 E300 Turbo Diesel Elegence has recently developed a noise that sounds like there is a little man under the bonnet with a 13 spanner tap tap taping on the cylider head this is only on tick over, when shes driving along she sounds like a petrol engin very smooth and silent, but pull up to the lights and the little man comes out and starts tapping again, very anoying.
We were told that we needed new heater plugs, so off to the merc garage and a day later and nearly 300 quid home she comes and as she pulled up outside the front door with a big smile on her face geuss what? You got it that little man got his spanner out again and started tap tap tapping.
I'm now told it could be an injector, pump timming, the fuel and so on and on...........Any one got any ideas? has this happened to you? Please can you help us?

 

[Bazzle]

Sounds like a dribbling injector. Diesel noise can be frightening if youve never had diesels before.

Try a can of injector clean in the tank when 1/4 full.

Bazzle

 

[Parrot of Doom]

Glow plugs would make absolutely no difference whatsoever to whatever that sound is once the engine is up to temperature. Glow plugs just help the car to start from cold, nothing else.

It could be an injector or a tappet, or the timing chain, or any number of things. Its pretty impossible to diagnose an engine noise over the internet.

If its an injector you'll probably be able to feel which one it is by touching the metal injector lines that run through the intake manifold at the top of the engine. There are 6 of them, and whichever one you can feel knocking will be the culprit. Removing the plastic cover from the top of the engine can make it an easier diagnosis. You can take your car to have the injectors cleaned and tested at any number of injector specialists, you don't need to use a MB garage for that job.

As for the mercedes garage, I would ask them to explain how glow plugs could possibly make such a noise when they can't, and why you have spent £300 on a repair that would never in a million years sort the problem out. Mind you, glow plugs is a tricky job on these, and they do go at some point, so its not all bad news. Did the yellow glow plug light stay lit for a minute after the engine had started?

 

[pwarwick]

Glow Plugs

Hi Yes The Light Stayed On For A While Thats The Main Reason We Had Them Changes But The Noise Started Around The Same Time So Not Being Very Technicaly Minded We Presumed The Two Were Linked. Thanks For Your Time, We Will Start With Some Injector Cleaner Then I May Get My Local Garage To Have A Listen To It, By The Way Many People Just Say Oh Diesel They Can Make All Sorts Of Noises But I Would Love To Have It Sounding Like It Used To Bu Ti Only Have Limited Funds So Hopefully I Can Find The Fault Without Too Much Expence. Thanks A Lot
Pete

 

[Dieselman]

I echo the Parrot.
Glowplugs are only in use for a maximum of a minute from a cold start so can't cause this problem.

Now if the noise is a real humdinger of a knock which sounds like the engine is going to throw a rod then here's a little surprise.
This could well be the MAF sensor. Don't all laugh at once I've actually experienced this but only in really cold weather.
Engine at idle, bang, bang, bang. Drive the car silence.

Try this test.
With the car at idle and banging away raise the revs by pulling the accellerator potentiometer on the inner wing. As the revs rise a bit the noise quietens down.
Let the accellerator go so the revs fall back to idle and listen. If the noise stops completely as the revs drop the engine mechanicals are probably Ok. At about 800 rpm the fuel comes back on and the noise starts again. This indicates a fuelling problem, but after injector cleaning and testing there was nothing wrong.

replacement MAF soerted it.

Of course it could be something else completely..

 

[pwarwick]

E300 Knocking Sound

Cheers Dieselman I Shall Endever To Find Out What A Maf Sensor Is, Hope Its Cheapish, Fingers Crossed
Regards
Pete

 

[Gollom]

Hi Can any one help me? My wifes 1999 E300 Turbo Diesel Elegence has recently developed a noise that sounds like there is a little man under the bonnet with a 13 spanner tap tap taping on the cylider head

Could it be Ian Walker?


Pete
Sorry to hijack but I just could not resist. As you get to know us all, my comment will make sense - Ian is a MB specialist par excellance! Welcome to the forum and I'm sure someone will be able to offer advice.

 

[pwarwick]

:d Cheers

 

[GazCaff]

Did the noise appear quite suddenly or has it developed over time? I'm wondering if a large dose of injector cleaner would help.

 

[pwarwick]

E300 Knocking Noise

Hi Yes It Seemed To Come About The Time My Cold Start Plugs Were Playing Up, I Thought It Was Them So I Had Them Changed But No Change, I Shall Try A Good Dose Of Injector Cleaner. Cheers
Pete

 

[Ian B Walker]

Could it be Ian Walker?


Pete
Sorry to hijack but I just could not resist. As you get to know us all, my comment will make sense - Ian is a MB specialist par excellance! Welcome to the forum and I'm sure someone will be able to offer advice.

Dead man walking alert

Peter, welcome. I have to concur with Bazzle. I have a similar problem with a customers diesel. I asked a local Motor Engineer ( good friend actually ) and his opinion matched mine, dribbling injector. Currently running the tank dry with 2 cans of Wynns, Power Plus in the system. If that does not clear it then its injectors out and overhaul the lot.

 

[pwarwick]

1999e300td Eligance Knocking Noise

Many Thanks Ian, This Is A Very Good Site Im Very Impressed With The Response From All You Guys, A Good Dose Of Injector Fluid On The Way
Cheers

 

[bolide]

Noisy tappet, I'd say. It was very common on the earlier engines

Nick Froome
www.w124.co.uk

 

[pwarwick]

1999 E 3000 T D Knocking Noise

Hi Bolide /not Sure Its A Tappet As Its Not All Ways There Every Day. Its A Low Milage 1999 Engine, Serviced Once Or Twice A Year.
Everything Seems At The Moment To Be Pointing At A Dribbling Injector
Many Thanks

 

[Parrot of Doom]

Hi Yes The Light Stayed On For A While Thats The Main Reason We Had Them Changes But The Noise Started Around The Same Time

Ah thats ok then, they were quite right to change the glowplugs. If you do a search on here you'll find that they're a tricky proposition on these engines, and not to be undertaken lightly.

 

[Parrot of Doom]

Cheers Dieselman I Shall Endever To Find Out What A Maf Sensor Is, Hope Its Cheapish, Fingers Crossed
Regards
Pete

http://mbclub.co.uk/forums/showthread.php?t=26300

Try that first, if it doesn't work then you can buy a new insert from Bosch for about £80. Mercedes will try and sell you the insert and the pipework, which is much more expensive, but you wouldn't need anything but the insert.

IIRC the part number is written on the side of the MAF insert?

BTW, the forum software is correcting your posts as you're typing in CAPITAL LETTERS ALL THE TIME Type in lower case, its easier for us to read

 

[Parrot of Doom]

Dead man walking alert

Peter, welcome. I have to concur with Bazzle. I have a similar problem with a customers diesel. I asked a local Motor Engineer ( good friend actually ) and his opinion matched mine, dribbling injector. Currently running the tank dry with 2 cans of Wynns, Power Plus in the system. If that does not clear it then its injectors out and overhaul the lot.

Ian, have you tried this method:

http://www.mercedesshop.com/shopforum/showthread.php?t=113596

He basically unhooks the intake line to the prefilter and puts the fuel heater end of that line into a bottle of diesel purge. The return line from that bottle is one of the lines that heads into the fuel filter.

I haven't tried it myself as I don't have any piping to play with, but it looks like a very good way of chucking a load of injector cleaner through the engine in one go.

 

[Parrot of Doom]

Heres the system:

Why won't it show as an image?

He has a spare line, it looks like there are 2 lines connected to the prefilter but hes disconnected one of them and is using the spare instead.

 

[Wezzel]

Cheapest option is a good dose of injector cleaner. If it doesn't work you haven't lost much.

My car developed diesel knock and this cured it immediately. I now use it on every fillup.