C250 Td funny noise

[rpneed]

Has anyone had this before please, its driving me mad.

The car drives and sounds fine while its going along, but on deceleration and at low revs (1000-1200rpm), the engine sounds like its chewing nuts and bolts - for want of a better description. It goes away after a few seconds. Also on tick over, you hear the odd knock, every second or two like pre-ignition.
The engine is also pinking on acceleration, as the turbo cuts in. I've never known that on a diesel but there you go.

Any advice or suggestions i would be grateful for.

 

[Dieselman]

Probably just worn out engine mounts or a dribbling injector.

 

[rpneed]

Would a dribbling injector cause the knocking on tick over? What about the pinking, could that be injectors too?

 

[JonathanC250]

http://www.mbclub.co.uk/forums/engine/94650-c250-td-injection-hoses-issue.html

Hi there, Please see the above link to one of my threads.

I have a video on there of the noise my car is making, ( post 12)

i would be interested in knowing whether thats the noise you mean? Also if you manage to cure it.
It is also driving me mad!!
It should not sound like that! even though it is diesel!

I am looking at trying to find somewhere that will recondition my injectors, So hopefully that might stop it

Regards
Jon

 

[rpneed]

Yes thats pretty much the same noise, only mine sounds worse.
I have recently changed all pipes and seals as you did. There is no air getting in now and its running well - but still the noise.
I have spoken to a friend tonight who came up with a possibility. He seemed to think i may have a leaking injector(s) (as pointed out by dieselman). Its dripping fuel in on an intake stroke which is pre-igniting on compression causing the knocking sound. Also, if the injector isn't sealing, it will allow air to be pushed in from the cylinder to the fuel system.
I'm going to look at getting the injectors re-cond - it seems like a good guess to me. I'm told to expect about £20 per injector.

 

[Dieselman]

Have you tried a strong dose of injector cleaner?

 

[JonathanC250]

Good luck for finding someone to do your injectors for that price, i have found a few places, but they are around the £45 + Vat per injector!

It would be interesting to compare what is actually carried out by different places, and what a good reconditon should involve.

So i need to save a bit more as I want all 5 done!


Once that noise has been sorted, the car will be great again!!

Anyway, best of luck!

Regards
Jon

 

[rpneed]

I think that price was if you take the injector out yourself - not sure...

Yes, good with that Jon.

Regarding the comment from dieselman about injector cleaner, that maybe a good first option. The car sounded much worse when i first had it (about 5 wks ago) and i run 20 ltrs of kerosene through it which is the main ingredient in injector cleaner and it improved it somewhat. I may try some more.
Any ideas on a good quality injector cleaner - wynns or stp??

 

[trapperjohn]

Forte is top notch stuff. Millers also do some.

 

[rpneed]

thanks trapperjohn. would you recommend filling the filter up with it or putting it straight in the tank with the fuel?

 

[trapperjohn]

Either way is good. If you are having te filter off anyway then fill the filter. Otherwise just bung it in the tank. Good Luck

 

[rpneed]

cheers for that john - will give it a go.

 

[JonathanC250]

for best results i would get a new fuel filter, (for what they cost)

& fill it with the Forte Diesel stuff. Will be the strongest dose!

Although that didnt work for me! I think mine are just worn out, The car is on 166k now, on what i can only imagine are the original injectors!

Ive tried all sorts of cleaners, none have stoped the noise!

Millers is a good one (eco plus or power plus they keep changing the name! ), although its quite expensive, does seem to make the car a little better to respond and smoother etc.

Redex, in my opinion, has no effect

There are people on here who swear by putting a litre of ATF into a full tank to clear out the diesel system.
Am yet to try this one!

Regards
Jon

 

[rpneed]

I assume by ATF you mean automatic transmission fluid?

If so, i have heard of this before. There are apparently additives in it that work well with fuel faults.
Could be worth a bash. I got plenty of that lying around.

Good luck
Rob

 

[Dieselman]

If you take the injectors out, most diesel centres will perform a free test. You need new heat shields on refitting.

 

[SilverSaloon]

this stuff is very good.

LIQUI MOLY diesel complete system cleaner purge 1 LITRE on eBay (end time 24-Mar-11 12:03:20 GMT)

run direct from a bottle of it, with both in and out fuel pipes - and run the car until its used it all up.

YouTube - The Diesel Purge Process On A 82 Mercedes 300SD Part 1

 

[JonathanC250]

I found that stuff in a search a year or two ago, got raving reviews.

But i couldnt find anyone selling it in the UK.

Thanks for the link!

 

[rpneed]

thanks silversaloon, will definately consider that.

 

[rpneed]

Just a quick question to any of you, have you heard of problems with faulty fuel senders on the c250? I was messing with the car last weekend and it ran out of fuel, yet the gauge was showing quarter tank. Is this a common fault?

 

[Sp!ke]

Are you sure the noise isn't down vibration of some sort?

Belt tensioner damper or engine mount?

Spend 5 quid on a mechanics stethoscope and isolate the source before going any further.