e300d nasty noise at 3000rpm

[stigsblade]

I am hoping someone can help with this. The noise is a rasping mechanical vibration which comes in at 3000 revs and also if you put your foot down at other engine speeds. it is present at 3000 rpm no matter what the load. it seems to diminish at higher speeds but i cant be sure if this is determinable.
I have a 95 e300d w124, with a recond. engine fitted at 225k. in the last 12 months i have also had a lift pump, new plugs, new fuel filters seals and pipework. I have checked the airflow valve on the underside of the inlet manifold which although appears to be normal, certainly has some bearing on the problem. If you hold it shut, no noise but loads of white smoke, also engine runs very lumpy.
before i give in and go and part with some more overdraft, anyone got any ideas?

 

[Bolide]

It could be the serpentine belt damper top mount breaking up. Reach behind the fan and press the damper towards the block - if the rattling decreases the top bush is worn

There's an exhaust bracket under the gearbox that rattles if loose. On mine it rattled at exactly 2200 rpm

White smoke is not a good sign. I'd have the whole inlet manifold off and track down what's going on. The engine will run without it

Nick Froome
www.w124.co.uk

 

[stigsblade]

thanks nick

tempted just to let my guy in crewe look at it, sounds more problematic than I thought! What would the white smoke indicate do you think?

 

[Bolide]

White smoke

Check this link:

http://www.aa1car.com/library/diesel.htm

"If white smoke is still visible after the engine has warmed up, the engine may have one or more bad injectors, retarded injection timing or a worn injection pump. Low compression can also be a source of white smoke. Air in the fuel system can also cause white smoke"

If your guy in Crewe fitted the engine I'd be inclined to return it to him

Nick Froome
www.w124.co.uk

 

[stigsblade]

getting better

hi folks
Changing filter and or cleaning air flow valve has helped but noise is still there. have Problem seems to be related to the opening and closing of valves, ie that there is a slight noise up to just under 2000 revs, then a clear patch but with the engine a bit lumpy up to about 2900, then clear again after about 4000. the lumpiness seems to disappear at 2900 when the noise kicks in. Anyone know the symptoms of A. a dirty or faulty air sensor, B. vacuum pump, or as an added possibility, C. blocked injector(s). BTW As an added bonus, the engine seems to be rough idling when the car is moving but as soon as it is at a complete standstill it is ok. Possible gearbox link??