strange behaviour at 60mph

[simon_wall69]

Fixed the problems on the new w124 e300 td and given it new filters and oil, took it out for a test drive and I've noticed something new...

Between 55 and 60mph the engine doesn't seem to run smoothly, almost as if the engine is missing. At every other speed it seems fine. I even took it over 100 on the motorway and it pulled fine at this speed. But slowed down again and between 55 and 60 the car still seemed to miss.

Any ideas what this could be? Normally, it runs and pulls as it should. The car has done 173,000 miles.

 

[television]

As that would indicate a miss a around 2800 if you take it out and lock the box into 2nd or 3rd see if it does it when you get to 2800 and up RPM

 

[Bolide]

I think it's one of the vacuum-operated butterfly valves in the inlet manifold oscillating. I've had this on an E300 Diesel before

If you can reproduce it at the same revs in 3rd then park up, rev the car in Park and watch to see if the engine hunts at 2800 rpm. Watch the EGR actuator when you do this

I don't know which butterfly it is (there's one half way over the crosspipe and on in the middle of the crosspipe on the righthand side) but I suspect that's the problem

You may be able to solve it by removing & cleaning the butterfly & actuator

Nick Froome
www.w124.co.uk

 

[simon_wall69]

Many thanks, sounds very plausible - I'll have a look today if the weather is ok.

 

[simon_wall69]

Went out in it again and the problem seems to have expanded. Looked under the bonnet and I noticed that there is a bar that runs across the top of the engine from the throttle lever (number 7 on the diagram.) to some sort of valve connected to the air intake, by the filter. When I increased the engine revs at idle, this seemed to oscillate; could this be the problem?

 

[simon_wall69]

http://www.detali.ru/cat/MB/B01005000025.0136.gif

Sorry, this diagram, I can't seem to find one with the right part on it.

 

[television]

This is the link for the non turb cars sold in the UK

http://www.detali.ru/cat/oem_mb2.as...GM=717.433&CT=M&cat=503&SID=07&SGR=180&SGN=06

 

[Bolide]

Went out in it again and the problem seems to have expanded. Looked under the bonnet and I noticed that there is a bar that runs across the top of the engine from the throttle lever (number 7 on the diagram.) to some sort of valve connected to the air intake, by the filter. When I increased the engine revs at idle, this seemed to oscillate; could this be the problem?

That's the EGR pulsing in & out. IIRC there's a modified part to stop the oscillation. I was going to try a fairly tight restrictor in the vacuum pipe to see if that would do the trick

I'd start by removing the crosspipe, inlet manifold & EGR assembly, removing the butterfly assemblies and de-gunging the whole lot

Don't drop anything down the inlet tracts

Nick Froome
www.w124.co.uk