E300 Diesel White Smoke and Jerking

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aladdin

New Member
Joined
Aug 28, 2007
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11
Car
E300 Diesel
Serious Help needed!!!

got a 96 E300 Diesel (not turbo). It was started to give problems:

at idle it is OK. If I rev the engine I get plumes of white smoke from the exhaust. the engine seems to be mis-firing when it does this.

when driving the car jerks a lot, and gives off white smoke. it can be very rough. Drove onto motorway the other day too see if the problem was still present at higher speeds, and it was. at 60 it ket jerking all the time.

Took it to a merc specialist and he thought is was an EGR problem. But later changed his mind. (I cannot trust if he did anything to the EGR)
However he did point out that if he removed the vacuum from the EGR (assuming the EGR is the thing on the left of the engine as you are looking at the engine from the front) the problem went away. the reveing, white smoke and driving problem.
But I cannot run without the vacuum disconnected as the gears knock in and out while driving.
Mechanic said it was a big job, he might have to strip the manifold, it could be a air leak, or one of the vacuum pipes etc...
Anyone, please help, what it is wrong with it.

things i have done to the car:
replaced ignition barrel/switch.
new stainless steel exhaust, pipe runns from the cat all the way to the backbox with tail piece.
under car lighting (nice)

and recently (for my problem)
replaced : oil filter, oil, fuel fliter (main one and inline one) the air filter is clean so did not change that.:confused:
 
W124 or W210? If W210, turbo or non-turbo?

Which vacuum pipe did he take off?

You need a better mechanic

Nick Froome
www.w124.co.uk
 
Sounds like either the gearbox vacuum modulator is leaking ATF into the manifold.
 
Bolide, its a W210 non turbo.

appareantly theres a vacuum pipe, that I think feeds the EGR. (a cylindrical device that sits on the mixer???)

Dieselman, where can I find the vacuum modulator, what is the ATF and which manifold.
I must apologise for my lack of descriptions and my getting around the car engine, any help from you guys would be very much appreciated.
 
Part number 5 is the EGR valve. It leaks gas from the exhaust back into the intake manifold.

try disconnecting and plugging the vacuum line to that valve only.

http://www.detali.ru/cat/oem_mb2.as...GM=717.446&CT=M&cat=19T&SID=14&SGR=090&SGN=06

The gearbox changes go harsh as a result of the vacuum being removed from all applications including the shift modulator on the box. Sounds like your mechanic has remobved the wrong line or left it unplugged.

ATF is gearbox fluid. If the modulator onthe gearbox splits ATF can be sucked into the engine. Check the ATF level.
 
dieselman.
the mechanic, took the vacuum pipe off part number 5 (from the top end, ie as you are looking onto the engine) as you pointed out. thing is when this is vacuum pipe is pulled out, and I rev the engine everything is fine. no smoke, and doesn't feel like it is mis-firing.

what should i disconnect and plug in where.
 
I've checked the ATf level and it looks to me it is at the right level, although I will check in the manual I got with it to see where it should be.
(there are two levels, one for 30 and one for 80, can I assume this is engine temp it is talking about. does it need to be in parked or neutral for me to check? )
The ATF fluid also looks very clean.
(BTW: the car has only done 72K) there is a service history, althoough the last service was done by a local shop, rather than a merc place. (ie at 71K)
 
Check the ATF after a run witht the gears in Park and engine running.

Plug the pipe with a ball-bearing or bolt to stop vacuum leaking.
 
thanks, will check the ATF after running and will also plug the vacuum pipe with a bolt.

many thanks for your help. I cannot do this at the moment, as I am at work, but will have a go later today.

at what time are you logging off this forum, as I wold like to reply to you as to the outcome of your suggestion? Tomorrow is Saturday, and I would like to get the car sorted.
 
right,
I've checked the ATF level. Car is running and is at just over 80deg. the level on the dip stick is at the top end of the 80 mark.

I've disconnected the vacuum pipe and shoved a bolt down it...
WOW! ever since I've had the car I have never had the car running so smoothly, and the gear changes are....well...not noticable....unbelievable difference.

so where are we with this. Is there somethng wrong with the EGR - does it need replacing.
OR
is there something wrong with the vacuum somewhere?
 
Replied to PM.

Good news, just leave the pipe disconnected and plugged, you don't need the EGR at all, it's detrimental to engine smooth running.

It's there as a crude NOX emission control, but causes soot in the engine.

Just as an aside Hino Trucks commissioned a survey to find the effects of EGR and found it noticibly reduced engine life due to soot particles. :(
 
>> It's there as a crude NOX emission control, but causes soot in the engine.

Quite - I'm not usually a fan of making ill thought out modifications, but disabling EGR is something I happily do on all my cars. Our Astra ran like a different (better!) car when I disabled EGR.
 
>> It's there as a crude NOX emission control, but causes soot in the engine.

Quite - I'm not usually a fan of making ill thought out modifications, but disabling EGR is something I happily do on all my cars. Our Astra ran like a different (better!) car when I disabled EGR.


I will try it on the SL500 over the next few days
 
Malcolm,

One thing to be wary about if disabling EGR on modern cars is whether the engine management unit will pick up on it, go into limp home mode, and throw a code.

The engine management can pick up the tweak via a couple of methods; some EGR valves have a potentiometer in them that tells the ECU where the valve is, and some systems will want to pick up an increased flow through the MAF.

I don't know if either of these concerns will affect your car, so, it may be best if you make youself aware of the likely consequences before making a change.
 
Malcolm,

One thing to be wary about if disabling EGR on modern cars is whether the engine management unit will pick up on it, go into limp home mode, and throw a code.

The engine management can pick up the tweak via a couple of methods; some EGR valves have a potentiometer in them that tells the ECU where the valve is, and some systems will want to pick up an increased flow through the MAF.

I don't know if either of these concerns will affect your car, so, it may be best if you make youself aware of the likely consequences before making a change.

If I just removed the vacuum I do not think that the management would know, I will post back
 

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