CDI Slug

[M80]

Thanks for the informative reading so far and for that hoped in the future.

To the problem(s). My C220 CDI(2001) 80K miles recently developed the safe mode symptom when warm, was ok when cold. I have noticed a little black oil from the inside of the front skirt o/s. With developing education I believe this is possibly from the turbo, at the intercooler connection? The engine oil is very fresh, the leaking oil black possibly because of the turbo temperature??
The car has enough power to pull away smoothly, in fact drives smoothly. Acceleration is abismal, economy is reduced. After reading threads I replaced the Air Mass Sensor, problem not rectified. It least I have the recomended spare now.
I got the missus to rev the engine (she with eyes closed and wanting to wear a crash hat) while I checked around the whirly bits. At 4K revs the waste gate shows no response (I assume it should be at least starting to open, its free to move when engine stopped). At these revs what feels like good pressure can be felt from the air duct diconnected at the intake manifold

On forum recomendation the slug is booked in at the specialist but this is 2 weeks away. Any pointers would be appreciated. Thanks in hope and anticipation.

 

[mercedes13156]

Try this one. I've got a C220 diesel. Only got it recently. I knew it would be slower than the C180 it replaced, but I was disappointed at how slow it actually was. Consumption was poor as well. I was looking at the motor last week and decided to give it a rev, as it sounded rough. I noticed that there was a load of slack in the throttle cable. I got the family spanner out and took up the slack and it's a different car. It's not a V8, but it goes much faster, revs higher and gives a bit better consumption. I also put a cleaner through the fuel to clean the injectors and that improved things a bit as well.

It was two minutes work. The throttle cable comes up at the top right corner of the bonnet.

 

[jberks]

... I replaced the Air Mass Sensor, problem not rectified. It least I have the recomended spare now.

On forum recomendation the slug is booked in at the specialist but this is 2 weeks away. Any pointers would be appreciated. Thanks in hope and anticipation.

You've already done the right thing by booking it in. Sure you can fix it yourself, but only when you know the true cause, which requires a reader. Otherwise you end up, as you have, wasting money replacing perfectly functional components or disturbing things to the extent that they stop working. As I'm sure you know, when it goes into safe mode, the error is stored. Without this error code, you, and we are guessing. I could suggest several things but be completely wrong. Wait for the fault codes, get a quote from the specialist and then, if you're not happy, bring that info back.

 

[M80]

Thanks for the replies. I like the idea of a code reader so I priced the gear (for a laptop) at Euro parts, over £1K for the software and leads relatively inexpensive. Overall tooooo much for a guy with one merc.
I've read members talking of handhelds, are these worthwhile and what sort of cost? And then which and where?
Thanks for the thoughts of cable and injectors. Don't expect cable slack to be the problem the fault was too sudden, and intermittent. I think i'll wait for Mr specialist to comment before pouring cleaners in the fuel. But ideas appreciated thanks.
With thought my best guess so far is the fault to be within the inlet manifold, I hope to be able to be lookin' over the Big Steves shoulder (SPR Autos) while he investigates. I'de like to uncover some of the mysteries from under this bonnet.
I'll update after Monday.

 

[M80]

For those interested in my update.

Mr Specialist fault finder found the glo plugs all to be faulty, the car starts easy and he and I could not see the connection to the problem.

No fault codes could be read until the car had been run into safe mode and pc connected with engine still running. Ther were many fault indications that related to the air system. He suggested that the post intercooler temp sensor or pressure switch maybe the cause.

Replaced temp sensor, no joy, replaced pressure switch, no joy, replaced MAF again in case 1st replacement was faulty ( as you gather now clutching at straws), no joy.

Symptoms- when cold car is fine not powerful, but is cold and diesel.
above 50deg engine spits back 2 or 3 times thru rev range (up to about 2.5k).
When hotter possibly 70deg there is excess black emissions at rear (I think unburnt fuel) prior to car going to safe mode, then seems to run clean. Ecomomy is down.

Now in my trial and error and error and error fashion I wonder if the lamba sensor is attempting to compensate for a lean mixture and still seeing lean mix with excess fuel so trips to safe mode??????

Maybe the next stop should be the stealership, but having read the reads from here I hate the idea of giving good money to bad attitude.

My Mb is a lovely car very comfortable and looks great, but now feels like something of a fliipin pain. On Sunday I return to the BM dealers for a test drive. We also have a 95, 320i Tour 160K miles pulls like a tatty horse (its well used and a bit beaten) and BM have given good service.

As always any suggestions gratefully recieved.

 

[jberks]

forget the stealership, you can run up £1k easy and still have a duff motor.
I know with my hard to diagnose fault, (3 attempts by the dealer with no joy) I gave the indie the car and left it with them. Took a few days but they got there in the end.

I'd rather pay someone to muck about at £40 per hour than £95, plus indies generally don't book exact hours but just charge a sensible price for the job, whereas the dealer will charge for every millisecond, whether they fix it or not.
Is your specialist a proper Merc only specialist or a general mechanic. With faults like these you need someone with the widest MB experience to give the best chance that they've seen it before, plus someone with a working 220 sitting on the forecourt that they can swap parts off to try.

 

[Dunhamkid]

I had similar symptoms on a VW diesel when the EGR valve was faulty, ie no power, black smoke and "spitting"

 

[M80]

Thanks for the suggestion Mr DunhamKid, I can see how the EGR may be the problem, If this is the unit that bolts to the front of the intake manifold i've already removed this for inspection. Definitely coated with black soot I couldn't create movement of the, what I assume, to be a valve operated from the diaphram by a pin across the centre. Anyone know if this should move easily by creating a vacuum or otherwise?

 

[Dunhamkid]

ERG valve on my Mercedes is situated at bottom of inlet manifold and is vacuum operated. There also appears to be a lever operating a rack which open/closes ports in inlet manifold.

On my VW I disconnected vacuum line and blocked it with a matchstick. Started engine and ran car, 100% better but was still hesitant from tickover so I replaced EGR valve (10 minute job, £55) and car has run ok since

 

[M80]

For those with interest,

Today the mo mo went into the SPR specialist. Steve has discovered a fracture on the intercooler, found in an out of reach place.

Of course this explains the management system not managing the mixture correctly and not being able to compensate then going to safe mode.

The small amount of oil leaked is apparently from that which would have developed over a period then lying within the intercooler from the turbo. Apparently it is not unusual to expect a little oil passing the turbo.

I am at a loss to understand how the fracture has occured, not recalling any sort of event that could cause this, but hey at least the problem should be sorted in a couple of days. Then I can hope that motoring will be back to normal.

The missus has fallen for the baby BM we drove last week so is very possible that the 220 goes. Any ideas where is good for a response?

 

[piestore]

220 cdi

Hi

nice one Steve, Its not uncomon for the intercooler to fail for no good reason, but it is somtimes due to excessive back pressure in the exhaust causing boost presure to rise above normal

 

[television]

Thanks for the suggestion Mr DunhamKid, I can see how the EGR may be the problem, If this is the unit that bolts to the front of the intake manifold i've already removed this for inspection. Definitely coated with black soot I couldn't create movement of the, what I assume, to be a valve operated from the diaphram by a pin across the centre. Anyone know if this should move easily by creating a vacuum or otherwise?

Just for reference, the EGR valve only opens when the car is running at steady speed,ie motorway, its purpose is to return any emissions from the exhaust back into the inlet manifold. It has a spring inside the valve that keeps it closed during idle, after X miles the thing gets coked up and sticks partly open, this will make the idle very rough, it is better to replace it rather than clean. this thing sits in the exhaust manifold and the high tempertures do over time destroy the spring, so don't waste time in trying to clean it.

Malcolm

 

[tamrsoft]

I have a similar EGR unit - how does it work?

EGRs seem to vary in design, I have a unit that sounds identical to that of C220chugger's and have not been able to see how it works. There is a solid shaft or tube across the orifice that leads from the vacumn unit into the chamber that the s/steel pipe from the exhaust cooler leads into. I think I can see the round head of a simple valve but cannot see any passage into the main unit by which the re-cycled exhaust would pass into the inlet manifold. Is it possible to test such a unit out, ie by sucking on the tube to the vacumn unit..

 

[television]

EGRs seem to vary in design, I have a unit that sounds identical to that of C220chugger's and have not been able to see how it works. There is a solid shaft or tube across the orifice that leads from the vacumn unit into the chamber that the s/steel pipe from the exhaust cooler leads into. I think I can see the round head of a simple valve but cannot see any passage into the main unit by which the re-cycled exhaust would pass into the inlet manifold. Is it possible to test such a unit out, ie by sucking on the tube to the vacumn unit..

The EGR valve can sit in one of two places, on a pipe between inlet and exhaust manifold, or on the cylinder head controling the flow between internal passages, they can be vacuam or ECU controlled, the valve is only opened during peak NOx output conditions, on our car they are on the head and not easy to test. external valves are easy to test just by clamping the pipe.

Malcolm

 

[tamrsoft]

How do you test

Mine is an aluminium casting that sits on the end of the inlet manifold and connects to the Charge Air pipe on the input side. I'me not sure how easy it would be to test. At idle, it should non-operational with the valve closed (no EGR return). From idle, I would have to find a way of opening it presumably by applying a strong suction to the vacumn pipe to see if it screwed up the idling. If working correctly, just removing the vacumn pipe would appear to make no difference to the idle performance. Since the inside of the valve and the inlet manifold is heavily sooted up, I assume it must working somewhere along the line.

 

[television]

Mine is an aluminium casting that sits on the end of the inlet manifold and connects to the Charge Air pipe on the input side. I'me not sure how easy it would be to test. At idle, it should non-operational with the valve closed (no EGR return). From idle, I would have to find a way of opening it presumably by applying a strong suction to the vacumn pipe to see if it screwed up the idling. If working correctly, just removing the vacumn pipe would appear to make no difference to the idle performance. Since the inside of the valve and the inlet manifold is heavily sooted up, I assume it must working somewhere along the line.

Garages use hand held pumps to test when the unit is off the car.

malcolm

 

[M80]

Mr Piestore you had me a little confused with the exhaust back pressure theory. This caused me to consider how excessive pressure could be created in the inlet flow line.

A couple of days prior to the first safe mode trip I had some irritating prat preventing me from driving at a reasonable rate on the M60, finally pulling to the left only to give his Fordster the right boot. Me of little patience for mt 'eads did same, missed a gear (Is a many geared manual by the way, needs an LED readout like the old Suzi 550) revved the Merc to limits, oops. Left the bugger lookin at tail pipes but was most definitely not cool about it. Bit of a prat myself actually.

Any way I now wonder if the waste gate could be iffy and allowed for over revving of the turbo and possibly excess pressure into the intercooler.

Thoughts anyone?

 

[piestore]

cdi lop

HI

No thats not a possible cause as you don't have a waste gate, the boost pressure is controled by the the ECU via the variable geometery turbo.

It is not unknown for the Kat to break up and block the centre exhaust box when this happens you create excesive back pressure which in turn increases the pressure in the boost tract which can result in broken intercooler, they also break for no reason other than poor manufacture or external damage

 

[M80]

Now I have the car back. Not had much chance to use it apart form a good test run but seems back to normal.

Thanks Steve and thanks to all for the thoughts and suggestions.