Oily inlet manifold and pipes.

jimmy

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WARNING DIRTY PICTURES!

After all the talk of MAS problems, I thought I would take a look at mine:

OilyMAS.jpg


As you can see, there is not much to it. Looks like a diode/resistor type thing. You can see in the picture that mine is very oily, so I thought I would see where the oil was coming from.

This is a picture of the inlet pipe at the top of the engine after the intercooler but before the turbo wastegate. It is lined with a very thick, gundgy oily mess!! This is when I decided to strip the whole of the inlet side of the engine and thoroughly clean everything.

ChargePipe.jpg


I removed the inlet manifold and all the associated inlet pipes from the turbo, intercooler and manifold. When I removed the bottom pipes that join onto the intercooler, about 1/2 litre of thick oil drained out. I used a spray gun to 'blow' brake cleaner through the intercooler until it was clean.

Inletmanifold.jpg


The inlet manifold is easy to remove and was also full of gundge.

Picture of the stripped engine:

Engine.jpg


I used lots of petrol and brake cleaner to thoroughly clean all the pipework until it was completely clean. I then reassembled everything in reverse order (Haynes terminolgy:D ) And amazingly it started first time and runs an ablsolute treat.

Obviously the oil in the intercooler was reducing it's efficiency and the gundge would have been restricting airflow and the dirty MAS might not have been working properly. The result is much smoother, faster throttle response. Since I fitted the tuning box I have noticed an increase in black smoke under very hard acceleration, today I have nearly cured it and there is hardly any smoke from the exhaust.

I am not sure where the oil has come from, the engine never uses any and I have never topped it up. The turbo was spotlessly clean so hopefully no problems there. The only thing I can think is that it is just a build up from the last 70K miles, the crankcase breather is plumbed into the inlet pipe just after the air filter box, so all the oily fumes are getting drawn into the inlet pipes.

Either that or the engine oil has been overfilled at sometime or I have a more serious problem that is not obvious to me. I shall keep an eye on it an re-check the pipes in a few thousand miles.

Amazing that it could be in such a state, especially with a full MB service history!!!
 

sym

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VERY brave man !

Sounds like it was well worth doing !! I scared myself today just fitting my bling bling mirrors - wouldn't dare take the engine apart !! EEK !

S.
 

Koolvin

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Originally posted by jimmy
WARNING DIRTY PICTURES!

After all the talk of MAS problems, I thought I would take a look at mine:

OilyMAS.jpg


As you can see, there is not much to it. Looks like a diode/resistor type thing. You can see in the picture that mine is very oily, so I thought I would see where the oil was coming from.

Jimmy I believe that is the charge air temp sensor!
 
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Steve_Perry

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Good one Jimmy :cool: :) Maybe a chat with the friendly local stealer service dept (do you have one that's friendly?) might throw up more ideas as to why the oil and gunge was there in the first place, given it has a full MBSH. :crazy: As you say, you'd expect it to be cleaner that it was if not spotless.

I thought the MAS looked like an exposed wire filament, be careful because it is extremely delicate, or so I'm told.

S.
 
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jimmy

jimmy

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Ahh, the Haynes manual also calls this the Air Temperature Sensor, is that different to a MAS sensor? If so then I dont have a MAS.:bannana:
 

Dieselman

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Jimmy

Koolvin is correct this is indeed the IAT (intake air temperature) sensor. The Maf is immediately after the air filter box if you have one at all. The ecu is able to use IAT, Manifold Pressure Sensor and accelerator position to set fuel quantity.

The oil is nothing to worry about, it is from the crankcase breather and vents into the air intake, also there will be a small amount from the turbo seals.

Are you sure you mean 1/2 litre of oil, this is a lot. Mine had about an egg cup full when I took it apart first time!

The black gunge in the inlet manifold is caused by EGR (exhaust gas recirculation), which is designed to reduce the excess air at idle so reducing the output of NOX (nitrogen oxide). It does this by returning some of the exhaust gas back into the intake via a vacuum valve.

The black carbon build up is normal, but in reality is bad news.

Not seen a 250TD in the flesh but nice to see it's exactly the same layout as mine only someone has nicked one of your cylinders.
 
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GazCaff

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Thread necromancy!!

I changed the rubber seals on my inlet manifold today to cure the blow-by oil stains on the cylinder head. The pictures above could have come from my car as that is exactly the state mine was in. While I had the inlet manifold off I worked a rag into each of the air intakes as the all had at least 1mm of cancerous oil/soot paste on them.

I'm glad I disabled my EGR a few months ago. I'm now considering looking into modding the crank case breather to blow into a collection can instead of into the inlet tract and making that kind of mess again.

Warning: One thing to watch out for is the plastic securing clips for the fuel injector pipes. On mine they had gone brittle and a couple of them were broken and the pieces of plastic were sitting on top of the inlet manifold. When I removed the manifold one of these pieces dropped into one of the inlet holes and was sitting on top of the valve (I was lucky that cylinder was on its compression or exhaust stroke). Fortunatley a long screwdriver with a blob of grease was able to retrieve the offending item. :)
 

bolide

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That's EGR crud. E300 Diesels are just the same - gluey crud everywhere

What's the engine code on that car? The E300 D is a 606 and that looks just the same but shorn of one pot

Nick Froome
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Dieselman

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They are the same family of engines. Isn't the 5 pot denoted 605?

As you correctly state the black crud is EGR filth and not directly a result of the breather, well at least the breather oil won't go hard without EGR soot.
 
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GazCaff

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The 5 pot is indeed a 605. I agree that the majority of the crud is caused by soot from the EGR but having it mingle with oil vapour from the crank case breather doesn't help. When I last serviced my car I could have filled a ciggarette packet with the amount of lumps of cogealed soot I pulled out of the rubber connections around the EGR housing.
 

tim.100

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bolide said:
That's EGR crud. E300 Diesels are just the same - gluey crud everywhere

What's the engine code on that car? The E300 D is a 606 and that looks just the same but shorn of one pot

Nick Froome
www.w124.co.uk

605.960 if you have the 150 bhp version (i.e. the turbo). The .960 is important when you order an exhaust etc. - ask me (or George Fraser) how I know...
 

Parrot of Doom

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I'd love to see a HOWTO post on how to disable that EGR system. My inlets are exactly the same, filthy.
 

Dieselman

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You cant do it on the 300Turbo due to the MAF sensor detecting the additional airflow at idle.
 

Dieselman

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The filter idea would work as the MAF would still see the reduction of intake air.
The 300D doesn't have a maf and uses microswitches to detect the operation of the EGR flaps and valve. Blocking the pipe should have worked as the valves would still have worked.

I really can't see combustion temperatures being a problem as EGR is used at idle and low load conditions only.

This makes me think..Has anyone got a scrap 300TD exhaust manifold to cut the pipe off?
 

Parrot of Doom

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The thread eventually arrives at the same conclusion - and that on the TD models, the buildup of soot is not an issue as its fairly light compared to the N/A models.

I doubt you'd find a scrap manifold, I'm led to believe these engines are extremely reliable, and the manifold is a pretty chunky piece of metal to rust through. :)
 

bolide

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Parrot of Doom said:
and the manifold is a pretty chunky piece of metal to rust through. :)
Particularly as it's aluminium...

Nick Froome
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H.C.II

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EGR is used to reduce peak combustion temperatures under high power O/P conditions, and not at Idle....

There is no tendancy for NOx to be produced at part throttle and idle conditions, Only at higher power and full WOT....

Its possible to block off the EGR pipe by making up a gasget but without a hole in the middle...Use sheet steel to make it with....
 

Dieselman

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H.C.II said:
EGR is used to reduce peak combustion temperatures under high power O/P conditions, and not at Idle....

There is no tendancy for NOx to be produced at part throttle and idle conditions, Only at higher power and full WOT....

Its possible to block off the EGR pipe by making up a gasget but without a hole in the middle...Use sheet steel to make it with....

Sorry, cant agree here.

EGR is caused when the volume of oxygen goes high compared to that of the fuel. This can only happen at low load conditions and especially at idle. The EGR valve is only actuated under these conditions.

Maybe you are thinking of petrol engines, don't forget there is no such thing a WOT on a diesel as the volume of air is constant per revolution as there is no throttle?
 
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