Had a driver come in last night saying that his wagon (Axor) was using about a tank of add blue every 500 km.Told him to VOR it and I would have a look.Thought it might have a split tank.
All seemed ok underneath so I tillted the cab.Jesus!!!
The turbo heat shield had split and you couldnt see the turbo,starter motor,cylinder block,turbo vane actuator or flap actuator for a mass of crystalised add blue.
Took over two hours to chip it off just round the blower and starter and filled half a dustbin with the bloody stuff.The two 6mm bolts that hold the add blue injector onto the turbo outlet had sheared.The add blue was just being blown out by the exhaust gas onto the turbo and instantly evaporating.And as the NOx sensor was sensing high NOx it just kept pumping add blue in to try to compensate.Will have to take the blower off tonight to clear the engine block and free off the actuators.
Was like chipping away at pink bloody concrete.Cant really understand how it built up to 3 or 4 inch thick though.You would think that the first layer would stop anymore coming out but I bet when its all off the bin will be full.And no fault registerd on the dash!
bit strange that it was up at the turbo considering ad blue is sprayed on to the CAT ,sounds like a bull story to me ,ad blue can’t travel up the exhaust system ,the ad blue nozzle /injector is designed to spray on to the cat which means it is travelling in the same direction as the exhaust gases…will add I have been repairing ad blue sytems since 2006 and have done the courses and refreshers
Another one last night.60 plate axor but this time the injector bolts hadnt sheared and were still tight but the injector face plate was loose and seemed to have burned away.
Not as much as the last one but still a quarter of a dustbin.
Thousand quid for a new throttle body and injector and a week off the road till the bits come!Weird crap this add blue.
norb:
bit strange that it was up at the turbo considering ad blue is sprayed on to the CAT ,sounds like a bull story to me ,ad blue can’t travel up the exhaust system ,the ad blue nozzle /injector is designed to spray on to the cat which means it is travelling in the same direction as the exhaust gases…will add I have been repairing ad blue sytems since 2006 and have done the courses and refreshers
Clearly your “course and refresher” have never looked at the Merc system.The add blue injector is about 2 inch from the turbo outlet and sprays into the throttle body where the exhaust brake flap valve is.
Never done a “course” I only work on the real thing you see.
Never been able to get a 2540 on to a desk yet.
norb:
bit strange that it was up at the turbo considering ad blue is sprayed on to the CAT ,sounds like a bull story to me ,ad blue can’t travel up the exhaust system ,the ad blue nozzle /injector is designed to spray on to the cat which means it is travelling in the same direction as the exhaust gases…will add I have been repairing ad blue sytems since 2006 and have done the courses and refreshers
Clearly your “course and refresher” have never looked at the Merc system.The add blue injector is about 2 inch from the turbo outlet and sprays into the throttle body where the exhaust brake flap valve is.
Never done a “course” I only work on the real thing you see.
Never been able to get a 2540 on to a desk yet.
I’m confused, throttle body in the turbo? Exhaust brake on a Merc? A 2540 with SCR? None of that makes sense to me
Throttle body is on the intake side AFAIK?
Mercs have a compression brake, similar to a Jake Brake, konstant drossel stoppenquik or constant throttle brake in English. AFAIK that’s all done internally. The first position on the stalk may be exhaust brake only, with the KD brake coming in with each click of the stalk/switch, but I can’t see the point of that, if it has an engine brake, it doesn’t need an exhaust brake, but I’m not German.
2540 was Euro3, it became 2541 for Euro4/5.
I’m no expert, so I may be way off, I’ve never had a spanner on a Merc, so excuse me if I’ve got it all wrong
On the box the part arrived in it is called a throttle body.Mercedes make it so I suppose they can call it what they like.Besides throttle bodies on petrol engines only use a flap valve to reduce air flow into the engine so the throttle body on a diesel just reduces air flow out of the engine by shutting off the exhaust pipe.If the gas cant get out it cant ■■■■ any in can it.Not rocket science!
Better tell Merc they dont make Euro 5 2540s up to 61 plate any more cos we got 6 of em sat in the yard or are my eyes playing tricks again.
Mercedes have never had a jake brake,Up until they used variable geometry turbos they had a compression brake which when you lifted your foot off the throttle the unit pumps where closed down so no fuel was supplied and compressed air was fed into the cylinders so it turned the engine into a compressor which absorbs power.
The reason they use the flap valve now is to equalise pressure across the turbo sliding vanes when the exhaust brake is applied to stop them being pushed hard up against the stop pins.On the old none gated turbos it just reduced turbine speed.
As I said, I’m no expert, that’s why I asked. To the layman the term throttle body implies that the part has something to do with fuel, your explanation clears that up. It makes sense, but I assumed that it would be called something different for that application, rather than having a one size fits all description.
A jake brake is a compression brake, and so is the KD brake, I never said they were the same design, just the same principle. An exhaust brake is a butterfly valve in the exhaust, the two are not the same, my question was does the Merc use both? Or now I know it’s the inline 6 you’re talking about, does it have something different again?
I forgot all about the Axor 2540, I was referring to the vee engines.
I know about the new engine, it’s the Detroit Diesel DD range. 11/13/15&16 litre capacity, the 15 and 16 litre versions have turbocompounding as an option.
You’ll know it well too very soon
The engine itself is good, but it’s the crap bolted on that causes the problems. EGR, DPF and SCR and not one system has had enough development time.
newmercman:
I know about the new engine, it’s the Detroit Diesel DD range. 11/13/15&16 litre capacity, the 15 and 16 litre versions have turbocompounding as an option.
You’ll know it well too very soon
The engine itself is good, but it’s the crap bolted on that causes the problems. EGR, DPF and SCR and not one system has had enough development time.
