jackbombay
2003 158" shc
Aug. 7, 2021 Some added edits per Jack Bombay request. Thanks goes to Jackbombay for the Write-up and the follow-up. 
I had the displeasure of removing the high pressure fuel rail from my OM612 recently, and I'm sure somebody has at some point successfully reinstalled a high pressure fuel rail in an OM612, but I didn't want to prove how stubborn I am, so I decided to put an OM647 intake manifold on my 612, which has much, much better access to the high pressure fuel rail.
So, both manifolds use the same gasket, but you do need to get a few parts from the junkyard or your dealer, you need the intake manifold support bracket, this goes from the intake mani to the engine block and mounts to the same hole that the OM612 intake mani mounts to, and you need a different coolant hose that goes from the 647 EGR valve to the coolant pump on the firewall, and you need 4 longer intake manifold bolts that go across the bottom of the intake manifold. The bracket is part number A6470960045, the coolant hose is part number 901 832 8023 C,the longer bolts that fasten the bottom of the mani to the head, well, nobody has a part number for them and they are not shown on any parts diagram, I got mine from a junk engine at a bus shop here in Idaho, the bolt has 100 mm of threads and is 8 x 1.25 I believe, the head of the bolt has some markings KXZ 8.8.
"the longer bolts that fasten the bottom of the mani to the head are part number 002-990-99-22"
Here are pics of all the parts,
The bolt,
There are 2 small 90* brackets that fasten the top edge of the 612 mani to the head, you will need to modify one of those to hold the fuel pressure sensor (I think that's what it is, signals that the fuel filter is clogged) OR you can lengthen the wires for that sensor before you instal the 647 mani, once the mani is in there isn't much room to get down in there to solder and heat shrink the wires...
This is the bracket before I cut and welded it, but if you just lengthen the wires when you have decent access you don't have to do this,
The fuel temp sensor (I think thats what it is) that is located at about the mid point of the rail will need just a tiny bit of plastic removed from it to fit with the 647 mani, when I was removing the plug from that sensor I did break off the retaining clip (due to the terrible access of the 612 mani) which resulted in it just barely fitting, you do have to remove the mounting plate, install the plug then reinstall the plate that the sensor is mounted to to get the plug on, but it fits fine if you do that.
Lastly, the banjo bolt at the back end of the rail need to be installed before you install the rail, or mani as with both the rail and mani in place you cannot get the banjo bolt in place.
Yea, EGR, I have a GDE tune, so my van runs fine without it, I do have the old EGR valve hanging from the firewall but I'm working on how to eliminate that...
The EGR systems are thankfully compatible so you can just plug your van into the OM647 EGR valve and the system will work properly.
I now have easy access to the injectors and glow plugs, the manifold cost me $100 off ebay, the bracket was $24, the hose was $5 and the bolts were free.
I did use a Sawzall to get the old manifold off, I do have a 3rd degree blackbelt with a Sawzall
I doubt (m)any people will do this swap, but for those for whom it might make sense they can rest assured that it will all bolt up pretty painlessly, with the exception of getting the 612 manifold out...
Here is the mani and fuel rail mocked up, to show it does fit, I can post a complete pic tomorrow.
While I'm editing...
There is a recent related thread with some additional information.
sprinter-source.com
vic
I had the displeasure of removing the high pressure fuel rail from my OM612 recently, and I'm sure somebody has at some point successfully reinstalled a high pressure fuel rail in an OM612, but I didn't want to prove how stubborn I am, so I decided to put an OM647 intake manifold on my 612, which has much, much better access to the high pressure fuel rail.
So, both manifolds use the same gasket, but you do need to get a few parts from the junkyard or your dealer, you need the intake manifold support bracket, this goes from the intake mani to the engine block and mounts to the same hole that the OM612 intake mani mounts to, and you need a different coolant hose that goes from the 647 EGR valve to the coolant pump on the firewall, and you need 4 longer intake manifold bolts that go across the bottom of the intake manifold. The bracket is part number A6470960045, the coolant hose is part number 901 832 8023 C,
"the longer bolts that fasten the bottom of the mani to the head are part number 002-990-99-22"
Here are pics of all the parts,
The bolt,
There are 2 small 90* brackets that fasten the top edge of the 612 mani to the head, you will need to modify one of those to hold the fuel pressure sensor (I think that's what it is, signals that the fuel filter is clogged) OR you can lengthen the wires for that sensor before you instal the 647 mani, once the mani is in there isn't much room to get down in there to solder and heat shrink the wires...
This is the bracket before I cut and welded it, but if you just lengthen the wires when you have decent access you don't have to do this,
The fuel temp sensor (I think thats what it is) that is located at about the mid point of the rail will need just a tiny bit of plastic removed from it to fit with the 647 mani, when I was removing the plug from that sensor I did break off the retaining clip (due to the terrible access of the 612 mani) which resulted in it just barely fitting, you do have to remove the mounting plate, install the plug then reinstall the plate that the sensor is mounted to to get the plug on, but it fits fine if you do that.
Lastly, the banjo bolt at the back end of the rail need to be installed before you install the rail, or mani as with both the rail and mani in place you cannot get the banjo bolt in place.
The EGR systems are thankfully compatible so you can just plug your van into the OM647 EGR valve and the system will work properly.
I now have easy access to the injectors and glow plugs, the manifold cost me $100 off ebay, the bracket was $24, the hose was $5 and the bolts were free.
I did use a Sawzall to get the old manifold off, I do have a 3rd degree blackbelt with a Sawzall
I doubt (m)any people will do this swap, but for those for whom it might make sense they can rest assured that it will all bolt up pretty painlessly, with the exception of getting the 612 manifold out...
Here is the mani and fuel rail mocked up, to show it does fit, I can post a complete pic tomorrow.
While I'm editing...
There is a recent related thread with some additional information.
Intake manifold swap.
Was wondering if anyone knows if the intake on a T1N ( "C" shaped intake that blocks half the top of the motor) can be swapped with the lower style intake that came on the 2004 - 2006 models. I believe some 2003 models even had the lower style. Just wanting to know if it will bolt up properly...
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