OM612 Clear fuel lines replacement

hkpierce

'02 140 Hi BlueBlk Pass
I was smelling diesel but could not find the leak over an extended period of time. Nothing dirty around the filter. Nothing and bone dry around the injectors and glow plugs. While I have had problems with the pressure control valve, it was all dry to touch (since you really can't see it). But the front of the engine was getting more and more dirty and constantly wet. But (I discovered since) not all of that was related to diesel - as there was a leak of coolant on the water pump return that only leaked when the engine was hot and the system under pressure. Further, I wrapped some of the clear fuel lines with paper to see if I could isolate the leaking line. But you can only go so far with this technique - and the all the paper stayed dry. Both pumps appeared dry. So I proceeded to change out the 3 clear fuel lines. This is only applicable to OM612 engines.

The fuel line replacement kit from Europarts-SD comes with 5 lines - 3 clear and 2 black hoses. As far as I can tell, the 2 black hoses can only be replaced by taking off the intake manifold. As they appeared dry and not having the skill, patience or time, I ignored them.

In the poorly drawn diagram below as shown 3 lines -
RED - the supply line from the fuel filter to the low pressure pump
BLACK - the 3-armed line. The supply line from the low pressure pump to the high pressure pump and to an unknown purpose line under the intake manifold (maybe a supply to a post-rail cavity of some type?)
BLUE - the supply line to the back of the rail

Fuel line diagram (800x576).jpg

RED line: By far the easiest line to replace. To get working room, disconnect the top intercooler hose, top 2 radiator hoses and the vacuum line crossing in front of the low pressure pump. There are several clips that hold the line in place. However, the one(s) inside the intake manifold cavity are basically unreachable. The ones near the front of the engine are heat, age and chemical compromised and break immediately. Both ends are Voss connectors. That means push the white arms in until they lock in place, then pull off. If the first time, they will be hard to pull off. Fish the new line back through the intake manifold cavity, silicone grease the Voss connectors, and re-attach.

Because of the broken connectors and the ones that you cannot get to, use zip ties where you can, and use loom protectors for the areas that you cannot so that friction and vibration don't cause a hole in the new fuel line. The picture below shows one of the zips I used and the red loom in the back protecting the line as it comes out from under the manifold.

Fuel line tie down.JPG
 
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hkpierce

'02 140 Hi BlueBlk Pass
To access and replace the Blue and Black lines, some people have posted reports that they were able to do it only by removing the top cross-member, pushing the radiator package back, and removing the fan. God bless them, but I couldn't see how I could do it that way. I chose to swing out the radiator. That gives clear access to all the parts that need to be replaced without doing it blind and guessing.

P8252038 (800x600).jpg
The Blue and Black lines weave back and forth around each other, so removal and replacement is a dance between the two.

First, remove the torx bolt that clamps the two lines into the high pressure pump. Disconnect the two clips under the high pressure pump. These clips are hinged at the bottom and use a notch/hole type connection at the top.
P8262042 (800x600).jpg
P8262043 (800x600).jpg

There is a difficult metal clip holding the Blue line behind the right idler. In my case, the loom-type fuel line protection was disintegrating as I worked with the lines.
Fule line clip hidden.JPG

Blue line: On the top of the engine and inside the intake manifold cavity, disconnect the clips (red circles) and remove the front intake manifold bracket (blue circle) to give more working room.

Fuel line end rail clips top.JPG
 
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hkpierce

'02 140 Hi BlueBlk Pass
Blue line (con't) Now the hard part - the Voss connector at the top of the engine is near the back of the manifold but just before the pressure control valve.
Fuel line end rail general (800x600).jpg

The Voss connector's legs are position to permit you to push it from the front and lock them in the open position. Once open, it is very troublesome to get it out if it is the first time. Wiggle, wiggle wiggle.
Fuel line end of rail.JPG

Once the connector is off, pull the line back. Note how you get the connector past the back bracket. The new line will have to go the same way. Now that the top of the line is free, I fed the lower part of the line up and out.

Black Line: Now that the Blue line is out, Black line. It is the 3-armed line. Remove the Voss connector at the low pressure pump. Next, remove the Voss connector behind the intake manifold. It is really buried - but visible. Again, troublesome to get off if not taken off before. Pull the arm from under the manifold. Then slide the unit to the right past the idler pulley and oil filter.

Fuel line under manifold marked.JPG

New Lines: Position the new 3-armed Black line in first by sliding it in the reverse on how it got out. Feed the arm under the manifold and the other arm under the high pressure pump to access the back side of the pump. Don't connect anything yet.

For the Blue line, I first fed the pump side of the line from the top down. Once generally down enough, then silicone grease up the Voss connector on the top side, lock open the Voss connector and feed the rest of the line to the back of the manifold. It is a bit of a fight to get the connector alignment. Then work the loom positions such that the clips work.

Now, work on both the Blue and Black lines into position to enter into the high pressure pump. The Black 3-armed line goes low under the pump, then crosses under the Blue line. The problem will be that the lines will be stiff, and they do not like the cross. And I don't trust the clips to hold. I used a hair dryer to warm up the pipes to make them easier to push into place and bend around each other. Once about right, silicone grease the connectors and clamp the high pressure pump ends in - make sure that the alignment of the flat clamp properly fits with the Voss connectors' ridge pattern.
P8262054 (800x600).jpg

Now the upper arm of the Black line needs to be fiddled with. Check with the T-fitting. The harness protection should be just above the gap between the block and the pump. Otherwise the line sits too low and conflicts with a torx bolt head. Around this time is to force the Blue line back into its metal clip located behind the idler pulley.
Fuel line conflict star.JPG

Hitch up the Black line's Voss connector under the manifold (silicone grease the fitting).

Silicone grease the last Voss connector on the upper arm of the Black line - position it ready to go. Now hitch up your vacuum priming system [if you don't have one - you now have the parts to make one] and reprime the supply lines and low pressure pump. Swap out the primer with the new prepped Voss connector.

Look around to see if there are any other plastic-metal conflict that may need adjustment or protection. That should do it.
 
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hkpierce

'02 140 Hi BlueBlk Pass
I mentioned above that the Europarts SD OM612 fuel line replacement kit comes with 5 lines, 3 are the clear plastic discussed above, and 2 black lines. I mentioned that I thought the only way to replace the 2 black lines was by removing the intake manifold. It turns out that the black fuel line returning fuel from the rail to the fuel filter does not require the intake manifold to be replaced. If you happen to have the 5 steel injector lines off, the plastic fuel line to the pressure relief valve off (the BLUE line above), and the engine harness on the top end of the engine off, you can access the clamp holding the fuel line on. Further, while I had the molded version of the fuel line at hand because of the kit I bought, I see no reason that a standard generic 5/16 fuel line can't serve the same purpose.

H fuel line.jpg

However, the second molded fuel line on the other side of the fuel temperature sensor still seems to need the intake manifold removed to access. Don't touch it unless you are prepared..... Here is a picture from MillionMileSprinter showing this last fuel line on a 612 with the 612's manifold replaced with a 647 manifold - thus exposing the line:

Capture2.JPG
 
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hkpierce

'02 140 Hi BlueBlk Pass
Re: OM612 2003 hard cold start & fuel leak

I have also heard of people cutting the clear plastic off the lies and fitting rubber fuel pipe onto the stupid plastic connectors with the unintuitive white clips. It would be alot cheaper than $160 but if the problem is the connector then it wont solve it.
I have read of some that were thinking of doing this, but none who have actually done it. I question if it is possible on an OM612 for at least three reasons.

1: The Voss connector is designed to grip a flange. I know of no other connector that will do this job on the OM612 fittings. That means the Voss connectors from the old plastic lines will have to be reused. Further, remember that the Voss connectors on the high pressure pump are not the same as those elsewhere on the plastic fuel line system.


2: There is going to be a clearance problem for the black replacement fuel lines and the clamps for at least the two lines connecting with the low pressure pump and the two lines connecting the high pressure pump. That means it may not even be possible to get the new lines to attach where necessary. Here is a picture of what the Voss connector looks with a normal fuel line and clamp:
PrimeModify.jpg

3: Using the thicker black fuel lines will mean that it will not be possible to follow the same routing as the original plastic lines in at least two places - under the high pressure fuel pump and the T-fitting behind the idler. This means the new fuel lines will have to be rerouted in some manner on both sides of the engine. That reroute will likely create new problems.
Fuel line conflict star.JPG
P8262042 (800x600).jpg
 
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mover_boy

Member
So after you changed the lines, how do you prime the system? Does start right up or there's air in the system problem ?
 

hkpierce

'02 140 Hi BlueBlk Pass
So after you changed the lines, how do you prime the system? Does start right up or there's air in the system problem ?
No - it will not start right up. Priming is another problem for OM612s and has its own discussion - and I provided one of the links above - now also below.
Now hitch up your vacuum priming system [if you don't have one - you now have the parts to make one] and reprime the supply lines and low pressure pump.
 
how many hours did this take?

debating if i should do it myself or pay someone.

I've replaced two clear lines because i had air bubbles in them. the van has sat nose down in the driveway for 5 months while doing my build out and I periodically check the lines for air. today there was a fair amount of air. so i have a leak somewhere. ugh. I have no tried starting it
 

hkpierce

'02 140 Hi BlueBlk Pass
Depends on experience, previous mods and luck. Some have been able to install the lines below the HP pump without swinging out the radiator. That still requires the upper part of the fan shroud to be removed (if it has been modified). Since I am slow and used the radiator swing out method, it took me about 4 hours.

But are you really sure that the plastic lines are cracked? Air leaks are usually elsewhere on the system and old/reused O-rings.
 
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i don't think the lines are cracked. i figured its more the o rings? should i start with just o ring replacement for every line? Probsbly less work eh?
 

hkpierce

'02 140 Hi BlueBlk Pass
i don't think the lines are cracked. i figured its more the o rings? should i start with just o ring replacement for every line? Probsbly less work eh?
Good start. But as the OEM design fuel filter has at least 8 possible locations for an air leak, not including a split return valve, if you see any air line line while running the source is likely there.
 
i replaced the fuel filter with a non-water one, and the valve on top of it, and the clear line that comes out of it, along with some black fuel lines, and used new *corrrect* hose clamps for all attachments concerning the fuel filter. months later bubbles start to show themselves. I would assume it would be somewhere between the Low pressure pump and the fuel filter, as thats the only place i can see bubbles. Could there be a leak in the LP pump itself?

is there a possibility it could be part of the fuel rail system? or one of the clear lines on the other side of the low pressure pump?


i seriously appreciate your help. thankyou
 

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