Priming Diesel after filter change in an OM366LA

#1
Hi again, as I ever so slowly learn how to take care of this truck I replaced the fuel filter yesterday. I had blindly hoped that the fuel system is self bleeding (some marine diesels are) but after about 30 seconds the engine stalled. So, does anyone know the process to bleed the fuel system of air?
 
#2
There is a hand pump on the side of the engine, below the fuel pump. You need to pump it a few times, then open up the bleed screw on the filter housing. Then pump it until diesel flows out the screw, then close the bleed screw and try start it again, you just have to keep on doing it until the motor starts.
 
#3
For my 917 just pump manual pump beside filter until resistance builds. Start.
Note the injectors do not require bleeding( in fact they are not accessible)
 
#4
Thanks guys, found the pump and got the engine running. After looking around a bit I am thinking they might have put in a way to prime not only the filter but also the injection pump. There is a fuel hose that goes from the filter housing to the injection pump. On the nut that holds the banjo fitting there looks to be a spring loaded ball in the middle of it. Didn't want to mess with it but it looks like maybe you could prime the whole system by pumping the manual pump while pressing in the ball. Does anyone know if this is correct?
 
#6
The only thing i would add to the advice above which is spot on is that if you replace the fuel filter you must make sure that the refit is correct. If the seal on the housing is damaged or simply not tight enough it could draw air in and this can cause havoc ie not starting or very lumpy.

The primer pumps can fail so its something to think about gor you never ending spares list

Neil
 

Ozrockrat

Expedition Leader
#7
Ok disclaimer first. I am not familiar with your model Mercedes. I am going off my OM926LA.

I think the fitting with the ball valve is where you connect an external priming pump.

Think of a stainless weed spray unit filled with diesel and a quick connect on the fitting you mentioned.

Also on my truck if you listen carefully and just pump until the air finishes bubbling back into the tank.
 

Sitec

Adventurer
#8
Hi Neil. Have you found that the filters you require are always available around the world or do you just carry enough? Working for a tractor dealership I have access to an array of parts and one of the things we carry on the shelf is a CAV filter housing (complete with hand primer) and spin on filter... I was thinking of fitting one of these near to the tank on mine and accessable, in the hopes of having an easy reach primary filter and accessable hand primer. Thoughts?

Did I see that you'd called in on Pairospam? That's a huge project he has going! I'll get there one day!

Following your build with interest Jonturgeon, the questions provoke thoughts and ideas in my build!! :)
 
#9
Mercedes fuel filters can be ordered in the US and Canada, arguably the worst place on the planet for Mercedes truck parts.
A pre-filter /water separator near the tank is a good idea. We use a Racor filter system (spin on plus water separator). Available worldwide.
Always carry a minimum of 2 extra filters, one bad tank of fuel can cause major issues.
 
#11
Adding a fuel/water separator is on the list. I already knew of Racors from the boating world, at least in the marine stores the filters seem a bit pricey (maybe they do not do that on the trucking side, will have to find out). Sitec, thanks for the tip on the CAV style filters. I'll do some digging around and see what I can find here in the US. I have already bought a 50 gallon alloy rectangular fuel tank that came off a wrecked Sterling local delivery truck. I hope to find an identical second one and end up with 100 gallons.

The boat is pretty much put away now, we are now waiting for the notification that our new 11.75" x 22.5" rims are available for pickup at the port in Baltimore. Once we find out we will head out, pick them up and move onto where the build will get going. Can't wait.
 
#12
I run a CAV filter with a water separator bowl as a pre-filter for both tanks, it protects the Pollock valve and is finer than the OEM fuel filters. They cost only $5 each, and takes me 10 minutes to change. I have a Face pump on each tank to prime the filter system, and that helps find any leaks and makes priming a breeze.
 

DiploStrat

Expedition Leader
#13
Mercedes fuel filters can be ordered in the US and Canada, arguably the worst place on the planet for Mercedes truck parts.
A pre-filter /water separator near the tank is a good idea. We use a Racor filter system (spin on plus water separator). Available worldwide.
Always carry a minimum of 2 extra filters, one bad tank of fuel can cause major issues.
Joe, thank you for posting this. I have been debating the virtues of a pre filter/water separator.
 
#14
We also run a Racor filter / water separator system between the tank and the OEM filters. As others have mentioned, it isn't all that expensive and a good investment in my opinion.
 
#15
I have two filters in place before before the engine original.

As the fuel leaves the tank it goes through an inline strainer. This is cheap and is a sacrificial filter. Its in place to protect the fine filter and water separator which is SEPAR.

The problem with putting a super fine filter in place before the original one is that one batch of deal fuel and the expensive filter gets clogged up and ruined.

Placing the cheap disposable inline stained in place up stream has saved my expensive filter many times now. I can even wash it out and re use it.

I carry some filters but so far in South America I have not had too much trouble getting parts. There are plenty of truck spares places that sell MANN filters so I don't anticipate a problem.

I would however always carry some fuel filters as one lot of rubbish fuel and you could be stuffed. There is plenty of water in the fuel here so a water separator is a must

Neil
 
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