Don_Karlos

Hi,
my name is Karl and I'm from Magdeburg, Germany. I am an automotive engineer and for 30 years in our business. But, that doesn't help at all now:-) I own a W906 Sprinter with an OM642 Diesel Engine. It is a 318 CDI. I bought it to convert it into a RV and work now for 3 years on it. In that time the vehicle didn't get enough running time and I had last year an issue with the diesel fuel. It is called Diesel Pest here in Germany. It is basically an over population of the fuel system with bacterias which are clogging the fuel system. I cleaned it all up and performed a system flush and renewed the low pressure fuel pump cause it was seized. After doing this engine started and ran fine.
Now after another 10 month I started it again and now I have the following issue:
I start the engine. After 30sec running the noise of the engine suddenly changes to a much harder sound for 2sec and the Check Engine Light comes on and stays on. After that event, the engine sound goes back to normal, but the limp home mode is active. If I stop engine and restart, CEL is still on, but engine can be reved up as normal up to the point when the strange combustion sound appears again. and so on....
I read out the error codes with star diagnosis and it shows 2016 001 Rail Pressure too low. If I check the Rail Pressure it shows in idle 260-270 bar which is totally ok. After 30sec the Fuel Pressure Control changes from Pressure Control to Volume Control. That is the point when the noise appears. I changed the Volume Control Valve. No change in behavior. I performed a Rail Pressure Deviation Check in DAS and had in the Moment of switching from Pressure to Volume Control more than 2 deviations larger than 25bar which has to be concidered as problematic. Strange is, that I see only to high Rail Pressure measurments... but Error says Rail Pressure too low.... Since the Valve is new, I am at the end of my skills.
I need never get old and a little help;-)
Karl

Rail Pressure Deviation
Sorry for Quality....

kajtek1

Dump air is 1 of the reasons I moved from Poland to dry-air California and Nevada Snow had something to do with it as well...
Your picture is unreadable, but my experience with algae in diesel fuel is that it clogs the filters, so beside draining the tank and refilling with good fuel - you need to carry spare filters and be ready to change them on the road (I know it is a bear on OM642 engine)
So what is your low fuel pressure?

John CC

Yes. Also, check the strainer in the tank, flush the tank as good as possible, carry extra filters, and run a biocide like FPPF Killem Biocide or Power Service Bio Kleen in the fuel for a couple of tanks.

Quint22

Not sure what/how it was flushed but ya mention it sat for 10months then had similar problem. Could be that once it had the algae and then sitting again even though flushed allowed it to come back quicker then last time.
All filters like mentioned and use of biocide is what I would try. May end up needing a fresh flush then use of the biocide and regular maintenance if possible to keep it running strong.

Thankfully knock on wood I have not ran into this problem so far. Hoping I dont have to deal with it. It is a bummer that diesel now a days cant handle sitting for extended periods of time. Atleast the stuff we get in the US. Not like before where it could sit for years, many years if it was biocided and filtered properly while in storage.

kajtek1

I beg you to differ.
Last year I restated the car sitting in the garage for almost 3 years and OM651 engine restated on 1st turn.
Back in California, I bought Diesel Pusher, who was park under the tree for at least 7 years and I used all 120 gallons in the tank to the last drop. But I found a case of diesel treatment, so likely it was added (the owner died when widow could not tell.
The only algae I had was when I had to move my bus conversion to city along the delta. Bus was sitting for over 3 years and when I finally found a buyer, I delivered it 500 miles and had to replace fuel filter due to algae. Still drove it to the destination on old fuel mix.
So it was accumulation of moist air and open tank vent. to create some troubles.
Modern vehicles do have pressurized fuel tank, so I would want to hear from Don if he had the fuel system open to introduce the moisture?

Quint22

That makes sense I guess. Hoping I dont have the issue with my old excavator when I finally get to try using it again, been sitting a couple years.

From what I understand and could be wrong the older higher sulfer diesel was more stable or it could all just be propaganda as I was reading up a bunch on it when considering a diesel storage tank for longer periods. Im sure the sealed pressurized tank makes a big difference. Didnt think about that.

John CC

It's not the fuel, and it's not a "new" (since the introduction of ULSD) problem. The algae grows in the interface between the fuel and any water that gets into the tank. Whether it enters through the tank vent as vapor and condenses, or is entrained in the fuel when refueling, is irrelevant. The water separates from the fuel over time and settles in the bottom of the tank (where the pickup is) and the algae grows and coats the strainer and tank.

Water and Diesel fuel have closer specific gravities than water and gasoline, so it is more likely that Diesel fuel will "mix" with water when agitated. (Ethanol in gasoline is a whole other animal.) There is a reason why Diesel fuel systems have water separators and gas systems don't... Long periods of sitting with any water in the tank, or in a humid climate with a vented tank, pretty much ensures there will be problems.

Quint22

Good info guys appreciate it. Have more reading to do on my end.

Don_Karlos

Hi,
many thanks for your comments and the infos given. The system was flushed with a special diesel anti bacteria additive. The filter is new. Since the problem occurs every time exactly 30 sec after engine start (engine starts as it should) and the idle is strong and stable before and after the noise occurs, I don't think, that it is a result of bacteria slime. It happens, when the ECU switches from pressure regulation valve to volume regulation valve. When this happens, the rail pressure goes up from 260bar to 450-600bar for the time the noise is there. after 3 sec the rail pressure drops back to 260bar and the noise disappears.
Any further ideas?
Karl

pyb

Karl, Did you ever find a solution to this ? I am having a similar problem.

John CC

It sounds like either the pressure is jumping up too high, or the pressure jump is normal and the pressure relief valve is noisy.

Don_Karlos

Hi,
I`m sorry, but I didn`t fix the issue. i still have the Van and i am still struggling with it...:-) What happened so far:
I didn't find any single root cause for the behavior. I cleaned the Fuel tank and Lines again and changed the Filter. No change in the symptoms. I finally changed the Volume Control Valve on the High Presure Fuel Pump and... it ran suddenly allmost fine. At least it "survived" the point of Check Engine light after 30sec. It ran than for a few minutes and than it starved. After this it was impossible to start it again. This is the current state. I think, that this is all caused by the old Diesel and its contamination by bacterias. The old Volume Control valve was somehow blocked in its normall funvtion- and the circuit after it. After changing to a new working valve it blew all the bad stuff behind the new valve into the Rail and the Injectors, causing them to clog. I will start from scratch and clean or even exchange eveything from Tank to Injector Tips..... Mud in the Fuel system is bad ;-)
What do you think? Does that make sense?

pyb

Hi Karl, thanks for getting back and sorry to hear you haven't been successful yet. I'm also struggling with the consequences of "Diesel Pest" in my OM646 vito. My idle is normal for 30 seconds, after that the pressure oscillates between 150 bar to 400 bar. I am about to replace the Quantity control valve, hoping this would solve the problem.

John CC

Unless you somehow bypass the fuel filter, the contamination shouldn't make it into the rail and injectors. Hopefully, yours is not the exception. Likewise, it should keep water out.

If you have algae in the tank, you need to to flush it out or you'll keep having clogged screens and filters for the foreseeable future.

pyb

John : I've already replaced the lift pump, fuel filter and wiped the fuel tank. However, the problem Karl and I have is that there might be existing contamination past the fuel filter.

John CC

Anything that can get past the filter should respond to a fuel system cleaner, unless the filter somehow failed to do its job.