Bleeding fuel filter

Guys I am so damn sorry for another air in fuel line thread. But this has been plaguing me for a month. It's an '03. I couldnt get the Water in Fuel light to go off, so decided to install new filter. I have been having air problems so I paid attention to the fittings on the filter when I swapped it. I put a new oring on the WIF sensor; it seems nice and snug. The oring on the new filter where the Clogged Filter sensor( isnt that what it is?) mounts is nice and tight. I purchased a new fuel line from the filter to the LP pump as the previous owner had broken the connector(shocker, I know). Basically, all of my connections seem good. I hooked my MityVac up to the line returning to the Clogged Filter sensor and am getting a nice vacuum, but there is still air in the damn line. Where is it getting into the filter? The water drain appears airtight, but then again my eyes are not a pressure gauge, lol.
Any tips for sorting this out would be appreciated. I have read most of the threads regarding air in lines, but I am still at my wits end. I have some choice words for Mercedes engineers.
Oh, and to top it off the WIF sensor plug wont connect properly so that is why my stupid WIF light was on, and will remain on apparently.
Thanks!
J

Had the same problem forever, my fix came when I replaced the filter without a drain hole and without a WIF sensor hole, as seen here https://sprinter-source.com/forums/showthread.php?t=20104&highlight=p9436

I fought this is my 02 for a month and I am only 3 weeks into driving without air in the lines... I know it is frustrating. This is what I finally did: I took out the filter and bracket because I realized that when I screwed the water bleed valve in all the way it let air in. If I would screw the water bleed valve in until there was about the thickness of a penny between the valve and the filter no air would pass. (I have a Hengst filter by the way). I went to Harbor Freight and bought a package of o-rings. I placed one over the inlet screw on the water bleed valve and tightened it down on the filter. The o-ring insured the proper gap and added to the seal. I did this with the filter in the holder out of the van. I then installed the filter/holder at the same time. Then I took an o-ring and pushed it to the base of the area on the filter where the return ling (fuel heater?) connects because I thought maybe air was getting in there. Then I went to Advanced Auto Parts and bought some fuel injector clamps (a worm drive type clamp was on the inlet previously). I replaced the hose clamp on the on the inlet hose. I also replaced all the clear fuel lines and I found that at the back of the engine where the clear return line attaches (sort-of under the top of the intake manifold) the clamp had been broken long before I owned the van as well as the clip on the line that goes from filter to the LP pump (I broke that one). I also repaired a leaking HP pump at this time. Once I did all this no more air in the lines. Started right up at 4F this week. I would start with the water-bleed valve... unlike others my WIF sensor was not the culprit. Next time I change the filter I will use a Mann and see if it makes a difference.

Hey thanks guys glad I am not (even close to being) alone. And I can leave WIF sensor plugged into harness to fool the light. Win win. Tomorrow I will mess with drain valve and see what I can figure out.
Thanks!

Ok men I thought I would give update, this may be good info for future searchers. Yes, the drain valve was culprit! Thanks Blue! I removed filter from van, removed WIF sensor, it gave a loud Poof and then fuel poured from filter, this confirmed my suspicion that it was sealing good there. Screwed drain valve every which way, still couldnt get it to seal. So i gooped fuel-resistant sealer on WIF sensor and drain valve, let cure for day or so, then reinstalled filter. Bled it and No Bubbles! Been driving it for couple of days, no freaking bubbles in lines! I did go ahead and order a filter with no drain and WIF, thank you Nelson, and you are quite right, impossible to find in US at brick and mortar store.
Thanks for the help guys! No more bubbles! Yay

Just out of curiosity who manufactured the filter you are using now?

I ask because the bleed valve is used from filter to filter so this could be a weakness with aftermarket filters. Maybe the insert for the bleed valve is just a little "off" compared to the Mann filter.

I once had the water drain leaking air because it was TOO tight, which deformed the side of the filter enough to prevent a good seal.

For what it's worth my Merc mechanic advised me when I replaced the fuel filter to go for the one without the water drain cock. I used a Mann WK842/13 ........'06 T1N.

Rob

John484 said:

Guys I am so damn sorry for another air in fuel line thread. But this has been plaguing me for a month. It's an '03. I couldnt get the Water in Fuel light to go off, so decided to install new filter. I have been having air problems so I paid attention to the fittings on the filter when I swapped it. I put a new oring on the WIF sensor; it seems nice and snug. The oring on the new filter where the Clogged Filter sensor( isnt that what it is?) mounts is nice and tight. I purchased a new fuel line from the filter to the LP pump as the previous owner had broken the connector(shocker, I know). Basically, all of my connections seem good. I hooked my MityVac up to the line returning to the Clogged Filter sensor and am getting a nice vacuum, but there is still air in the damn line. Where is it getting into the filter? The water drain appears airtight, but then again my eyes are not a pressure gauge, lol.
Any tips for sorting this out would be appreciated. I have read most of the threads regarding air in lines, but I am still at my wits end. I have some choice words for Mercedes engineers.
Oh, and to top it off the WIF sensor plug wont connect properly so that is why my stupid WIF light was on, and will remain on apparently.
Thanks!
J

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I have a stethoscope that I have used to find my air leaks around my filter. Everything *looked* good, but the stethoscope allowed me to hear where air was being sucked in.
After having too many problems with the regular fuel filter, I ordered one on ebay without the WIF sensor hole. So far, it's worked well for me. 10k miles and counting...

While we're on the ever-present air in fuel topic again...
My low fuel pressure light showed up Friday on a trip over to the coast- I recently got an Ultragauge and was downshifting to 4th for the steady climbs in the coast mountain range, so was probably at higher rpm than normal. The light came on, so I pulled over and looked at the manual and at the fuel filter. I just happened to have direct sun on the fuel line, and sure enough, air bubbles. I was also getting a running-on-fumes type power loss around 3000rpm- some form of LHM? The light stayed on the rest of the drive over the hill (I did not shut the van off), then was gone on re-start and did not recur. The van (mostly) started fine since, although I've been chasing around an as of yet undiagnosed imtermittent start and stall for a while that occured once or twice today. But, I did run the rpm up around 3K a bit today and failed to get the fuel pressure light to come back. My theory is that on Friday the increased suction from the higher engine rpm (and thus, for us 612ers, higher low pressure pump rpm??) caused a very minor air leak to worsen to the point of indicating a pressure problem. Am I way off here, or has anyone else seen an air leak show these symptoms?
I'm about ready to make the filter switch to eliminate the WIF and drain plug... but out of curiosity, has anyone out there actually ever had to drain water from the filter? I sure haven't.

I haven't seen it, but it seems to me an air leak could result in low fuel pressure (mine runs rough and low on power right after a filter change when air is being eliminated). My low pressure fuel system is original (lines, fittings, O-rings, etc.) and I haven't yet had a problem with air leaks, so the OEM system can be durable. IIWM, I'd chase the leak and fix it so I could retain the OEM system.

A hayes, I have had nothing but bubbles in my lines the past month and I didnt notice any difference in the way it ran(once it was running that is) nor did it throw a low pressure light.
Blue, the writing on the filter degraded so that I cant read it, sorry. I was trying to save it so I could hate on it for awhile but it got rained on.

talkinghorse43 said:

I haven't seen it, but it seems to me an air leak could result in low fuel pressure (mine runs rough and low on power right after a filter change when air is being eliminated). My low pressure fuel system is original (lines, fittings, O-rings, etc.) and I haven't yet had a problem with air leaks, so the OEM system can be durable. IIWM, I'd chase the leak and fix it so I could retain the OEM system.

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FWIW. I agree with all TH43 added.

I've mentioned a couple times that I notice my 2004 (with in tank fuel pump) takes just a couple more turns to fire up for a while after I change my fuel filter. I'm convinced that it is air in the high side system which eventually purges out over time.

Entrained air can affect the high side fuel system (and of course the fairly common OM612 no sucking fuel start problem). That said, I don't think that it is common for people to post comments about the low fuel pressure dash indicator (which is only included in the NAFTA 2001 - 2003 OM612 fuel system) coming on after a fuel filter change or when there have been air leak problems. It has been posted quite a few times that a dirty filter can light that low pressure indicator. So maybe you have something clogging your fuel filter prematurely? A suggestion, not a diagnosis. vic

Edit: The pump on/off is easy and not messy at all. Bleeding or pre-filling (some OM612 owners pre-fill) the OM647 fuel filter is not necessary at all (or necessary for any Sprinter with an in tank fuel pump). Thanks for the suggestion though. That was for Showkey.

Just crack the bleeder on top of the filter after you change it. Then turn the key to run and watch fuel squirt all over the place. Or just run a hose from the bleed nipple back to the fuel filler inlet. Instant prime. On the subject of nipples, I don't trust anything that bleeds for 7 days and doesn't die.

shortshort said:

Just crack the bleeder on top of the filter after you change it. Then turn the key to run and watch fuel squirt all over the place. Or just run a hose from the bleed nipple back to the fuel filler inlet. Instant prime. On the subject of nipples, I don't trust anything that bleeds for 7 days and doesn't die.

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To hopefully clear up some confusion here- I think this will only work on '04-'06 T1Ns (tank mounted elec fuel pump). '02-'03s with the OM 612 motor do not have a fuel pump in the tank, so no fuel is moving until the crank is turning and driving the mechanical low pressure pump on the front of the engine. So I think if you crack the bleeder, it's just one more place to suck air into the filter. But I've been wrong before...

Thanks all for the suggestions on the low pressure light- I have not been able to get it to come back on again, so at this point I'm going to wait and see a bit. If it doesn't return I may hold off for a little while on the filter replacement (current one is only at 12K mi).

That was for vic

Just a heads up on the subject of the fuel filter change. I had changed mine and all went well until on start up the engine was a bit rough. So as stated in the manual I decided to bleed the filter. Opened the bleed valve and saw there was air bubbles but as I watched the fuel and the air bubbles were sucked into the filter. Tried several times to start but no luck. Problem was I was parked on a slight slope and the fuel was running back to the tank. Rolled on to the flat level and few minutes of cranking away she went. Continued with bleed and no further problems.
Moral of this, only change the fuel filter on these OM 612 engines on the flat or with the front of the van slightly down hill. Hope this helps someone one day.
Many thanks to everyone that contributes and responds to this forum. It has helped me a lot.
Regards to all.

Mikezb said:

...
Moral of this, only change the fuel filter on these OM 612 engines on the flat or with the front of the van slightly down hill. Hope this helps someone one day.
...

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Another thing that is said to help is to have a full tank of fuel when you change the OM612 filter. That isn't important for the OM647 or other engines that have an in tank electric fuel pump.

vic