On the 603 they are the clear lines with those banjo bolt fittings on the IP.

On the 606 they are all plastic, but cheap as dirt. Every once in awhile they leak. I think my friend last touched his a few years ago. The trick is to not bother them, if you mess with them they will leak. If you don't they seem to hold up all right.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

These are the fuel lines on the 606(962). http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=25L0RF04Y2G11EGYXW&yearid=1999%40%401999&makeid=MB%40%40MB%40%40X&modelid=E%2D300DT%2D001%40%40E+300+D+Turbo&catid=E%40%40Fuel+Delivery&mode=PA&subcatid=E5009@@Fuel+Line&source=www.peachparts.com&clientid=catalog.mercedesshop

Each end has an oring. The line fits VERY snuggly and "click" into place very positively. The lines don't usually fail although do get yellowed with age making it difficult to see if air is in the line or not. New lines are clear making it easy to find the air entry point. The orings do deterioate over time.

Over all makes it much easier to track down bubbles or froth than with the 61x or 601-3 engines. Although is prob more prone to air intrusion too.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Has anyone else here had the kind of issues which the OP had with his seals?

There is really no reason why he should see air in the lines after replacing the o-rings if everything else is intact. o-rings SHOULD provide an air and fuel tight seal, especially when brand new. I can say I never examined them the way he said to but the fact that mine never had any issues associated with air in the fuel or leaks leads me to believe that even if mine had bubbles they are benign, though, again, I doubt they exist in my car's fuel system.

I'd still say if he sees air bubbles in his lines after replacing the seals that it is getting in someplace else and that's where the effort should be made to fix it. Either the pre-filter o-ring, the shutoff valve o-ring or one of the fittings is bad. It could even be where the hard line and rubber hose connects that can cause this.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Yes, I have. I have new o-rings from fryerpower.

Part of my issue is that with my SVO conversion, I have much more of the system operating under vacuum. On the diesel filter housing, I tapped the aluminum for barbed fittings, so that part works fine. But I have had issues chasing down other air leaks.

Part of the problem is that when chasing air leaks, I've had the system apart a couple times. At this stage I recognize that I really should put a new set of o-rings in it. In fact, I'll order some today.

Either way, add me to the list of people who would embrace an improved method of hooking up fuel lines.

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Jake
1999 e300d PlantDrive WVO/SVO conversion
**note to self: oil changed at 268k kms**
1990 Toyota 4Runner FrankenDiesel swap

I guess I should have qualified my statement with "has anyone with a stock fuel system experienced the air problems of the OP?" because I would not want to even venture to guess how you start to solve problems in a converted fuel system. Once you alter the stock system you can't complain about its design, IMHO, you're kind of on your own.

I assume the OP's system is stock? Is that true or has he also modded his?

Edit: I have now re-read the OP more carefully. He's got a G300 with the same engine as our E300 but it sits higher...OK, now I see what his problem is...we were not comparing apples to apples...I should have read it right the first time and I would not have been so absolute in my condemnation of doing a conversion...sorry.

Now that I understand his situation this is what I would do...I would look into a small electric booster pump to place near the tank which would simply reduce the head that he's seeing at the lift pump. Something which just offsets the 2 feet of lift - maybe a couple of PSI is all that's needed to neutralize the effects of pulling the fuel up to the engine's height.

Here is an example of what I am talking about:

http://www.sell.com/23JR6T

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

True, but the fact is the om606 is prone to air leak issues even in stock form, compared to earlier cars that used more solid fittings like banjo bolts. Before I touched the fuel system, I vacuum tested it. Even with 1 year old fuel o-rings, I got noticeable air leaks from 2 locations at 8-9 inHG... that's not a lot of vacuum.

I don't feel uncomfortable stating bluntly that it's a poor design. A quick scroll through posts about the om606 demonstrated that it's pretty much the #1 source of trouble on the fuel system. It's one small issue on an otherwise fantastic engine. Not a huge deal, but certainly a PITA.

The fact that my car is converted only means that the tendency toward air leaks is exaggerated. Diligence and good workmanship keeps it at bay, but it would be great to have a better solution.

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Jake
1999 e300d PlantDrive WVO/SVO conversion
**note to self: oil changed at 268k kms**
1990 Toyota 4Runner FrankenDiesel swap

Agreed...I think it is the #1 achilles heel under the hood. What about trying the low pressure pump like what I suggested for the OP? It is much harder to get an airtight seal under vacuum than a fuel tight one under pressure. I'd bet with a couple of PSI of boost from the tank you'd be all set. You could even install it under the hood, right where the hard fuel line connects to the first rubber hose.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Are your white horseshoe clips on the ends of each fuel line installed loose and floppy, or pushed in tight currently?

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Not sure who was being addressed with the question. For my part: the white clips are loose. That is what allows the side latch arms to come in and hold plastic head into its hole. The G originally came with spring steel clips, but MB economized and moved to plastic clips on the newer hoses for the E. Ah, progress! The only thing this design did for MB is to reduce initial assembly costs.

Speaking of progress:

I mixed up some 48hr high heat epoxy last night. It has been applied to two spots on a plastic fuel line head. One spot was vigorously cleaned with 1-1-1 Tricloroethane the other surface was left just as it was when it was pulled from the engine. I swirled the epoxy around the site in both cases. After 8 hours I am unable to pry off the epoxy by thumbnail. Now to wait for full cure and then several cycles of >100C and <0C while bathed in oil.

My question was addressed to you.

You'd be surprised how many people with leaks are driving around with the spreaders pushed closed so it had to be asked.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

The booster pump idea has occurred to me too. If I did that I'd be tempted to remove the mechanical lift pump and just put in two boost pumps in parallel. Both mounted low, so as to self-prime. That would give me some redundancy as well as provide an automatic bleed of the system at every start. The downside is that the entire system would be under pressure, even if that pressure is low. Leaks could turn into flammable problems rather than side-of-the-road repairs.

I'm pretty convinced that a major contributing factor to leaks in the OM606 system is that the pulses of suction from the mechanical pump wiggle the o-rings around and accelerate wear. (Of course, if there were no o-rings...no...don't start that again)

BTW: while I'm discussing this with an eye towards my G. The E also has bubbles running around at >2500RPM. They just doesn't seem to cause that much of a problem in the E. The lack of performance impact may be due to the reduced draw height from the tank. On the other hand, there are few places where one could drive the E at wide open throttle for any length of time without wildly exceeding a speed limit

Diesel fuel (and VO/biodiesel) isn't anywere near as volatile as gasoline so you don't have to ever worry about a leak causing a fire. You can put a match out in it. Don't worry about having leaks under the hood if that is what keeps you from installing a pump at the tank and pressurizing the fuel system. I don't think you will have leaks with a 3-5 PSI pump at the tank anyway but even if you did there will be no fire if you get a leak.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

I decided to give the original hose design one more try. So, I replaced all the clear rigid hoses, complete with new o-rings, all straight from the factory. In the process I found that the SOV to IP O-ring was on its last legs. So, every O-ring is now new. After bleeding the system with an out board motor squeeze bulb the motor sprung to life remarkably quickly. But...

I still had bubbles, lots of them. The bubbles start at the exit from the coarse filter and before the SOV. (Yes, I got the filter O-ring, too). It was leaking something fierce there. I went back and checked the rings and the mating surfaces. Nothing obvious. It could be any of the three O-rings, a corroded surface, or perhaps even a porous casting. There is just no way of diagnosing it. So...

I bought some ether based 1/4"ID-1/2"OD braided clear Tygothane hose and made a jumper from the exit of the fuel heater directly into the SOV. This hose fits the plastic hose barbs perfectly and seals nicely with spring clamps. This hose is water clear (aside from the reinforcing braiding) so you can see the oil (and any bubbles). I bled the system again and fired it up. Now...

No bubbles! I can rev it up to scary speeds and ... no bubbles!

Of course now there is no coarse fuel filter, and that might chew up the lift pump over time. So, I found an OEM filter from Hebmuller (W0133-1641441) that fit nicely into the line going into the fuel heater. These are also clear so you can actually see how plugged your coarse filter is.

So that is the story so far. I'll be off-roading for most of a week next month. I'll be about as far as one can get from civilization in the lower 48. Hope it holds!

When did you last replace the oring of the shaft of the bolt at the main filter?

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Forgot to mention that. The filters (fine & coarse) and their associated o-rings got replaced too. The nice thing about the clear pipes is that you can see exactly where the air gets in. In this case that is in the area of the coarse filter.

Unfortunately the coarse filter has, effectively, 3 O-rings (inlet, filter body, and outlet). Distinguishing which was the source of the leak is near impossible and simply not worth the trouble. The solution posted above is simpler and easier to diagnose should it leak again or clog.