(08-21-2012, 03:18 PM)Hercules Thanks for sharing;good write-up. Would a electric pump near tank solve this problem? Lift pump pressure jumps wildly on the 617,616 and others also. WHY not a steady flow,at least on the pressure side. Dropping from 1 bar pressure to zero with every stroke of the pump. Was this in the design??? Is there any way the fuel to inter the oiling system in the injection pump?
If not, a electric pump could be a good up grade,(improved performance). Although the old stroker pump is dependable.
Looking for answers (not guesses )

(08-22-2012, 04:57 AM)mantahead hi fuel thermostat is:

at top inside diameter 12mm
at side (where rubber pipe pushes on) inside diameter 6.8mm

Although it is 12mm the inside diameter of the pipe going on there is 6mm

(08-22-2012, 10:49 AM)AlanMcR

(08-22-2012, 04:57 AM)mantahead hi fuel thermostat is:

at top inside diameter 12mm
at side (where rubber pipe pushes on) inside diameter 6.8mm

Although it is 12mm the inside diameter of the pipe going on there is 6mm

Thanks!

So to be sure, the outside diameter of the hose nipple is 12mm and the inside is 6.8? 12mm seems a bit large, only because I managed to force an 8mm hose over it, all be it with a lot of grunting & swearing. Is that measured at the thickest or thinnest part of the nipple? The measurement that matters most is the diameter of the straight section of the nipple where the hose clamp is applied.

...Alan

(08-22-2012, 12:04 PM)mantahead hi,
no the one with the rubber hose is 10mm or 10.8mm at thickest point outside diameter.
the 12mm is the inside diameter of the other pipe with the plastic fitting.

(08-22-2012, 03:44 PM)mantahead hi,
i was talking to a parts man in a Mercedes dealership today about this issue and he told me:
over the years they had some problems with air bubbles in the fuel lines and some cars where hard to start if left overnight but they drove alright. Nine times out of ten the problem was the o ring behind the electric cut off valve on the side of the pump.
Almost forgot, on a few rare occasions some cars still had problems and there was a kit available which had some sort of pipe re-routing or something in it.

(08-25-2012, 05:21 PM)Alastair E AlanMcR--

Hope you dont mind, Ive copied this post onto a UK Veg-oil forum, where there's always someone bleating about air in fuel issues-(issue will be MUCH worse with thicker fuel, maybe with solvents added)
--Full credit to yourself and a link back to this thread here.

Here is the thread I started there--

http://www.vegetableoildiesel.co.uk/forum/viewthread.php?tid=33094

(08-22-2012, 01:37 PM)AlanMcR

(08-22-2012, 12:04 PM)mantahead hi,
no the one with the rubber hose is 10mm or 10.8mm at thickest point outside diameter.
the 12mm is the inside diameter of the other pipe with the plastic fitting.

Excellent! I just dug up a picture off for the benefit of anyone reading this thread later.

(08-26-2012, 02:36 AM)TURBO_DAN I have bypassed that bugger on my om606 G wagon,460.No more air in my fuel lines also they have been replaced with 8 mm new hoses from the tank to lift pump.Another good idea is to remove all O ring plastic lines with rubber ones attached to Stainless Steel Hose Nipple.This way I got only 2 rubber O rings left on my fuel system:1 on the fuel filter and 2 behind the shut off valve.In order to heat the fuel I have installed heat exchanger.

(08-26-2012, 05:01 PM)mantahead hi,
on my om605 drift car i used, electric inline pump near the tank which fed a twin filter housing of a renault truck. So, original lift pump and filter where taken off. Pipes where changed to 12mm nylon right to the tank.
I had nowhere to put the injector leak offs so i used a return banjo off a bmw 325tds which had the small fitting for the leak offs. This banjo was fitted to the return on the pump.
I was wondering, could i do anything to improve this setup?

(08-26-2012, 05:01 PM)mantahead hi,
on my om605 drift car i used, electric inline pump near the tank which fed a twin filter housing of a renault truck. So, original lift pump and filter where taken off. Pipes where changed to 12mm nylon right to the tank.
I had nowhere to put the injector leak offs so i used a return banjo off a bmw 325tds which had the small fitting for the leak offs. This banjo was fitted to the return on the pump.
I was wondering, could i do anything to improve this setup?

(08-28-2012, 07:55 AM)mantahead hi,
i have 2bar entering the ip.
Dont know the make of the pump, think its off a petrol fuel injected car.
The pressure is just regulated by the return banjo bolt.
One thing is for sure, it is so much easier to bleed the fuel system with electric pump feeding the ip.

(08-31-2012, 05:28 AM)tomnik Hi,

is this 2 bar under load or at idle/low load?
What is the pressure with WOT?

Tom

(08-28-2012, 07:55 AM)mantahead hi,
i have 2bar entering the ip.
Dont know the make of the pump, think its off a petrol fuel injected car.
The pressure is just regulated by the return banjo bolt.
One thing is for sure, it is so much easier to bleed the fuel system with electric pump feeding the ip.

(08-31-2012, 07:05 AM)mantahead hi,
it was 2bar at idle and then it would drop back under full load, can't remember exact pressure, i think a rising rate regulator would be best that increases with boost pressure, what you think?

(08-31-2012, 05:28 AM)tomnik Hi,

is this 2 bar under load or at idle/low load?
What is the pressure with WOT?

Tom

(08-28-2012, 07:55 AM)mantahead hi,
i have 2bar entering the ip.
Dont know the make of the pump, think its off a petrol fuel injected car.
The pressure is just regulated by the return banjo bolt.
One thing is for sure, it is so much easier to bleed the fuel system with electric pump feeding the ip.

(08-22-2012, 01:37 PM)AlanMcR

(08-22-2012, 12:04 PM)mantahead hi,
no the one with the rubber hose is 10mm or 10.8mm at thickest point outside diameter.
the 12mm is the inside diameter of the other pipe with the plastic fitting.

Excellent! I just dug up a picture off for the benefit of anyone reading this thread later.

(10-25-2012, 01:41 PM)Olivier Is it a EDC 606 pump you are using Hansebanger? If yes, what valve did you use?
Cheers.

I have installed a non return valve on the Return, on the filter head, it help a bit as its a little restriction and the fuel stay a wee more under pressure as its recirculated back in the pump, I thought I may add this too

On the 606 W210 there is a big restriction on the filter head, right after the pre-filter. I think it go down to 6mm there. I drilled mine long ago on the first E to get better flow.

(08-21-2012, 12:33 PM)AlanMcR I thought I'd post some things I've discovered about the OM606 fuel system. You folks are always interested in performance issues and this is a basic design flaw in the MB implementation. While this is a bit of an oddball case (OM606 in a G-wagen - WDB46333117106xxx), the issues also apply to the OM606 in the E-class and probably in the S-class, too. The underlying issues are probably applicable to a wide range of inline IP pump diesels.

What got me going on this was the the engine had poor power and ran just a little rough past about 2800rpm. There was one exception though, and that was when the fuel tank was full, right up to the lip. The other clue was that one could see bubbles in the clear fuel lines whenever the engine was revved up (out of gear).

The answer is that A) the fuel system was poorly designed (by Bosch); and, B) not even built (by MB) the way it was designed. This gets to be a long story, but the basic problem is that the lift pump pulls so hard that it pulls gasses out of the diesel fuel on its intake stroke. Those gasses do not diffuse back into the fuel during the delivery stroke (basic physics). Once the bubbles form, they are in the system for a long time. This is because getting gasses out of solution is much easier (and faster) than diffusing a large bubble back in to the solution. The bubbles are large in the line before the fine fuel filter and get chopped into 10 micron bubbles by the filter. The tiny bubbles are harder to see, but they are still gas bubbles and haven’t recombined into the liquid. Since they are compressible, when the IP plunger starts delivering fuel it first has to compress the bubbles to the injector opening pressure, that introduces a delay in timing. Also, since part of the chamber was filled with gas, that effectively reduces the total fuel delivery. Both problems reduce power.

Background: The diagnosis took a while. As I said earlier, I’ve noticed bubbles in the line going to the fine fuel filter at elevated RPM’s. I always assumed that the problem was due to air sneaking past the o-rings. I believed this even though the leaks continued with fresh o-rings. How wrong I was.

Recently, while doing some work with the intake manifold off, I decided to run an experiment. I installed some clear soft 8mm Tygothane tubing in place of the line going from the tank to the fuel heater/thermostat. There were no bubbles in the line. In fact there were no bubbles anywhere in the system. Aha! I said. The fuel line must have been leaky. I did notice that the soft clear line was pulsating wildly with each stroke of the lift pump. Just for fun I squeezed the line with my fingers to see if that would kill the engine. As I started to squeeze the line, a foam of bubbles appeared in the flow just after the pinch spot. Clearly the tube wasn’t leaking. Rather, the suction of the pump was lowering the tube pressure below the vapor pressure of diesel fuel. Thinking about this more, I realized that the reason that the bubbles had disappeared was because the pulsating line was providing pressure stabilization. So, the conclusion is that pressure (or rather vacuum) pulses are the cause of the bubbles.

Now for the design mistakes. The OM606 has no hand primer. Bosch needed a way to self-prime the system before the battery died. They chose to increase the volume of the lift pump and re-design the overflow return valve. In the past, the valve was designed to maintain a minimum pressure in the IP. In order to self-prime, the OM606 valve was re-designed as a simple one-way valve with a rather large opening. It prevents fuel from flowing backwards, but provides little flow restriction. The pump and valve together can move a lot of fuel, more fuel than the old fuel lines were designed for.
“No problem”, the Bosch engineers said, “we’ll just make the fuel line bigger”. They made the inlet to the fuel thermostat ~10mm rather than the old 8mm. The larger pipe will flow 56% more fuel. What could go wrong? Well, the MB bean-counters got in there and managed to make it go wrong. To save money, they installed an 8mm hose with a ~10mm bulge at the end. Worse, they connected this to a thick walled fuel line that is <6mm in the inside and almost 3M long. The steel line only flows ~36% of the intended Bosch design. That restriction is enough to ensure massive pressure pulses. Ooops.

Technically, a 6mm ID tube would flow the required 3lpm. But only if that flow were smooth. Unfortunately the flow is driven by a piston pump at 1/2 RPM and it is definitely not smooth. It is the pulses that cause the vacuum and thus the bubbles.
This design is present on the E and G. The problem is made worse on the G, because the fuel needs to be lifted up ~20cm, even on flat ground. The G always ran better if I filled the G up all the way to the edge of the opening. After the first liter was burned off, performance returned to “normal”. The extra performance was because fuel was being pushed into the fuel line, rather than pulled. On a steep upslope this is, of course, even worse.

At altitude there is another phenomenon. Since the fuel system is a suction system, the only reason that fuel flows is because the pump inlet is at a lower pressure than the tank. From a basic physics perspective, air pressure in the tank is pushing the fuel into the lift pump. As you go higher there is less and less air pressure pushing on the fuel. So, all the problems listed above just get worse. On my G the problem can be severe at >3000M. With a low tank at 4000M the fuel line is full of bubbles and it hardly moves at all.

Simply because I had it handy, I installed a long 8mm hose all the way to the tank, eliminating the steel line. This noticeably improved the performance, particularly in uphill passing.

Request: Does someone have a OM606 fuel thermostat in hand? I'd like a verification of the inlet neck measurement. I recall 10mm, but it might have been 1mm larger or smaller. I don’t want to take off the manifold just to measure that. I need the measurement at the neck not the bead.

(04-19-2014, 12:46 PM)yorkshire1 thought Id experiment with the OM605 electronic pump plumbing today by pressurizing rather than having the clear lines under vaccuum/ suction as Ive been having intermittent air ingress after throttling off then accelerating again

basically took feed straight to lift pump then up to thermostat and back to the immobiliser valve then to filter (prefilter is bypassed)

problem is that this re-routing has resulted in the EPC light coming on with resultant power reduction as I believe it must cut turbo boost signal

I then connected another immobiliser valve I had as a slave to my existing electric socket with the same result, car starts and runs fine but as above EPC on and power reduction

can anyone shed any light on what it is thats throwing the code

my next option is to loop /blank 2 of the valve ports

(04-21-2014, 06:16 AM)Druk I have my fuel plumbed from the tank through a Lucas.CAV primary filter/ priming pump on the inner wing then to the lift pump then to the OE filter then to the IP. I cut out the thermostat heater thingy and the OE primary filter which doesn't seem to have any negative effect on the fuelling.

(04-25-2014, 06:56 PM)AlanMcR The immobilizer solenoid has two jobs.
1) it cuts off fuel flow
2) it measures fuel temperature.

If you disconnect it then the ECU will get unhappy. If you connect it, but leave it hanging in the engine compartment without fuel flow, then it will probably be upset by the measured fuel temperature being wrong.

(04-27-2014, 06:16 AM)yorkshire1

(04-25-2014, 06:56 PM)AlanMcR The immobilizer solenoid has two jobs.
1) it cuts off fuel flow
2) it measures fuel temperature.

If you disconnect it then the ECU will get unhappy. If you connect it, but leave it hanging in the engine compartment without fuel flow, then it will probably be upset by the measured fuel temperature being wrong.

appreciated they are its recognized functions however it seems its also pressure sensitive as it lights the EPC light if fed from the lift pump

(04-27-2014, 09:42 AM)AlanMcR

(04-27-2014, 06:16 AM)yorkshire1

(04-25-2014, 06:56 PM)AlanMcR The immobilizer solenoid has two jobs.
1) it cuts off fuel flow
2) it measures fuel temperature.

If you disconnect it then the ECU will get unhappy. If you connect it, but leave it hanging in the engine compartment without fuel flow, then it will probably be upset by the measured fuel temperature being wrong.

appreciated they are its recognized functions however it seems its also pressure sensitive as it lights the EPC light if fed from the lift pump

Having cut one open, I can assure you that is all that it does.

(04-27-2014, 02:13 PM)yorkshire1

(04-27-2014, 09:42 AM)AlanMcR it begs the question what it is about that valve thats putting the epc light on then as the only difference is that its under pressure and not suction