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#76
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Quote:
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#77
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The car never had any issues starting. It was very sluggish at higher rpm's, so I began cleaning the fuel system and found it to be extremely filthy. I have removed and cleaned the tank, replaced the tank strainer, replaced the spin on filter, and replaced the pre filter screen.
The car seemed to run exactly the same, even with a substantially cleaner fuel supply. I was driving at 40mph and it suddenly died, and would not restart. I found a ton of exposed wires, and decided to replace the entire engine wiring harness. Still a no start. Currently the intake manifold is removed for cleaning.
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95 E300 D 235k |
#78
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Recycled
to answer a member question.
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ASE Master Mechanic asemastermechanic@juno.com Prototype R&D/testing: Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician. Noise Vibration and Harshness (NVH). Dynamometer. Heat exchanger durability. HV-A/C Climate Control. Vehicle build. Fleet Durability Technical Quality Auditor. Automotive Technical Writer 1985 300SD 1983 300D 1984 190D 2003 Volvo V70 2002 Honda Civic https://www.boldegoist.com/ |
#79
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606.910 Fuel Pressure Relief Valve
I am looking for a solution to solve the FPRV problem stated here if someone has found a solution. Tried to correct the problem pointed out in this thread and here is what I found: W123 or W126 FPRV does not fit on the 606.910 injection pump the 123 FPRV is 23mm long while the W124 valve is 33mm long. The length is necessary for the banjo bolt to reach the threads which are recessed in the W124 IP compared to the W123 and W126. Mercedes has gone to the sealed design for all FPRV's W124, 123, 126 they did not even bother to change part number or state that part was superceeded. There are no longer any adjustable valves available from Mercedes. The only ones out there that I know of are used from the junk yard. Attached Thumbnail |
#80
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Has anyone checked the Tork Tec web site?They have a adjustable bypass valve for the Cummins Dodge trucks. They open around 20psi.
Tom |
#81
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You can close off the return line as a test. This takes the possibility of an open relief valve out of the equation.
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#82
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Just want to add a couple of data points and observations on the subject of the bypass valve springs.
My motor is 617.952 in very good condition and daily use; 377K miles. I have a spare bypass valve from another 617 motor. Bosch 1 417 413 012 This was a curiosity-based experimentation with a slight hope of achieving some degree of better performance out of an otherwise very good running motor. I disassembled and measured the spring of the spare bypass valve. The valve looked well used and quite dirty inside. The spring length was 20 mm. Eventually I examined the spring from the running motor. The operating spring also measured 20mm. The operating valve was pristine on the inside. What caught my eye was the difference between the two springs. The spare consisted of 10 coils, while the operating spring had 12. The spare felt a bit lighter on compression force. Both valves had the same Bosch number. I stretched the operating spring to 23mm, reassembled and tested motor operation. I noticed a _possible_ slight increase in the power, but nothing radical. Whatever improvement in power ensued was offset by a rougher idle and what seemed during a short (10 minute) test drive to be a bit harsher AT shifts. Aside from the rougher idle, the power increase and shifting harshness could be completely subjective impressions during a hyper-vigilant observation session. Improvements were negligible, degradation noticeable. I decided to return to baseline. I returned home, removed my operating spring and attempted to recompress is to former length. This is a finicky operation, but not impossible. Both ends of the spring have to be gripped (by small pliers) and twisted toward the winding center. Eventually I achieved 21mm and decided to test at this length. This time, the rough idle went away and the slight increase in power remained. I have decided to stop the test and call it good. …I found this thread after my own tests were completed, but noticed someone’s earlier report of a 21mm measured initial length of their own spring. For those on the path of experimentation, and without the proper return line pressure testing, I would say be careful with the 26-27mm spring length indicated in some posts and MB service literature. Curiosity aside, the fuel delivery tuning should start well downstream of the bypass valve and include the tank strainer, filters and lift pump valves first. |
#83
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Good post and gives many reasons why a pressure gauge should be used. I almost suspect your increased spring tension relief valve was not opening anymore. .
The relief valve was then staying closed and the cigar hose was no longer in the circuit. This could roughen up an idle. The proper way to test the system in my opinion is get a gauge in the circuit. Read the existing pressure. Close off the return to establish how much real pressure the lift pump is or can deliver. Then decide what needs done based on the two readings. I also suspected there were two different lengths of springs when new. Never could prove it though. When checking fuel pressure it is nice to have a new or recent secondary fuel filter in the system. An old filter can become restricted enough to drop the pressure in the base of the injection pump. |
#84
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Googling the Bosch 1 417 413 012 gives you this link:
www.monark-automotive.com/netstore/pdf/a2052-00.pdf It is clear that the bypass valve is designed with an operating range between 1.0 and 1.5 bar I am sure there are lots of variables in any old 617.xxx, but if the 27mm spring "fixes" the performance of an otherwise stock car, the heavier or stretched spring is just compensating for some other problem. It would be interesting to find out from others what their unmodified stock spring length is. I've heard of 21mm and personally observed 20mm twice. |
#85
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Stretching the spring is returning it to it's original length and relief valve pressure opening point. Going beyond that does many things and the cars usually tolerate it well within reason. Almost always it makes the idle better certainly not worse if it does not.
I suspect something is going on with your example. It could be a few separate things or combination of them. Basically normally increased fuel pressure seems to fill the elements a little better. Substandard pressure seem to also fill them unequally to some extent. Denying you a balanced fuel delivery from all injectors at the original intended injection pump sequential timing. |
#86
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Does anyone know what size the bolt is for the return valve? I'm sizing up different ways to try and get to it, has anyone removed it without taking off the intake manifold? I have the om602.
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1993 300d - Von Strudel 1987 190e (RIP) - Duke 1983 230e (sold) - Helga 1982 240d (sold) - Igor 1973 280 (sold and missed ) |
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