bypass valve question - Page 2 - PeachParts Mercedes-Benz Forum

weird beard · #16 09-16-2010, 02:56 AM

I just tried a cummins / bosch overflow valve for a vp44 injection pump. Does not fit. 14mm instead of 12mm.

funola · #17 09-16-2010, 08:51 AM

Quote:

Originally Posted by glenlloyd

Here's what I found in my Bosch In-line FI Pump Yellow Jacket book from '03 about the overflow valves.

While it doesn't talk about any specific pump it does suggest that restrictive pressure should fall somewhere between 30-43psi (2-3bar).

steve a

Interesting pic. The 617 valve does not have item 1 -ball spring seat.

Diesel911 · #18 09-16-2010, 12:48 PM

In the pic in post #17 item #1. Hunter said the new ones are like the pic. There is no screw on the end to get at the Spring.

In the manual they have the pressure of the Fuel Pressure Relief/Overflow valve as being 1.3 bar (about 18.35 psi) at 3000 rpm.
Idle 0.6-0.8 bar (8.7-11.6 psi).

Here is a test no one I have read has done. If you hook a Vacuum Gauge at the Lift/Fuel Supply pump inlet it supposed to pull 0.1 bar of Vacuum. If not it has you should replace the suction and delivery valve or the complete Lift Pump.

sixto · #19 09-16-2010, 01:10 PM

If you wanted to measure IP gallery pressure, would you tap into the line from the big filter to the IP?

Sixto
87 300D

Gillig · #20 09-16-2010, 05:30 PM

Any place after the lift pump will show system pressure.

barry123400 · #21 09-16-2010, 08:43 PM

Quote:

Originally Posted by Gillig

Any place after the lift pump will show system pressure.

Perhaps but pressure may start to rise as filters obstruct if installed before the primary and secondary fuel filters. Installed after the secondary filter will reflect what pressure is remaining as the filters obstruct.

Perhaps being more accurate at indicating the time to change fuel filters or locate why the pressure is sagging as time goes forward. Also we are watching for ideally 19 pounds pressure in the injection pumps base fuel supply. The filters between may tweak that pressure reading even if new a little. Still a gauge feed back there is better than no gauge at all and I might be splitting hairs.

barry123400 · #22 09-16-2010, 08:52 PM

Quote:

Originally Posted by glenlloyd

Compare the fittings if possible, the MB Bosch pump valve is 12x1.5.

I've come to the conclusion that the valve is important, but that the lift pump is more critical. If the lift pump isn't maintaining adequate pressure the pump will suffer because flow-through is insufficient for cooling requirements.

Personally I'm going to order the lift pump overhaul pieces before I attack the overflow valve.

steve a

If you install a gauge you can test the lift pump to see if it is time to kit it. Also check your existing base pressure in the injection pump to determine if you have work to do. In most cases there will be work to do.

Now that people have seemingly determined that tapping a fitting into a banjo bolt works well and is neat.I think diesel 911 was first. There really are not many issues.

How are you going to calibrate the relief pressure valve and verify the system is approaching nineteen pounds without a gauge installed? Determine status of your tank screen and in line fuel filters? For the price of the kit or little more to revalve the lift pump you can install a liquid dampened gauge.

compress ignite · #23 11-11-2010, 02:38 AM

EDIT: Spring found

THEY HAVE A PLASTIC INSERT and a ridiculously small SPRING!!!

Garbage!!!

Own a Mercedes OM60X.XXX engine? You have the same trash on the side of your I.P. !

Oliver Dis-Assembled his and this is what he found:

compress ignite · #24 11-11-2010, 07:53 PM

Online cross reference charts:

mcreynol · #25 05-11-2011, 07:13 PM

Did anyone come up with an replacement part for the OM606 overflow valve? I am in need of two.

whunter · #26 05-11-2011, 11:38 PM

Quote:

Originally Posted by mcreynol

Did anyone come up with an replacement part for the OM606 overflow valve? I am in need of two.

Use a valve from a 123 or 126.

funola · #27 05-11-2011, 11:46 PM

Quote:

Originally Posted by mcreynol

Did anyone come up with an replacement part for the OM606 overflow valve? I am in need of two.

I have 3 of these adjustable fuel pressure relief valves left. Send me a PM if interested.

mcreynol · #28 05-12-2011, 01:20 PM

The adjustable ones look a little short. I measure the OM606 Overflow Relief valve at M12x1.5 and 33mm long. I took mine apart. It consists of four parts:

The body, a plastic valve element, a spring and a BB to seal the back. Just plain junk.

The actual valve opening diameter is 3.5mm or 9,6sqmm.

I think the pump is supposed to operate at 15PSI. 15PSI equals .023lbs/sqmm, so the spring ought to have 9.6x0.023 = 0.223lbs of push. I can hardly hold the spring without it collapsing.

In summary: this is not a pressure valve, but rather a one-way valve. Mine didn't even do that. I had my suspicions when I was able to drive with pump inlet line clamped (fuel drawn backwards from the return line).

(edit): The plastic bit is backwards. The actual sealing face is the part shown nearest the spring in the picture. I think the plastic part was probably not so twisted up before the traumatic dis-assembly process.