Are you interested in an adjustable IP fuel pressure relief valve? - Page 2 - PeachParts Mercedes-Benz Forum

Stretch · #16 09-30-2010, 03:04 AM

I am interested in this - however I have to be honest and say that I haven't a clue about the fuel system on a OM617. I'm still trying to figure out exactly how the basic system works. I'm still quite new to this.

I guess this could be a reason why everyone has not been hammering down your door funola.

Can you direct me (and perhaps others) to some good diesel injection systems for newbies / dummies threads?

4thesporty · #17 09-30-2010, 08:44 AM

Would this work on cars such as mine with the non adjustable spring?

scottmcphee · #18 09-30-2010, 10:02 AM

Don't understand why adjustability is required for anything other than spring fatigue over time.

Don't see the need to overpressure the fuel in the IP, either there is enough pressure to deliver the volume to the delivery valves, or not. So long as there is enough pressure, the valves are full and you get a full charge down the line.

Once the critical pressure is met, what does the extra pressure buy you? Nothing. It can't possibly increase the flow to the injectors. It can't possibly change your MPG or power.

To get the critical pressure, just replace the original spring, or stretch it a bit, as per FSM.

None of the poll options have what I'd vote for, so I didn't vote.

funola · #19 09-30-2010, 10:03 AM

Army, you're no newbie with all the work you've done. I don't have any links to good threads on the inline pump but a search should turn up a lot.

4the sporty, it is a direct replacement of the non adjustable. As a matter of fact, it is a modified non adjustable and I would need your's as core, if I was actually going to make them.on a continuing basis.

#20 09-30-2010, 10:18 AM

Quote:

Originally Posted by scottmcphee

Don't understand why adjustability is required for anything other than spring fatigue over time.

Don't see the need to overpressure the fuel in the IP, either there is enough pressure to deliver the volume to the delivery valves, or not. So long as there is enough pressure, the valves are full and you get a full charge down the line.

Once the critical pressure is met, what does the extra pressure buy you? Nothing. It can't possibly increase the flow to the injectors. It can't possibly change your MPG or power.

To get the critical pressure, just replace the original spring, or stretch it a bit, as per FSM.

None of the poll options have what I'd vote for, so I didn't vote.

I also do not understand how this would provide any benefit over a correctly adjusted IP.

funola · #21 09-30-2010, 11:38 AM

It's raining here and this was taken under an overpass, noise you hear is vehicle traffic. I am pumping the tire pump and you can see as I turn the adjustment screw c.w. the pressure increases. The gauge goes from 0 to 30 psi.

CLICK TO PLAY!

funola · #22 09-30-2010, 11:42 AM

With the adjustable relief valve at 30 psi, I am turning the adjustment scew CCW and the pressure decreases accordingly. Still have to install it into the IP and make sure there are no leaks through the o-ring.

CLICK TO PLAY!

whunter · #23 09-30-2010, 11:50 AM

Quote:

Originally Posted by Army

I am interested in this - however I have to be honest and say that I haven't a clue about the fuel system on a OM617. I'm still trying to figure out exactly how the basic system works. I'm still quite new to this.

I guess this could be a reason why everyone has not been hammering down your door funola.

Can you direct me (and perhaps others) to some good diesel injection systems for newbies / dummies threads?

Sending you a PM with links.

.

Stretch · #24 09-30-2010, 02:20 PM

Quote:

Originally Posted by whunter

Sending you a PM with links.

.

Thank you very much. For those who may want to know more Wikipedia gives a great overview

http://en.wikipedia.org/wiki/Diesel_engine#Early_fuel_injection_systems

The links that were kindly sent by whunter were:-

Fuel Delivery:
Diesel Fuel Delivery:

Diesel Injection:
Diesel Injection:

Run away diesel, why does it happen?
Run away diesel, why does it happen?

Engine blow-by test, Blow a bag of blow-by
Engine blow-by test, Blow a bag of blow-by

Blow-By curioisty questions
http://www.peachparts.com/shopforum/diesel-discussion/188320-blow-curioisty-questions-2.html#post1798266

Diesel TURBO issue Links thread
http://www.peachparts.com/shopforum/diy-links-parts-category/229542-diesel-turbo-issue-links-thread.html#post1929856

Engine oil cooler and hose/line issue, link thread
Engine oil cooler and hose/line issue, link thread

Valve adjustment OM615, 616, 617 FYI.
Valve adjustment OM615, 616, 617 FYI.

Sorry to go off on a tangent funola - I'll say no more!

Stretch · #25 09-30-2010, 02:24 PM

Quote:

Originally Posted by funola

With the adjustable relief valve at 30 psi, I am turning the adjustment scew CCW and the pressure decreases accordingly. Still have to install it into the IP and make sure there are no leaks through the o-ring...

It looks good - when are you planning to fit it on your car?

barry123400 · #26 09-30-2010, 03:44 PM

Higher than 19 pounds fuel pressure may be better with vo use. The viscosity is just heavier than diesel. You are attempting to get an element fill equivelent to the 19 pounds with diesel fuel use.

Checking the milli volts properly at different pressures should enable you if possible to balance the engine better. Equal fuel injection at all the injectors is where you want to be. Overpressure does produce yet better power. This area has suspected unknowns on diesel fueled cars.

If the current gentleman has a meter to measure the milli volts at various pressures it may show one of the effects I am talking about.

Some doubter should ask him if he is going back to the twelve pound pressure he originally had. I believe he will tell you there is no way that is in the cards. He has seen and experienced the differance..

funola · #27 10-01-2010, 08:39 AM

Quote:

Originally Posted by Craig

I also do not understand how this would provide any benefit over a correctly adjusted IP.

To have a correcly adjusted IP, amonst the many "adjustments", one of them is to either replace the tired pressure relief valve with a new one, or use my adjustable pressure relief valve. Last I heard new ones are NLA.

funola · #28 10-01-2010, 08:41 AM

Quote:

Originally Posted by Army

It looks good - when are you planning to fit it on your car?

Hopefully tomorrow.

whunter · #29 10-01-2010, 12:00 PM

Quote:

Originally Posted by funola

Last I heard new ones are NLA.

0000747284 Diesel fuel return valve/banjo bolt
0000747284 Diesel fuel return valve/banjo bolt

Have a great day.

funola · #30 10-02-2010, 10:43 PM

Installed the adjustable pressure relief valve today. It works! I can vary the fuel pressure up or down by turning the socket head cap screw and lock it down with the nut. The socket head cap screw I used is too long and does not lend well to using a hex bit since the temp sender in the head is in the way and the block too close not giving much room to work with. I will use a shorter bolt with a hex head on the next one and that should make it much easier to adjust. I want to put more miles on to make sure it is leak free. I have a white tissue wrapped around it right now and will inspect it in a few days- hopefully dry.

View Poll Results: Any interest in purchasing an adjustable fuel pressure relief valve?
interested in purchasing adjustable fuel pressure relief valve	17	80.95%
interested in renting fuel pressure tester	3	14.29%
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Multiple Choice Poll. Voters: 21. You may not vote on this poll