underwoodtransp

I need a new pressure relief valve in my truck (have needed one for months now) and the dealer is having a hard time finding one and also hard time getting dc to let one go. I had asked my diesel tech (a good friend) if my box was the cause of my valve failure. He told me it probably was but "he has never seen any performance equipment on my truck" so he would get one for me. I am wondering what happens if another 50k down the road mine gives up again what do I do, keep replacing them? I talked to the dealer and found out they cost $455.00 so its not something cheap. Can I get an aftermarket one??? What are you guys with the high hp trucks doing to this valve to keep your pressure in the rail so that you can use the extra fuel. Any help is very much appreciated!!!

PourinDiesel

How do you know you need a new valve?

abc4yew

under, I think my diesel shop stocks them. PM me and I check it out for you. ks

JIMCTD

Has anyone here worked with these? Wondering what the ramifications (no pun intended) would be if a stiffer spring was installed on the valve, allowing fuel rail pressure to climb a bit higher without popping the valve? Any idea what max pressure the rail and injectors would tolerate safely?

PourinDiesel

Just raise the pressure until you see a fuel line split right down the middle then back it off a half turn....

mikmaze

but if he only backed it off a quarter turn then he coul put in presure washer tips in place of the injectors and still have enough presure to make a nice fine mist...................

king d

if you can get what looks like a helo coil out of the relief valve you can srew it out and put a small shim in place which will stiffen the spring and raise the pressure,for both huirt and unhurt valves

CTDHokie

I think read somewhere that the Duramax guys are doing this.

Don M

We tested a bunch with the rail over 33,000 PSI.

Never a broken rail, but injector bodies go bye bye pretty fast. The Bosch nozzles crack too.

Don~

JIMCTD

Don - Were you able to define a safe maximum pressure for the injector bodies and nozzles? Or is the factory setting on the relief valve the true max?
I'm not asking with the intent of adding a ton of pressure, just enough capability to allow a pressure box to run without popping the valve. If the valve is set to pop at 26K psi, then I was thinking around 29-30K for a rig running an Edge, VA, or other pressure box. If this solution is hopeless, then it's hopeless - but I can't find definitive figures anywhere to make that determination.

underwoodtransp

Back when I cracked an injector the tech did a leakdown test with the dc scan tool and set the pressure to max (25k) and watch if it falls actual pressure. Mine fell to about 20100 psi. He said it needs a new one. oh by the way dc's part number for the valve is (5093113AA) with a list price of $455.00.

Smkndzl

the one's in our trucks are 1600 bar valves , the one's in the 6.7 off road Cummins CR engines have 1800 bar valves, and the 6.7 Cummins road engines may come out with 2100 bar valve in end of 06 . now the engines with the higher pop off do have thicker injector lines and common rail.

nickleinonen

hmm... but will they cross over to our engines??? [the 6.7's i believe all have the rear geartrain so the inlet line might not match well???]

Don M

Well, the nozzles and the bodies can crack at stock pressure levels. Anything over that is a risk for long term.

The valve does not just sit there and open at a MAX value. It is dynamic and is begining to open as low as 1500 BAR. Depening on how quickly the rails pressure is rising.

The pump naturally can overrun the valve. This is to control heat in the rail by a bleed off of fuel as the engine operates. The valve constantly opens and closes. Unless you destroy the valve by ramming pressure at it too hard and too long.

The DMax guys began to shim on the LLY trucks for other reasons than low pressure, although the DMAX runs a lower pressure than the Dodge/Cummins to begin with.

I would not adjust the shims at all. Yes, you can do it, but the gain is small and the replacement parts are expensive. YOu dont gain durability at all. You may bring the valve back in spec for a short term, but the spring is just getting more stress.

We did rail pressure testing for durability of nozzles. Nothing else. BTW, the ultra high pressure ( over 30,000 ) did not make any more power than a setting over stock values in nearly all cases. Just more wear and tear. Duration and mild pressure works best, IMO.

Don~

JIMCTD

Thanks Don - sounds like this COA isn't very prudent. Quad tells me that his box comes nowhere near the 25-26K mark, so I have no issues now. Did have some with a VA pressure box awhile back, though, hence my curiousity (sp?).
Any updates on your 04.5 and newer injectors?