functions of cascade valve?

[Walcott]

Trying to understand function of casacde valve on cp3,how would one know if it's not working properly?

 

[hunterdiesel]

Functions of Cascade Valve

This is probably the best explanation of the CP3 pump.

CP3 and Fueling System Explained - Dodge Cummins Diesel Forum

 

[cerberusiam]

Regulating case pressure, supplying lube flow, and over pressure relief are its main functions. Failure could include but not be limited to:



Cp-3 failure



Low rail pressure



Inadequate rail fuel supply







Those are worst case scenarios. Minor changes are a lot harder to diagnose and attribute to the COV but it is a component that can have an effect.

 

[Walcott]

Thanks for your help,just changed injectors after 230,000 and did see a minor change but it still wasn't on. Found a blown PRV so that's on its way,what is surprising is the truck ran pretty good. Mileage was down to 13. 3 Avg city and power was way down.

Thanks again!!:-laf

 

[JJPage]

Regulating case pressure, supplying lube flow, and over pressure relief are its main functions. Failure could include but not be limited to:



Cp-3 failure



Low rail pressure



Inadequate rail fuel supply







Those are worst case scenarios. Minor changes are a lot harder to diagnose and attribute to the COV but it is a component that can have an effect.

Yes... . I am getting quite familiar with this small component.

 

[Walcott]

JJpage

what was your experience with your truck,is this valve a common faliure?

 

[TCDiesel]

The valve is robust, its fails for a reason,In most cases it will fail shortly after being replaced UNLESS the Problem is found,,,excessive pressure from lift system MAY reduce its LIFE considerably. In most posts HERE the DTR,CF,Comp (AT the Comp it is expected to post for HP) if you follow the advise you will destroy your injector(s),pump and wallet $$. Don't take this WRONG some really good advise exist Here and other Forums, YOU need to exercise discernment wisely. Example: someone may plugged their LV for more HP for some event,B/C He did this I should plugged My LV on my every Day driver?

 

[JJPage]

what was your experience with your truck,is this valve a common faliure?

I am not sure how common it is, but symptoms are similar to a rail relief valve or lift pump failure, low/unstable rail pressure, poor performance.



The cascade valve is spring loaded, and it operates to maintain feed pressure to the CP3, and from getting too high, it then bypasses the extra fuel back to the return side, but if I understand it correctly, it also provides lubrication/cooling to other parts of the CP3. I believe, just like the rail relief valve, the more it is operated the weaker the spring and more fuel is being bypassed.



If you look at it, it has a little disc in the plunger of the valve that the spring holds in position, this disc can get hung up, debris could keep it from closing(lack of filtration), or they just wear out. I am not sure exactly what the modified cascade valves entails, but part of it is stronger spring pressure, could be by shimming.



TWest has more knowledge about their purpose and operation, maybe he will explain more thoroughly , maybe?

 

[Walcott]

is it common if the PRV has failed chances are the Cascade valve would be weak also?

 

[cerberusiam]

is it common if the PRV has failed chances are the Cascade valve would be weak also?

Not really, they are on opposite ends of the pressure spectrum. The stock COV operates around 75 psi and we all know where the raill pressures go. Pretty hard to draw any relationships there.

 

[JJPage]

The URL hunterdiesel linked in post 2, really does explain the function best.



Just need to take the time to read, Thanks hunterdiesel.