Really newbie question about pump elements
 

Hi all,

I am about to ask a really newbie question and I apologise in advance, its concerning elements in the IP. I know that my stock OM606.962 engine has 6mm elements.

Here are my queries:

Am I correct to say that the elements are the parts sticking up on the top of the pump which connect to the individual fuel lines to the injectors?

Am I correct to say that the diameter of the hole the fuel flows through on my pump is 6mm?

Am I correct to say that there is a plunger inside the element which then gets pushed up by the pump internals which then sends the fueling through the lines?

Upgrading the elements from a 6mm to an 8mm element would mean that the element would have a 8mm diameter as well as matched with an 8mm plunger - or is it just the diameter at the top of the element that gets enlarged and you can run stock plungers?

I only ask as I know someone who is a machinist who has various lathes etc - I was wondering if it were possible to simply get a set of stock elements and modify them by enlarging any ports and then machining slightly larger plungers if needed?

Sorry for the newbie questions, I know that some people have done a DIY swap of the elements but all I can see is that the element is held at the top of the pump which might mean that if they are kept in the same order they might not need calibrating?

The parts sticking up are the delivery valves. They are a 32 spline fitting and they screw into the injection pump body. Below these are the elements.

I wouldn't think a local machinest could ever make pump elements. They are extremely EXTREMELY precise pieces of work. They control the fueling behavior of the pump.

If you want to upgrade the pump:
Remove it from the engine
Send it to Goran at Dieselmeken
He'll install bigger elements and recalibrate the settings
Reinstall the pump
Add more air with a bigger turbo to burn the extra fuel.

Done, after a few thousand dollars.

Yeah don't worry I will be getting a pump rebuilt professionally - I am in the UK and I believe Dieselpumpuk is the UK supplier for the uprated pumps. I plan to keep the part electric pump rather than going mechanical.

How do the elements work then? I know that there is a camshaft below which gets turned by the engine at half speed, this then pushes up on the rollers and plungers - guessing the elements are between the plunger and the delivery valves on top?

Exactly! The cam pushes on the elements and the fuel is sent to the injector. The element has a slot cut into it. The rack rotates the elements within the bore of the element. This rotation clocks the plunger's groove so that the element fills with a lot of fuel, or not much at all. The groove is where the fuel fills the element. :) I'll see if I can find a video I remember watching that animates this. :)

Diesel injection pump elements are super precision ground parts. Machining is not accurate enough, they must be precision ground and are of super tight tolerance to the plunger barrels which are ground to the same quality and are made of very hard steel.

Ah I see, so the rack will rotate the elements which sit inside the delivery valves, would the 6mm size come from the size of the slot for filling or is that the size of the output of the element through the delivery valve?

I can see why these would need to be strong as they must be acting like valves within the delivery valves?

true true!

some guys even tried with DV machining but afterwards had some
idle issues....

.

Imagine the pump elements as little pistons running up and down inside cylinders - because they are... :) They have bore and stroke just like the engine's pistons.

The number you see relating to elements is effectively the bore size. You can estimate element output by doing a simple area calculation.

6mm elements have 28.27 mm3 of area 7.5mm elements have 44.17 mm3 for a potential increase of about 150%.

Awesome, thanks for that, I did manage to find an animation of how the inline pumps work with the slot being where the fuel can bleed off, the less bleed off there is (eg the more its rotated) the more fuel is injected.