Well I figured I have given people enough of a rest from my somewhat bizzare threads or threads I get really involved with..Plus my desire to participate in makeing the black boxes of the limited systems on these engines more understandable to part time self servicing users like myself and others..

So I think perhaps it is worth examining and exploring the posibility of external testing of the delivery valves on the older 617 and 616 engines injection pumps.

My premise is to take a surplus injector line and do a leak down test with air. This on any suspect delivery valve. The valves will not visually check well enough and why disturb them unless the need to do so is proven?

Or to eliminate them as the possible contributor to any problem that may be related. Fortunatly flow errosion of the seats and valves has not seemed to be a major item but dirt and gunk can be an issue in my opinion.

Since a valve with little leakage will have to be compared against others I feel a plastic tube in the air line hooked to the air supply in a sizable loop. The other end of course connected to the injector line in a leakproof fashion might do well enough. Providing there is some fuel in the loop that the air will displace if there is any flow of air.

Of course the initial rush of air into the line should be metered slowly to the finish testing pressure to allow the fuel to remain in the loop as the air is compressed against the valve itself.

Once stability of the air supply is established the small amount of fuel should remain in a quiecent state in the bottom of the loop I believe unless there is valve leakage. I assume air bubbles will transit through the fuel at low leakage rates. Serious leakages will be more dramatic I suspect..

I just basically see it as another test if a cylinder or engine is not running quite right. We have never discused a good simple test for this area. Yet I sense with several posts in the last while the need is developing.

First if I agree with using wvo or not is not one of the issues. Still many wvo users have changed their injection pumps assuming the elements are trashed. In reality many may just have gummed up delivery valves on reflection.

Unfortunatly some elements on wvo will still be be trashed. Some members also felt that an injection pump that would work with wvo but refused to on diesel fuel. Always meant the elements where able to function with the heavier viscosity of the wvo. I am guilty of this feeling as well I supose.There is a possibility the valves would also have less leakage with the much heavier viscosity WVO enabiling pop pressure of the injectors to be reached. Those valves may have just been less able to seal well enough on the thinner viscosity diesel fuel as well.

So before the pumps are changed out perhaps it is more effective to do the test. If the need to clean them is positivly indicated so be it. Visual examination alone of a valve assembly that size may easily miss something I think.

Now I am far more curious about how very old injection pumps delivery valves that have always run on diesel fuel will be found condition wise. It is easily understandable unless they all seal in approximatly the same consistant fashion there will be unbalanced injection to some degree.

We all realise to test properly the enterance port to the element involved during testing will have to be open. So we will have to calculate where to position the crank for each delivery valve test spanning two revolutions of the crankshaft. I suspect a good fit between the lapped element piston and it's cylinder makes this mandatory at this point.

For quite some time I felt the principal reason our injection pumps go out of calibration over time was wear. The wear should in my opinion be simular from element to element. If so we would still have a good smooth idle. Now I am starting to doubt my earlier thoughts.

It could just as easily be grunge developing. This approach I would save for engines that do not sound quite right at idle.Providing the injectors have been checked and fuel pressure in the base of the injection pump is found to be where it should be first. Does anyone think this is a valid area for discussion? I am not sure the test will work even. Although it is better than no test at all and has a better than fair chance of working I think.

Also what do you think is the best approach to having the individual elements loading port open that is under test. A degree wheel or crude cardboard degree wheel temporarily mounted to the crank snout on the 617.? We might get by with simple extrapolation for the 616 as there are only two ports open on each crank cycle instead of the two and one half on the 617.

I would like to see people post what they think and variations of this approach. This has worked pretty well in the past in my opinion. I stilll feel that even if any approach does not come into general use the gains in understanding are still a major upside for all of us. We all can repair or easier understand what we are working on as a direct result of these types of threads and ensuing posts. Even the questions they bring forth lead to other things with time. Sometimes instantly. A lot of questions and sugggestions they bring forward are learning experiences for the common good as well.