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.

What about doing this "leak down test with air' on an IP sitting on the work bench?

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

No problem I can think of other than you have to figure out a way to verify the individual delivery valve under test has the internal element port open.

This would always be the most difficult part on or off the engine during tests. Perhaps the pump sidecover would have to be removed to verify the delivery valve piston is at the minumin point on the cam or close to it. I feel the non intrusive locating of the piston in that element is better and easier than any removal of side covers etc.

An on the engine approach might involve removing the normal lines or line. Watching for the peak fuel rise in the fitting before installing your test line. Then rotate the crank a predetermined amount of degrees to gaurantee the internal elements piston has decended to the bottom of it's bore. Then air test.

I suspect that rotation to be exactly 360 degrees or exactly one crankshaft turn. You could mark with chalk the point were the elements discharge stops and turn the crank till the marks line up again should get you there I think.

Not absolutly sure till I think about it. Yet probably correct. In fact a pump on the bench would indicate the piston top position the same way. If the pump is fuel dry probably filling the fitting with oil until the piston rising up no longer displaces it. Then rotating the pump shaft exactly or close to 180 degrees will get you bottom centre for that elements piston.

This of course because the injection pump travels half the distance or speed the crankshaft pully does.

[QUOTE=barry123400;2489695]No problem I can think of other than you have to figure out a way to verify the individual delivery valve under test has the internal element port open.

Not sure I'm on the right track to understanding this...but if you blew air through #1 (as indicated by the IP mark), isn't that "port open"?, therefore (on a 616 for example) wouldn't the "next to fire' cylinder be 90 degrees away and be indicated by being open to blow air through the next delivery valve and out the return or visa versa as we did with #1?

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Yes I can be confusing. The port I reffer to is located very low on the cylinder barrell in the pumps element.

This is where fuel enters the element chamber above the piston. The piston has to be low in the cylinder or barrel to enable this. You need to have that fuel enterance open for the test air to escape if it is getting past the delivery valve.

Now for top dead centre or the piston at the top of it's stroke for any individual element. There is no provision by marks existing that occur to me. Remember we are specifically talking about a bench test here.

So for each element you establish it. It will occur when any fuel you place in the fitting the injector line screws into stops overflowing as you turn the injection pump shaft. You will continue to add fuel as required until the spilling over ceases or the level will not rise anymore. That will be top dead centre for that elements piston.

Then rotating the injection pump shaft 180 degrees or half a turn will put that piston at bottom in it's cylinder. So low the filling port is exposed. That is the path for any air that may escape past a leaky delivery valve.

I know I am not very clear but this is also all new to me as well. Just kind of off the cuff.

If i were to do this on a table with a pump. I would fabricate something to hold a degree wheel onto the injection pump shaft snugly. Yet still allow enough room to turn the shaft. Or just visually if you used a pointer type indicator. I think you have to use something.

On this I would mount even a cheap kids degree wheel disk from a surplus protractor kit. Set it to a zero position reference point on the pump. When you have found the top dead centre. Then rotate the pumps shaft till 180 degrees rotation is indicated. You would do this proceedure over again for each delivery valve that you wanted to test on the pump.

Clarity is important I agree. Whatever it takes for me to transfer my thoughts by the written word never hesitate to ask. I am well aware of my shortcomings in that way.

On request I will give it my best shot and other members will help too. This whole thing is a community thing with people with common interests.

Actually it is also one of those things that is probably easier to do than describe.

When I worked in a Fuel Injection Shop during the rebuild of Fuel Injection Pumps the Delivery Valves were inspected visually.
For small issues they were lapped in a similar fashion to lapping a Valve with 1600 grit grinding compound.
Other types of damage or wear called for replacing of the Delivery Valve.

With clean Diesel Fuel there is no much to cause Delivery Valves to stick or gunk up.
Water sitting in the Delivery Valve area overnight can sometimes cause them to stick as can old dried Diesel Fuel if the IP has sat and not been used for a long time.

Sometimes the Delivery Valve Spring fatigue and break and I have also seen them rusted through.

Anything gritty going through the Fuel Injection Pump is more likely to damage the Elements/Plungers and Barrels than the Delivery Valve and wear on the Elements causes eratic Fuel Delivery.

When an inline type Fuel Injection Pump is rebuilt they indeed use a degree (Motorcycle shops used to sell them) wheel on the end of the camshaft and each of the Elements is Drip/Flow Timed and Begin of Injecion is set for each Element.

Another area that causes erratic Fuel delivery is wear between the Injector Spray Nozzle wall and the Nozzle Pintel. This is another area like the Elements were grit will cause lengthwise score marks on the precision surfaces.
Wear in this area causes more Fuel to leak buy and go out of the Fuel Return Lines instead of being Injected into the Engine.

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84 300D, 82 Volvo 244Gl Diesel

I agree with your post needless to say. My concern has been slowly increasing because of the alternative fuel practice. Plus the seemingly not changing the fuel filters generally unless they choke off or perhaps a person sees a long trip ahead of them. Some dirt etc will migrate through that pretty well loaded filter and process through the pump. Especially when it is being pushed so hard through a restricted filter.

Since you are also a very observent member and well versed on site. I know my suggestions at this point in that area are not well considered. I feel stronger over time that some of my opinions have more weight to them than they had some time ago.

Funny how I still question the number one rod failure thing still but less and less as time moves. Now to me at least some evidence is surfacing. Really felt out on a limb with that one.

Basically in my opinion it is false economy in more ways than the majority think to have too much restriction in the fuel supply system to the base of the injection pump. So much so a person should really have a gauge to watch for when that pressure starts to decrease beyond a certain point. Then rectify it. The gauge is also a very useful addition for troubleshooting in the system that causes the most grief on these old diesel engines. It will in many cases provide an early warning system that there is a problem somewhere.

I think it has to be a given now that all these engines and the fuel injection pump function best at about 19 pounds base pressure. It also looks like the manufacturer is in general agreement.

What has all this to do with the delivery valves? Reciently there have been some reports of finding a lot of solid particles on the seats and valves on old pumps running only diesel fuel. I figure it has to be getting by the seldom changed secondary fuel filter. Logically if they are appearing on some cars they will be on others as well.

Then there are all the threads where the poster has done all the so called normal things and the problem is continuing. Especially the rough idle incidences.

At that point I can see little harm in testing the delivery valves for their sealing qualities. Using things like the milli volt system will locate the suspect injection pump element. It is still cheaper for us to spend some time instead of money to clear or condem things of having possible problems. As long as a test is cheap and possibly indicated for a suspect condition.

You want to systematically condem or clear portions of the various systems. Can we change a defective delivery seat that will not test properly ourselves? That is one that is not responding to cleaning? I know we can change the moving valve portion if defective ourselves.

Most these pumps are just so old now and getting older by the day. I personally like an engine that meets my expectations. My four mercedes diesels engines in general run as perfectly as the type can generally speaking. Just a matter of good coincidence and I can take no credit for this.

Too bad my two carb fueled gas mercedes cars are not simular. I have owned mercedes cars with perfect functioning zenith carbs but not at this point in time. Those carbs and systems need work.

If the Fuel Injection Pump is on the bench and you want to know the position of the Element Plunger you can simply remove the bottom Pan and view the Camshaft Lobe positions.

I understand that people do things just for the joy of investigating them as well as the results.

However, if a person believes their Delivery Valves are not seating well the could be pulled out inspected and carefully lapped.

The lapping is not hard; you just need to keep the lapping compound only in the seating area of the valve. You do the by dipping a Round Tooth pic into the lapping Compound (premixed to a paste) and get a tiny amount on the tip that you apply to the Valve seating area.

Put the Vlalve back into the lower Valve Body and rotate it back and forth by hand.
When your done clean it and look at the seating areas through something that has some magnification like a Loup and see if the Lapping cleaned up the Valve seat.
If it did your are in business and you can put it back into the IP. Otherwise you need to decide if you need a new Delivery Valve.

I cannot say if installing a new Delivery Valve will change the delivered Fuel Quantity or not.

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84 300D, 82 Volvo 244Gl Diesel

Again I personally like diesel 911s method as a valid approach to finding bottom dead centre of the elements.Experience rules.

The effect on fuel delivery will depend on the amount of leakage I suspect.

The leakage is critical to sealing the pressure in the injector line when the element piston is decending. If for example enough fuel backflows. After the element takes on a new charge of fuel. It will have to spend some of the fuel volume making up what drained back out of the injector line first or the lost pressure before making enough pressure to open the injector. So that injector will be late.

As the average inactive or waiting pressure in the line will be much less than the other injector lines with better delivery valve sealing. This is a smattering of thought not proven but suspect and has to allow for a very small compressability factor of the fluid. Normally not an issue but the quantities we are dealing with on normal release are almost miniscule.

For all practical purposed fliuids do not change volume when they are compressed.. In this function the slight amount if they really do could be an important factor in my opinion.

It could also instead be a function of different temperatures as we all have to agree heated fuel and fluids expand more than the same fuel at cooler temperatures. So the effect of the backflow through the delay valve may be some form of cooling tower.

Compressing fluid to these kind of pressures makes substantial heat. Recompressing seems to have some effect. Just a lot of guessing here but the real effect whatever it is seems to be there.

If it was not an issue the pump manufacturer would not have incorporated the check or delivery valves in the pump.

It may also be something as simple as the backflow of fluid that occurs at a rapid pace may be displacing the ability of the element to refuel properly. Even under normal operation there are some horrible pressure spikes in the pump in the refueling area of the elements.


If a seriouisly leaking delivery valve is present That injector will be really late timing wise if able to fire fuel out at all. These are just my thoughts and speculations. Enough variences between the sealing qualty of the delivery valves to me will be noticable with the engine running. I think all the injectors might still spray just not in the right timing sequence and volume. The leakier the individual delivery valve the greater the timing delay. If leaky enough that injector might not spray at all. I guess we could speculate all day on what is really occuring with a poorly sealing relief valve.

There is even the race for the delivery valve to close perhaps before certain instantainious pressure waves coming back down the injector line can enter the element. They could be considered a dynamic element beyond my limited grasp. We I believe will just have to deal with observed effects rather than fluid dynamics. There could even be some correlation between the injector return or relief valve and the delivery valve. Who knows?