Hey guys-

I'm checking the timing on my injection pump, doing it solo...so I've been rotating the motor and looking at what's going on at different points in the cycle. I rotate the motor to a point, then pump the hand pump and observe the drip tube:

1. At about 35-40deg BTDC, I get a stream of fuel flowing from the drip tube for cylinder #1.
2. At 24deg BTDC, the flow abruptly stops/slows to a trickle/drip.
3. At about 15 deg BTDC I have no fuel flow from #1.

There's definitely a transition point at 24deg BTDC but it appears that it's the stop of fuel delivery, not the start. Am I doing something wrong, or am I messed up on nomenclature? The motor seems to be running pretty well...it's my first diesel so I don't have a means for comparison, but I can drive it just fine on the highway. I'm getting about 20-21mpg.

What is the length of fuel delivery; ie how many degrees between the start and stop of the delivery sequence for each cylinder?

Thanks-
Rob

79 300SD W116 OM617.950

The drip timing method uses a special tube that is used in place of the #1 injection line.

Set the engine to 24*BTDC on #1's compression stroke.
Remove the injection lines,
Remove the #1 delivery valve top (The thing the injection line attaches to).
Remove the delivery valve and spring but leave the valve body in.
Put the delivery valve top back on and attach the tool like you would an injection line.
Remove the vacuum line from the shut-off valve.
Fix the accelerator to full throttle. (DO NOT FORGET IT WHEN YOU GO TO START THE ENGINE)
Pump primer until all the bubbles are gone from the clear fuel lines and a constant stream comes out the tool.
Loosen all 4 pump mount bolts (Don't forget the one at the back of the pump).
Turn the IP until the fuel is coming out the tool 1 drip per second.
Put everything back together, tighten all bolts, bleed the system, start the engine, and check for fuel and oil leaks.

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Don't worry about how long it injects, degrees between the start and stop of the delivery, etc. Just set the timing and go with it.

Attached Thumbnails

 

Thanks Forced.

After I sampled the flow at different points I did what you suggest.

Set it to 24BTDC, removed lines, wired throttle, removed vacuum lines, removed valve and spring from #1 and attached the drip tube, loosened the IP nuts (there were only 3 on mine fwiw), marked current location of pump and tried fine-tuning it.

I rotated the pump to the end of its travel, so that the top of the pump was far away from the engine block, at this point I got a solid stream of fuel flowing through the drip tube.

I then gently pushed the top of the pump towards the engine until flow through the drip tube stopped abruptly. I think a drop came out a few seconds later. I locked the IP nuts down.

I checked the new setting against the line I had scribed as the original setting and it was very close, like a degree or so.

But...is my pump set up correctly or have I set the stop (not the start) of fuel delivery to the 24BTDC point? I've read other posts and the impression I get is that rotating the top of the pump towards the block causes an increase in flow through the tube...whereas when I rotated the top towards the engine block I was getting flow to decrease/stop.

Thanks-
Rob

Hello...You have come to the right place...There is a ton of info on IP timing on this forum.....
If this is your first try ...you have it right on very close from what you said......
The confusion with this drip tube (stopping the flow) at 24 BTDC is the fact of the plunger moving up the barrel in The #1 IP element has just almost sealed off the fuel fill port so that the fuel pressure (push) can begin....Similar to how a 2-stroke engine with cylinder ports operates.....The piston covers the ports on the way up the cylinder so compression can occur...In a nutshell..End of barrel fuel fill is the same as begining of pressurization or (delivery)....the fuel spills in on top of the little piston or plunger as it is on its way up...as the port gets covered up by the piston no more fuel is going in the barrel....
There is all kind of debate about counting drops right at the threshold of almost complete fill port closure...but the variable is the hand pumping pressure....There is info on setting up a fuel can a few feet above the IP to supply a constant fuel pressure instead of pumping....I am going to do that next time but I could not discern any performance difference slightly above or below the 24 degree mark.....but I like to do it correct if I can...
I took the IP from full advance stop to full retard stop and the engine still cranked and ran...but it is always good to do it like the factory manual says....
You can search under my username with the term (IP) or search under another member (leathermang) the same way ...He is really up to snuff on the IP timing.....
But from your post sounds like you got it close...just the normal confusion about fuel stopping being delivery starting....It took me pulling out most of my remaining hair to understand over several months....Of course I am a slow learner but I can grind it down eventually.....If I am gonna be stupid ...I gotta be tough......hope this helps ...getting late......I am sure you will get some more good advice from the group here... good folks!......IP timing questions on this forum is like chumming for sharks...Cheers!...kevin

__________________
1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

Almost forgot ...Your question of how many degrees does delivery cover....
That is how more or less fuel gets to the injectors....
IP cutoff....no degrees
Idle...very few degrees
Full throttle....a few more degrees..I could find them but too lazy now....
It is amazing how little difference in the fuel quantity between idle and full load....
Here are the measurements of an IP plunger for my 1980 240D...Close to within a couple of thousanths of an inch...not dead on but gives you an idea of the approximate volumes pushed between the two limits if you want to calculate ...

Plunger Diameter.... .216"
Plunger Idle Effective stroke.... .180" including idle notch...
Plunger Full Load Effective stroke..... .260"
The above figures are what I measured physically...Bosch numbers are probably more or less...

At low speed the plunger releases the pressure earlier through a helix groove machined into it...
At full load the plunger releases the pressure later along the same groove...
The plungers are rotated a few degrees by the control rack to make this happen....
This is hard to explain but easy to understand if you can see the parts...If I knew how to put pictures on here I could attach a couple so you could see...

Like a modified bicycle hand tire pump....
There is a full stroke every time...but at (IDLE) the pump would only pressurize the first couple of inches as the piston travels down....... after that a port would open in the piston for the remaining amount of stroke allowing the air in the tube to escape out the top into the air rather than be pushed into the tire....

At (Full Load)....The piston travels almost all the way down the tube pushing all the air into the tire until the last inch when the little port would open on the piston releasing the very small amount of pressure left back into the air...

Half speed would be in between these points.....

Getting way too late now I am starting to ramble....you probably got it figured out anyway....Good job..!

__________________
1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

In other words...

The injection duration and start of delivery is fixed, only the amount of fuel injected changes.

There are 4 bolts. One is at the lower back of the pump by the lower end of the oil filter housing.

Ah, ok...now it makes more sense.

So when I'm looking at fuel coming through the drip tube, I'm not observing fuel delivery occurring...instead I'm observing filling of the barrel. Delivery begins at the completion of barrel filling. So by setting the completion of barrel filling to the 24 BTDC then I know that delivery will start immediately afterwards; ie exactly at 24 BTDC.

Re: fuel cell...I remember seeing yours and leathermang's posts on it and I think that's a great idea. It was tricky to manage pumping the hand pump at the same time as rotating the IP. I've got a fuel cell that I've been using to sync the carbs on my motorcycle, will use that next time. I take it I connect the line from the cell to the inline filter, as if it were coming from the tank?

I'll look for the 4th bolt, maybe it's loose or something. The three I found were on the flange at the front of the IP. Two on the top that are visible and accessible from the top; and one that is tucked below that I accessed from the bottom, coming up in front of the front wheel and in the vicinity of the front of the steering gearbox. I see a hexbolt on the far back of the IP in the vicinity of the vacuum lines, but it looked different from the others and I didn't want to touch it. I tried searching online for photos of the locations but didn't find anything; if anyone's got any shots of the 4th bolt please post

Thanks-
Rob

Yep...That is what is happening ...The fuel flow out of the drip tube is the indication that the little plunger (piston) is coming up the barrel as you are hand turning the IP through the timing chain system and has not yet blocked the fill port in the barrel...So the fuel is leaving the barrel via the drip tube...
The fuel flows from the drip tube because it has to go somewhere with the small amount of pressure applied by the hand pump or other source...Fuel is also trying to get through the IP return back to the filter manifold but the drip tube has far less resistance to flow so that is where it goes... The one drop per second rate @ 24 BTDC is the very threshold of complete fill port closure by the piston...
That is why the delivery valve and spring must be removed first...It would be too hard to unseat the valve because of the spring pressure when hand turning the IP...You could not determine the exact point because of added restrictions...Some people try to do what is called a (well-up test)....A peculiar little set up with the only difference being is that they are trying to watch for the seepage of fuel around the valve as the piston pushes the first quantity of fuel out the valve...I do not know why this test is popular other than they are trying to get around putting on a drip tube.. I have done it and it is close to the drip method if the delivery valve is free and you like to use paper towels and magnifying glasses to set the IP....Bosch does not recommend this test as another variable(delivery valve) is added to the mix...I am still waiting for a good reason to do the well-up instead of the drip test...maybe just because no drip tube was available at the time...
There are a couple of other timing methods that involve more equipment than the drip tube...I would like to get the electronic pickup type one day just to play with and compare...All of the above info was told to me by a Certified Bosch IP shop owner with 20 or so years of experience....So far he has been able to answer all of my silly annoying questions with a good measure of grace and kindness.....I may be getting close to bothersome...so I have to space them out over time now and bring offerings of coffee and such...

__________________
1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

Thanks for explaining this Kevin. I was lurking thinking that Rob had it all wrong and how could his car even run that way Now it makes sense.

__________________
'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

PatBob.....

Yes I must say Rob did "Most Excellent" on his first go at it...It took me days to figure it out just a little bit...I did not know this forum existed back then...It sure would have helped this old toad....
I must confess that I also am one of the IP (Lurkers)...or maybe a..................... (Timing Tom)........

__________________
1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

Most excellent...heh more like beginner's luck. Don't jinx it! I haven't yet gotten everything back together and started her up.

I was also thinking along the lines of patbob...the car starts pretty well as it is...I'd think that performance would be way down if the IP were that far off the mark.

As for the fuel economy, I'm replacing glow plugs and leaning out the ALDA a little in hopes that it helps. We will see

Thanks all-
Rob

Understanding the IP timing process is easy. Just come to logical, common sense conclusions. Then reverse those conclusions 180 degrees!!!

I'd love to interject a more detailed list of steps of the method my " Indy " friend showed me but I don't have time just now. I have nicknamed it the " Spit at ya " timing check test for these in-line Bosch
IP(s). Basically you only take the bottom fuel line connection [I suppose you could take loose the top]. There is no need to disassemble anything more or to pump fuel in any way.

You start by opening the oil filler cap so you can see when the engine is on the compression stroke for #1... this by seeing the #1 cam lobes approaching the up [on top ] position. Take the #1 fuel line loose. By taking the bottom loose, I think you are more likely to see the fuel spit out when the IP unloads into the fuel line. You watch the crank timing marks as soon as you see it dropping below 30-40 degrees and then when it does spit out fuel, this is essentially where the IP's timing is set when you look at the timing mark. If it is 24 Deg. + or - 1 to 2 degrees, I for one feel that this is all you need. If off by more than 2 degrees, yes you tip the top of the IP toward the engine to advance the timing and the reverse to retard the timing.

Just funning ya Kevin,

Got everything back together, seems to start and run fine. Thanks again for the help on this.

Rob

Great! Did you set it to 24*BTDC after all or did you advance it to 26?