Which way Leans out your IP pump when you do the drip test--moving it towards the engine? Thats what I always thought.

I always thought perfect tuning of an IP was theoretically a nice ideal but as a practical matter there was a bit of luck, black magic and humor in doing so. Thats because with the pump loosened to do the Drip Test or Millivolt Test you sure could perfect results. But by the time you got all four bolts tight on the IP Pump, even the best mechanic would have probably shifted it a little bit out of whack. ( I wish they had stamped finely marked scales both on the IP PUmp and the side of the engine.)

I have done it maybe 8 or 9 times and lately what I do is just get a good drip test, and then on top of that after I get my best position, I would always nudge it a bit towards the engine as I tightened my Bolts. Then i would check my results again. I know i am going to get in trouble for saying this, but my engines always sounded the quietest after I barely got 1/8 th of a drip out of the spout, or barely nothing.

On my 240D and 300D moving the IP towards the block just increases the start of delivery timing during the drip test...So if I started at 20 degrees BTDC....then moving the IP towards the block can increase the degrees through 24 which is spec and all the way to the block it ends up at about 28 to 29 degrees BTDC...All the way away from the block was about 18 degrees BTDC....I think the lean or rich values are balanced in the pump when it is calibrated at the factory or injection shop...

You advance ignition by pushing the IP towards the engine and you retard ignition by moving it away.
I don't know if rich and lean apply to diesels unless maybe your talking about adjusting the rack or alda.

Personally I never felt the need to buy a drip tube. What your looking for is the point where fuel is not there then it is. Start of delivery is the region where fuel just begins to well up in the valve chamber.

Danny

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1984 300SD Turbo Diesel 150,000 miles

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So you are saying, outwards is Leaner? If I move it all the way outwards, then Start of Delivery would ultimately occur at 18 degrees BTDC. If I move it all the way inwards, Start of Delivery would be earlier, at 26 degrees BTDC?
I thought it was the other way around---For some reason, I thought that I observed moving the pump inwards made the flow from the drip nozzle less.

Anyway I was getting Bad Mileage and I had a noisey engine. The car the engine came from had an Odo reading 210K. Its a great engine generally. But I bought the Cluster also a year later and it was dead. I'm guessing the engine to be about 250K or more. I figured the chain had stretched.I'm changing the chain and I have pulled the pump and I am starting from 'scratch'.

Nothing sounds worse than a Badly tuned Diesel and nothing sounds better than a sweetly tuned Diesel. If worse comes to worse, there is a midrange where you are generally okay...and thats recovered by using a small dab of paint to mark where I started, which I always do. I sure wish they had scribed "Marks" on the pump and block!

I guess I am abusing the term and you are correct. All I am trying to say is that I like to make my drops practically nil or stop when I am adjusting my pump and they seem to do that by nudging it to the engine.

Since both of you agree ignition is advanced by nudging it towards the engine--I guess all I really said was I like it advanced a little.

You are correct...moving the pump towards the block makes the flow out of the drip tube stop earlier...This stop point is the begining of the injection...it stops because the plunger has shut off the fuel fill for that #1 injection pump chamber...the chamber has filled all it can and now the plunger is begining to pressurize and push the trapped fuel column towards the injector through the line.....It is odd to think of the fuel flow stopping for begining of injection but what we are actually seeing is the end of #1 injection pump chamber (fill) in preparation for the (push) of fuel to the engine injector...so stopping the drip is the piston or plunger top surface sealing off the fill and spill ports of the chamber so that it can push the fuel...it remains sealed off until the plunger returns back down after the full injection...the fuel is flowing through the IP from side to side (from filter through IP and out of IP back to the tank... and the little chambers are flooded until the plungers grab that little section of fuel and push it up...kind of like those rotating tables at some old time restaurants....you grab what you want to eat as it goes past....the same quantity of fuel is pushed regardless of when it begins to push...earlier or later...advanced or retarded....just like turning a distributor on a gasser makes the spark occur earlier or later...the size of the spark is the same .... This is how it was explained to me by my friend that owns a Bosch injection service and rebuilds these things for a living.....For throttle, the little plungers are all rotated together by the rack to determine how much fuel they pick up and push.....more fuel push...more rpm....less fuel push...less rpm.....I hope I am explaining this how I was told....

From what I gather the drip tube is so that you can see the cutoff point of the chamber without having to overcome the delivery valve spring tension as the delivery valve should be removed for this test....If left in place you are now adding delivery valve resistance to the small flow and this will skew your readings....This straight from the Bosch guy.....

i copied it and saved it.............