Injection Pump Tour

[ja17]

Additional information added 6-15-04

quote:Do you have any photos of the inside of the injection pump?

Hello,
Here are a couple of photos to start with. I've started a new thread since this is a very complex subject. This may take a little time to complete.

Download Attachment: injection pump 1.jpg
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Download Attachment: injection pump 2.jpg
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There are six inputs that will affect the quantity of fuel injected by the pump. These are factory settings, manual adjustments, engine rpms, engine water coolant temperature, barometric pressure and accelerator linkage position. In addition to these six items, there are some pumps which may have one or two electric solenoids which change fuel mixture when starting or stopping the engine. (more to come)

Joe Alexander
Blacklick, Ohio

[ja17]

Here is a couple of photos of the hidden "block side" of the injection pump.
Download Attachment: inection pump, block side.jpg
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The oil supply line enters the pump in different locations depending on whether your pump is the self-contained with dipstick "early" variety,  or the engine lubricated "late". The earlier pumps 230-SL and early 250-SL had the oil line entering higher on the pump to supply an "oil ring seal" around the plungers of the injection pump (a oil level dipstick was needed for these pumps). Later series pumps were supplied a larger volume of oil which circulated through the pump and drained back into the engine (dipstick no longer needed).

Download Attachment: injection pump, block side2.jpg
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The second photo, also of the block side of the pumps shows the amazing and intricate maze of levers, springs and rods which relay infinite amount of inputs from the warm up device and the barametric compensator. (more to come)

Joe Alexander
Blacklick, Ohio

[rwmastel]

quote:.... depending on weather your pump is the self-contained with dipstick "early" variety .... The earlier pumps for 230-SL and early 250-SL had the oil line entering higher on the pump to supply an "oil ring seal" around the plungers of the injection pump

Joe,
What's the need for an oil supply tube if the pump is an early "self-contained" type?  Does this simply supply oil pressure, or does oil circulate through this line and the injection pump?  I guess this raises the question of why the later style pump doesn't need to supply an "oil seal ring".  Is this a physical seal in the later style?

Thanks for the education!

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Ben]

And if these pumps have an oil supply line........where does the oil go ?

I mean if it keeps feeding surely it drains somewhere........so ....
ehmmm ........I'm confused ! !

Again !!

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Naj ✝︎]

The oil line on the 230sl is for lubricating the delivery valves because this fuel has no lubricating properties that diesel has.
The oil dissolves with the fuel......and out the exhaust.
Thats the tale I've heard
naj

'Kloines Scheisserle'
65 230SL
68 280SL

[ja17]

Hello All,
These injection pumps are such a marvel. A true testimonial to fine German Engineering.It amazes me to behold everytime! The clearences between the injection plunger (piston) and the cylinder are in millionths of an inch!! We will get into this more later.

Consider that the early W113 injection pumps are a direct decendant from the earlier 300-SL injection pumps. I noticed that many of the 230-SL major pump castings were still the same or very similar. These 300-SL injection  pumps had a self contained oil supply also. 300-SL pumps were not installed into the block but were mounted on the outside and driven by an external driveshft instead of the internal splined coupling as in the 113. They had a dipstick and oil feed tube from the engine as did the early W113 cars.  Rod, Ben and Cees this brings up the question "where does excessive oil go and what is the oil feed line for?"

The 300-SL injection pump is externally mounted and driven by a external driveshaft so there is no way for the oil to drain back into the block! The same is true with the early W113 cars. There is no oil return. Naj, I believe you are on the right track.

The 300-SL workshop manual goes into an extensive description on operation and theory of this type of injection.
Consider the very close tolerences between the injection plunger (piston) and its cylinder, (millionths). Inside the cylinder is a tiny groove ringing its circumference. The metal oil tube in question supplies this groove with oil under pressure from the engine. This is a near perfect seal! The clearences are so tight it must nearly cut the oil molecules in half! (exageration).

Anyway it does a very good job sealing the plunger and which keeps the fuel out of the bottom end of the pump and enables the fuel to be pressurized and metered for injection. So in reality there is no seal as we know it, just an "oil seal". Naturally as things wear or oil becomes dirty or contaminated, the "oil seal" becomes less effective and some fuel or oil may wash by the seal and cause the level in the pump to rise! The engine oil pressure at idle should exceed the fuel pressure at idle or the overpowering fuel pressure will also bridge the "oil seal".

The later W113 injection (late 250-SL? and all 280-SL) had a fuel injection pump which was supplied with circulation of oil from the engine which constantly supplies oil closer to the bottom of the pump to be used in the "oil seals" and the lower end of the injection pump. Excessive oil simply drains back into the engine chain gallery via a newly drilled oil return hole in the engine end of the injection pump. Photos to follow soon!

Joe Alexander
Blacklick, Ohio

[ja17]

Here is a photo comparison of one "engine lubricated" and one "isolated oil supply" (dipstick needed) injection pump. The top pump would be from the later version M130 engines (280-SL), the lower pump might be from a late 230-SL or 250-SL. The earlier pumps (not shown) all had "isolated" (dip stick) oil supplies also.
Download Attachment: pump lubrication.jpg
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Joe Alexander
Blacklick, Ohio

[ja17]

Hello All,
The "drive end" of the injection pump is where the timing marks are located. The injection pump "rack"  can also be accessed from this side also. The rack must be free to move or the engine will not run. Engines subjected to long inactive storage or bad fuel may experience a "stuck" rack. In actuality, the precision pump plungers get jambed from rust or varnish and cause the rack not to move. See the photos. Feel free to question, comment or add information.


Download Attachment: injection pump drive end information.JPG
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Download Attachment: Injection pump timing marks 2.JPG
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Joe Alexander
Blacklick, Ohio

[ja17]

Here is some additional information on the left side of the injection pump.

Download Attachment: injection left illus. 3.JPG
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Joe Alexander
Blacklick, Ohio

[ja17]

Please excuse the repitition. I have added this information to this string so the data can be kept together. This is additional injection pump information dealing with rear adjustments and internals.

Do not engage the scew with the engine running!
"Engaging the screw when the engine is running will wind it all the way in. The screw or the adjuster can be damaged.
The screw is standard right hand thread. Turn it counterclockwise to move it out (leaner mixture) or clockwise, moving it inward (richening the mixture).

Download Attachment: gov. low range adjuster screw.JPG
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[View the screw removed. Notice that the six sided slotted screw is wedged between small leaf springs. The tension from these springs gives the screw the "click" feeling. As the screw is adjusted outward it may eventually move off the springs. At that point the "click " feeling is lost and The screw is free to move on it's own!


Download Attachment: rear pump cover off.JPG
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I am sure the factory sets up the pump with the screw set down deep enough in the leaf springs so that there is enough room to adjust up or down. Start somewhere in that range. The mixture of the engine will determine how much to adjust the screw after re-assembly as long as the adjustments do not take you past the limits.

Download Attachment: governor adjuster mechanism.JPG
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Download Attachment: governor adjuster mech. 2.JPG
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A snap ring holds the entire adjustment assembly in place. The three coil springs are acted upon by the adjustment screws. Each coil spring effects a different range of the centirfical governor.

The oil level on these "early" injection pumps should be checked periodically. It's oil supply is isolated from the engine oil. Oil should be added or drained accordingly. The level should be read after the dip stick is screwed all the way in. Later injection pumps had engine oil circulating through them and did not have to be checked.



Joe Alexander
Blacklick, Ohio